9.50.04 - Segger Microcontroller - Datasheet.Directory

emUSB-Device

USB Device stack

User Guide & Reference Manual

Document: UM09001

Software Version: 3.12

Revision: 0

Date: May 4, 2018

A product of SEGGER Microcontroller GmbH

www.segger.com

Disclaimer

Specifications written in this document are believed to be accurate, but are not guaranteed to

be entirely free of error. The information in this manual is subject to change for functional or

performance improvements without notice. Please make sure your manual is the latest edition.

While the information herein is assumed to be accurate, SEGGER Microcontroller GmbH (SEG-

GER) assumes no responsibility for any errors or omissions. SEGGER makes and you receive no

warranties or conditions, express, implied, statutory or in any communication with you. SEGGER

specifically disclaims any implied warranty of merchantability or fitness for a particular purpose.

You may not extract portions of this manual or modify the PDF file in any way without the prior

written permission of SEGGER. The software described in this document is furnished under a

license and may only be used or copied in accordance with the terms of such a license.

Trademarks

Names mentioned in this manual may be trademarks of their respective companies.

Brand and product names are trademarks or registered trademarks of their respective holders.

Contact address

SEGGER Microcontroller GmbH

In den Weiden 11

D-40721 Hilden

Germany

Tel. +49 2103-2878-0

Fax. +49 2103-2878-28

E-mail: support@segger.com

Internet: www.segger.com

Manual versions

This manual describes the current software version. If you find an error in the manual or a

problem in the software, please inform us and we will try to assist you as soon as possible.

As of version 3.00 the history has been reset. Older history entries can be found in older versions

of this document.

Print date: May 4, 2018

Software Revision Date By Description

3.12 0 180504 RH

USB Core:

• Added function USBD_RemoveOnEvent().

• Removed functions USBD_SetLogFunc() and USBD_SetWarnFunc().

Audio class:

• Added function USBD_AUDIO_Read_Task().

• Added function USBD_AUDIO_Write_Task().

3.10 0 180322 RH

BULK class:

• Added function USBD_BULK_Add_Ex().

Update to latest software version.

Added Audio chapter.

3.08 0 180212 RH

USB Core:

• Added function USBD_RegisterSCHook().

• Added function USBD_AddEPEx().

3.06e 0 180112 RH Update to latest software version.

3.06d 0 171219 YR Update to latest software version.

3.06c 0 171204 RH USB Core:

• Added I/O functions.

3.06b 0 171013 YR Update to latest software version.

Corrected USBD_WriteEP0FromISR name (was USB__WriteEP0FromISR).

3.06 0 170915 RH

Printer class:

• Added function USB_PRINTER_ConfigIRQProcessing().

• Added function USB_PRINTER_TaskEx().

USB Core:

• Added USBD_SetCacheConfig().

Chapter “Getting started” revised.

3.04 0 170724 YR Update to latest software version.

Added chapter “emUSB-Device-IP”

3.02q 0 170717 YR Update to latest software version.

3.02p 0 170714 RH Update to latest software version.

3.02o 1 170710 YR

Chapter Combining USB components:

• Added information on the MSD+MTP combination feature.

Added Chapter “Profiling with SystemView”.

3.02o 0 170701 RH Major revision of the manual.

• Manual converted to text processor emDoc.

3.02n 0 170612 SR Update to latest software version.

3.02m 0 170608 RH Update to latest software version.

3.02l 0 170602 SR Update to latest software version.

3.02k 0 170410 RH Function USBD_AddEP(): Parameter ’Interval’ changed.

3.02j 0 170301 RH Update to latest software version.

3.02i 0 170126 SR Update to latest software version.

3.02h 0 170126 SR Update to latest software version.

3.02g 0 170123 SR Update to latest software version.

3.02f 0 170104 RH Update to latest software version.

3.02e 0 161215 RH Update to latest software version.

3.02d 0 161118 RH Update to latest software version.

3.02c 0 161103 RH Update to latest software version.

Software Revision Date By Description

3.02b 0 161028 RH Chapter SmartMSD:

• Renamed functions according to the emUSB V3 conventions.

3.02a 10 161018 RH Update to latest software version.

3.02 9 161007 SR

Chapter CDC:

• Updated Overview - Added Windows 10 Support.

• Updated Installing the driver. Section verification combined with In-

stalling driver.

• Updated section The .inf file

• Added new section: Signing the package

• Testing communication to the USB device updated.

3.02 8 160930 RH

Chapter CDC Data structures:

• Removed CTS from USB_CDC_SERIAL_STATE.

Chapter BULK communication:

• Removed description of the Segger USB driver(not necessary any

more)

• BULK host API and sample applications support for Linux and MacOSX

added.

• Added new function USBD_BULK_SetMSDescInfo().

• Added new function USBBULK_GetDevInfoByIdx().

• Removed description of deprecated host API functions.

Chapter SmartMSD:

• Added memory usage calculation.

Many minor corrections.

3.00g 7 160822 RH

Update to latest software version.

Chapter Target OS Interface:

• New advanced OS layer interface.

Chapter Mass Storage Device Class (MSD):

• Added new function USBD_MSD_RequestRefresh()

3.00f 6 160720 YR

Update to latest software version.

Chapter SmartMSD:

• Changed function prefix to SMSD.

• Removed obsolete functions.

3.00e 5 160708 RH Update to latest software version.

3.00d 4 160608 YR Update to latest software version.

3.00c 3 160523 YR

Update to latest software version.

Chapter Bulk communication:

• Added paragraph “Writing your own host driver”.

3.00b 2 160427 YR Update to latest software version.

3.00a 1 160415 SR

Chapter USB Core functions:

• Updated prototype for USBD_SetMaxPower.

Chapter HID:

• Added new function for Setting a callback for SET_REPORT.

Chapter Debugging:

• Changed all prototypes from USB_* to USBD_*.

3.00 0 160212 YR Initial Version

About this document

Assumptions

This document assumes that you already have a solid knowledge of the following:

• The software tools used for building your application (assembler, linker, C compiler).

• The C programming language.

• The target processor.

• DOS command line.

If you feel that your knowledge of C is not sufficient, we recommend The C Programming Lan-

guage by Kernighan and Richie (ISBN 0--13--1103628), which describes the standard in C pro-

gramming and, in newer editions, also covers the ANSI C standard.

How to use this manual

This manual explains all the functions and macros that the product offers. It assumes you have

a working knowledge of the C language. Knowledge of assembly programming is not required.

Typographic conventions for syntax

This manual uses the following typographic conventions:

Style Used for

Body Body text.

Keyword Text that you enter at the command prompt or that appears on

the display (that is system functions, file- or pathnames).

Parameter Parameters in API functions.

Sample Sample code in program examples.

Sample comment Comments in program examples.

Reference Reference to chapters, sections, tables and figures or other doc-

uments.

GUIElement Buttons, dialog boxes, menu names, menu commands.

Emphasis Very important sections.

Table of contents

1 Introduction ..................................................................................................................19

1.1 Overview .....................................................................................................19

1.2 emUSB-Device features ................................................................................ 20

1.3 emUSB-Device components ........................................................................... 21

1.3.1 emUSB-Device-Bulk ...........................................................................21

1.3.2 emUSB-Device-MSD .......................................................................... 21

1.3.2.1 Purpose of emUSB-Device-MSD ................................................21

1.3.2.2 Typical applications .................................................................22

1.3.2.3 emUSB-Device-MSD features ................................................... 22

1.3.2.4 How does it work? ................................................................. 22

1.3.3 emUSB-Device IP-over-USB ................................................................23

1.3.3.1 Typical applications .................................................................23

1.3.4 emUSB-Device-SmartMSD .................................................................. 23

1.3.4.1 Typical applications .................................................................23

1.3.5 emUSB-Device-CDC ........................................................................... 23

1.3.5.1 Typical applications .................................................................23

1.3.6 emUSB-Device-HID ........................................................................... 23

1.3.6.1 Typical applications .................................................................23

1.3.7 emUSB-Device-MTP ........................................................................... 24

1.3.7.1 Typical applications .................................................................24

1.3.8 emUSB-Device-Printer ........................................................................24

1.3.8.1 Typical applications .................................................................24

1.3.9 emUSB-Device-RNDIS ........................................................................24

1.3.9.1 Typical applications .................................................................24

1.3.10 emUSB-Device-CDC-ECM .................................................................. 25

1.3.10.1 Typical applications ............................................................... 25

1.4 Requirements .............................................................................................. 26

1.4.1 Target system ...................................................................................26

1.4.2 Development environment (compiler) .................................................. 26

1.5 File structure ............................................................................................... 27

2 Background information ..............................................................................................28

2.1 USB ............................................................................................................29

2.1.1 Short Overview .................................................................................29

2.1.2 Important USB Standard Versions ....................................................... 29

2.1.3 USB System Architecture ................................................................... 30

2.1.4 Transfer Types .................................................................................. 32

2.1.5 Setup phase / Enumeration ................................................................ 32

2.1.6 Product / Vendor IDs ......................................................................... 32

2.2 Predefined device classes ..............................................................................33

2.3 USB hardware analyzers ............................................................................... 34

2.4 References .................................................................................................. 35

3 Getting started ............................................................................................................ 36

3.1 How to setup your target system ...................................................................37

3.1.1 Take a running project .......................................................................37

3.1.2 Add emUSB-Device files .....................................................................37

3.1.3 Configuring debugging output .............................................................37

3.1.4 Add hardware dependent configuration ................................................ 38

3.1.5 Prepare and run the application .......................................................... 38

3.2 Updating emUSB-Device ............................................................................... 40

3.3 emUSB-Device Configuration ......................................................................... 41

3.3.1 General emUSB-Device configuration ................................................... 42

3.3.1.1 USB_DEVICE_INFO .................................................................42

3.3.2 Additional required configuration functions for emUSB-MSD .................... 42

3.3.3 Descriptors ....................................................................................... 43

4 USB Core ....................................................................................................................44

4.1 Overview .....................................................................................................45

4.2 Target API ...................................................................................................46

4.2.1 USB basic functions ...........................................................................48

4.2.1.1 USBD_GetState() ................................................................... 48

4.2.1.2 USBD_Init() ...........................................................................49

4.2.1.3 USBD_IsConfigured() ..............................................................50

4.2.1.4 USBD_Start() ........................................................................ 51

4.2.1.5 USBD_Stop() ......................................................................... 52

4.2.1.6 USBD_DeInit() ....................................................................... 53

4.2.2 USB configuration functions ................................................................54

4.2.2.1 USBD_AddDriver() ..................................................................54

4.2.2.2 USBD_SetISRMgmFuncs() ....................................................... 55

4.2.2.3 USBD_SetAttachFunc() ........................................................... 56

4.2.2.4 USBD_AddEP() .......................................................................57

4.2.2.5 USBD_AddEPEx() ................................................................... 58

4.2.2.6 USBD_SetDeviceInfo() ............................................................ 59

4.2.2.7 USBD_SetClassRequestHook() ..................................................60

4.2.2.8 USBD_SetVendorRequestHook() ............................................... 61

4.2.2.9 USBD_SetIsSelfPowered() ....................................................... 62

4.2.2.10 USBD_SetMaxPower() ........................................................... 63

4.2.2.11 USBD_SetOnEvent() ............................................................. 64

4.2.2.12 USBD_RemoveOnEvent() ....................................................... 66

4.2.2.13 USBD_SetOnRxEP0() ............................................................ 67

4.2.2.14 USBD_SetOnSetupHook() ...................................................... 68

4.2.2.15 USBD_WriteEP0FromISR() ..................................................... 69

4.2.2.16 USBD_EnableIAD() ............................................................... 70

4.2.2.17 USBD_SetCacheConfig() ........................................................ 71

4.2.2.18 USBD_RegisterSCHook() ........................................................72

4.2.3 USB I/O functions ............................................................................. 73

4.2.3.1 USBD_Read() .........................................................................73

4.2.3.2 USBD_ReadOverlapped() .........................................................74

4.2.3.3 USBD_Receive() .....................................................................75

4.2.3.4 USBD_Write() ........................................................................ 76

4.2.3.5 USBD_CancelIO() ................................................................... 77

4.2.3.6 USBD_WaitForEndOfTransfer() ..................................................78

4.2.3.7 USBD_WaitForTXReady() ......................................................... 79

4.2.3.8 USBD_GetNumBytesInBuffer() ................................................. 80

4.2.3.9 USBD_GetNumBytesRemToRead() ............................................ 81

4.2.3.10 USBD_GetNumBytesRemToWrite() .......................................... 82

4.2.3.11 USBD_StallEP() .................................................................... 83

4.2.4 USB Remote wakeup functions ............................................................84

4.2.4.1 USBD_SetAllowRemoteWakeUp() .............................................. 85

4.2.5 Data structures .................................................................................86

4.2.5.1 USB_ADD_EP_INFO ................................................................ 86

4.2.5.2 SEGGER_CACHE_CONFIG ........................................................ 87

5 Bulk communication ....................................................................................................88

5.1 Generic bulk stack ....................................................................................... 89

5.2 Requirements for the Host (PC) ..................................................................... 90

5.2.1 Windows .......................................................................................... 90

5.2.2 Linux ............................................................................................... 90

5.2.3 macOS .............................................................................................90

5.3 Example application ......................................................................................91

5.3.1 Running the example applications ....................................................... 92

5.3.2 Compiling the PC example application ..................................................93

5.3.2.1 Windows ............................................................................... 93

5.3.2.2 Linux .................................................................................... 93

5.3.2.3 macOS ..................................................................................93

5.4 Target API ...................................................................................................94

5.4.1 Target interface function list ............................................................... 94

5.4.2 USB-Bulk functions ............................................................................96

5.4.2.1 USBD_BULK_Add() ................................................................. 96

5.4.2.2 USBD_BULK_Add_Ex() ............................................................ 97

5.4.2.3 USBD_BULK_SetMSDescInfo() ................................................. 98

5.4.2.4 USBD_BULK_CancelRead() ...................................................... 99

5.4.2.5 USBD_BULK_CancelWrite() .................................................... 100

5.4.2.6 USBD_BULK_GetNumBytesInBuffer() ...................................... 101

5.4.2.7 USBD_BULK_GetNumBytesRemToRead() ..................................102

5.4.2.8 USBD_BULK_GetNumBytesRemToWrite() ................................. 103

5.4.2.9 USBD_BULK_Read() ..............................................................104

5.4.2.10 USBD_BULK_ReadOverlapped() ............................................ 105

5.4.2.11 USBD_BULK_Receive() ........................................................ 106

5.4.2.12 USBD_BULK_SetContinuousReadMode() .................................107

5.4.2.13 USBD_BULK_SetOnRXEvent() ............................................... 108

5.4.2.14 USBD_BULK_SetOnTXEvent() ............................................... 110

5.4.2.15 USBD_BULK_TxIsPending() .................................................. 112

5.4.2.16 USBD_BULK_WaitForRX() .....................................................113

5.4.2.17 USBD_BULK_WaitForTX() .....................................................114

5.4.2.18 USBD_BULK_WaitForTXReady() ............................................ 115

5.4.2.19 USBD_BULK_Write() ............................................................116

5.4.2.20 USBD_BULK_WriteEx() ........................................................ 118

5.4.3 Data structures ............................................................................... 119

5.4.3.1 USB_BULK_INIT_DATA .......................................................... 119

5.4.3.2 USB_BULK_INIT_DATA_EX .....................................................120

5.4.4 Multithreading ................................................................................. 121

5.5 Host API ................................................................................................... 122

5.5.1 Bulk Host API list ............................................................................ 123

5.5.2 USB-Bulk Basic functions ..................................................................125

5.5.2.1 USBBULK_Init() ....................................................................125

5.5.2.2 USBBULK_Exit() ................................................................... 126

5.5.2.3 USBBULK_AddAllowedDeviceItem() ......................................... 127

5.5.2.4 USBBULK_GetNumAvailableDevices() ...................................... 128

5.5.2.5 USBBULK_Open() ................................................................. 129

5.5.2.6 USBBULK_Close() ................................................................. 130

5.5.3 USB-Bulk direct input/output functions ...............................................131

5.5.3.1 USBBULK_Read() ..................................................................131

5.5.3.2 USBBULK_ReadTimed() ......................................................... 132

5.5.3.3 USBBULK_Write() ................................................................. 133

5.5.3.4 USBBULK_WriteTimed() ......................................................... 134

5.5.3.5 USBBULK_CancelRead() ........................................................ 135

5.5.3.6 USBBULK_FlushRx() ..............................................................136

5.5.4 USB-Bulk Control functions ............................................................... 137

5.5.4.1 USBBULK_SetMode() .............................................................137

5.5.4.2 USBBULK_GetMode() ............................................................ 138

5.5.4.3 USBBULK_SetReadTimeout() ..................................................139

5.5.4.4 USBBULK_SetWriteTimeout() ..................................................140

5.5.4.5 USBBULK_ResetPipe() ........................................................... 141

5.5.4.6 USBBULK_ResetDevice() ........................................................142

5.5.5 USB-Bulk general GET functions ........................................................ 143

5.5.5.1 USBBULK_GetVersion() ......................................................... 143

5.5.5.2 USBBULK_GetDevInfo() .........................................................144

5.5.5.3 USBBULK_GetDevInfoByIdx() .................................................145

5.5.5.4 USBBULK_GetUSBId() ........................................................... 146

5.5.5.5 USBBULK_GetProductName() ................................................. 147

5.5.5.6 USBBULK_GetVendorName() .................................................. 148

5.5.5.7 USBBULK_GetSN() ................................................................149

5.5.5.8 USBBULK_GetConfigDescriptor() .............................................150

6 Mass Storage Device Class (MSD) ..........................................................................151

6.1 Overview ................................................................................................... 152

6.2 MSD Configuration ......................................................................................153

6.2.1 Initial configuration ..........................................................................153

6.2.2 Final configuration ........................................................................... 153

6.2.3 MSD class specific configuration functions ...........................................153

6.2.4 Running the example application ....................................................... 153

6.2.4.1 MSD_Start_StorageRAM.c in detail ..........................................154

6.3 Target API ................................................................................................. 155

6.3.1 API functions .................................................................................. 157

6.3.1.1 USBD_MSD_Add() ................................................................ 157

6.3.1.2 USBD_MSD_AddUnit() ...........................................................158

6.3.1.3 USBD_MSD_AddCDRom() ...................................................... 159

6.3.1.4 USBD_MSD_SetPreventAllowRemovalHook() ............................ 160

6.3.1.5 USBD_MSD_SetPreventAllowRemovalHookEx() ......................... 161

6.3.1.6 USBD_MSD_SetReadWriteHook() ............................................ 162

6.3.1.7 USBD_MSD_Task() ................................................................163

6.3.1.8 USBD_MSD_SetStartStopUnitHook() ....................................... 164

6.3.2 Extended API functions .................................................................... 165

6.3.2.1 USBD_MSD_Connect() .......................................................... 165

6.3.2.2 USBD_MSD_Disconnect() .......................................................166

6.3.2.3 USBD_MSD_RequestDisconnect() ............................................167

6.3.2.4 USBD_MSD_RequestRefresh() ................................................ 168

6.3.2.5 USBD_MSD_UpdateWriteProtect() ...........................................169

6.3.2.6 USBD_MSD_WaitForDisconnection() ........................................ 170

6.3.3 Data structures ............................................................................... 171

6.3.3.1 USB_MSD_INIT_DATA ........................................................... 171

6.3.3.2 USB_MSD_INFO ................................................................... 172

6.3.3.3 USB_MSD_INST_DATA .......................................................... 173

6.3.3.4 USB_MSD_LUN_INFO ............................................................ 174

6.3.3.5 PREVENT_ALLOW_REMOVAL_HOOK .........................................175

6.3.3.6 PREVENT_ALLOW_REMOVAL_HOOK_EX ................................... 176

6.3.3.7 READ_WRITE_HOOK ............................................................. 177

6.3.3.8 USB_MSD_INST_DATA_DRIVER .............................................. 178

6.3.3.9 USB_MSD_STORAGE_API ...................................................... 180

6.3.3.10 START_STOP_UNIT_HOOK ................................................... 181

6.4 MSD Storage Driver ....................................................................................182

6.4.1 General information ......................................................................... 182

6.4.1.1 Supported storage types ....................................................... 182

6.4.1.2 Storage drivers supplied with this release ................................ 182

6.4.2 Interface function list .......................................................................182

6.4.3 USB_MSD_STORAGE_API in detail ..................................................... 183

6.4.3.1 USB_MSD_STORAGE_INIT ..................................................... 183

6.4.3.2 USB_MSD_STORAGE_GETINFO ...............................................184

6.4.3.3 USB_MSD_STORAGE_GETREADBUFFER ................................... 185

6.4.3.4 USB_MSD_STORAGE_READ ....................................................186

6.4.3.5 USB_MSD_STORAGE_GETWRITEBUFFER ..................................187

6.4.3.6 USB_MSD_STORAGE_WRITE .................................................. 188

6.4.3.7 USB_MSD_STORAGE_MEDIUMISPRESENT ................................ 189

6.4.3.8 USB_MSD_STORAGE_DEINIT ................................................. 190

7 Smart Mass Storage Component (SmartMSD) ........................................................ 191

7.1 Overview ................................................................................................... 192

7.2 Configuration ............................................................................................. 193

7.2.1 Initial configuration ..........................................................................193

7.2.2 Final configuration ........................................................................... 193

7.2.3 Class specific configuration functions ................................................. 193

7.2.3.1 USB_SMSD_X_Config() ......................................................... 194

7.2.4 Running the example application ....................................................... 194

7.2.5 Calculation of RAM memory usage for SmartMSD ................................ 195

7.3 Target API ................................................................................................. 197

7.3.1 API functions .................................................................................. 198

7.3.1.1 USBD_SMSD_Add() .............................................................. 198

7.3.1.2 USB_SMSD_X_Config() ......................................................... 199

7.3.1.3 USBD_SMSD_AssignMemory() ................................................200

7.3.1.4 USBD_SMSD_SetUserAPI() .................................................... 201

7.3.1.5 USBD_SMSD_SetNumRootDirSectors() .................................... 202

7.3.1.6 USBD_SMSD_SetVolumeInfo() ............................................... 203

7.3.1.7 USBD_SMSD_AddConstFiles() ................................................ 204

7.3.1.8 USBD_SMSD_SetNumSectors() .............................................. 205

7.3.1.9 USBD_SMSD_SetSectorsPerCluster() .......................................206

7.3.2 Data structures ............................................................................... 207

7.3.2.1 USB_SMSD_CONST_FILE ....................................................... 207

7.3.2.2 USB_SMSD_USER_FUNC_API ................................................. 208

7.3.2.3 USB_SMSD_FILE_INFO ..........................................................209

7.3.2.4 USB_SMSD_DIR_ENTRY_SHORT ............................................. 210

7.3.3 Function definitions ..........................................................................212

7.3.3.1 USB_SMSD_ON_READ_FUNC ................................................. 212

7.3.3.2 USB_SMSD_ON_WRITE_FUNC ................................................ 213

7.3.3.3 USB_SMSD_MEM_ALLOC ....................................................... 214

7.3.3.4 USB_SMSD_MEM_FREE ......................................................... 215

8 Media Transfer Protocol Class (MTP) ......................................................................216

8.1 Overview ................................................................................................... 217

8.1.1 Getting access to files ......................................................................218

8.1.2 Additional information ...................................................................... 220

8.2 Configuration ............................................................................................. 221

8.2.1 Initial configuration ..........................................................................221

8.2.2 Final configuration ........................................................................... 221

8.2.3 Class specific configuration ............................................................... 221

8.2.4 Compile time configuration ............................................................... 221

8.3 Running the sample application ....................................................................223

8.3.1 USB_MTP_Start.c in detail ................................................................ 223

8.4 Target API ................................................................................................. 225

8.4.1 API functions .................................................................................. 226

8.4.1.1 USBD_MTP_Add() ................................................................. 226

8.4.1.2 USBD_MTP_AddStorage() ...................................................... 227

8.4.1.3 USBD_MTP_Task() ................................................................ 228

8.4.1.4 USBD_MTP_SendEvent() ....................................................... 229

8.4.2 Data structures ............................................................................... 231

8.4.2.1 USB_MTP_FILE_INFO ............................................................ 231

8.4.2.2 USB_MTP_INIT_DATA ............................................................ 232

8.4.2.3 USB_MTP_INFO .................................................................... 233

8.4.2.4 USB_MTP_INST_DATA ........................................................... 234

8.4.2.5 USB_MTP_INST_DATA_DRIVER ...............................................235

8.4.2.6 USB_MTP_STORAGE_API ....................................................... 236

8.4.2.7 USB_MTP_STORAGE_INFO ..................................................... 238

8.4.3 Enums ........................................................................................... 239

8.4.3.1 USB_MTP_EVENT ..................................................................239

8.5 MTP Storage Driver .................................................................................... 241

8.5.1 General information ......................................................................... 241

8.5.2 Interface function list .......................................................................241

8.5.3 USB_MTP_STORAGE_API in detail ......................................................242

8.5.3.1 USB_MTP_STORAGE_INIT ......................................................242

8.5.3.2 USB_MTP_STORAGE_GET_INFO ..............................................243

8.5.3.3 USB_MTP_STORAGE_FIND_FIRST_FILE ................................... 244

8.5.3.4 USB_MTP_STORAGE_FIND_NEXT_FILE .................................... 245

8.5.3.5 USB_MTP_STORAGE_OPEN_FILE ............................................ 246

8.5.3.6 USB_MTP_STORAGE_CREATE_FILE ......................................... 247

8.5.3.7 USB_MTP_STORAGE_READ_FROM_FILE ...................................248

8.5.3.8 USB_MTP_STORAGE_WRITE_TO_FILE ..................................... 249

8.5.3.9 USB_MTP_STORAGE_CLOSE_FILE ...........................................250

8.5.3.10 USB_MTP_STORAGE_REMOVE_FILE .......................................251

8.5.3.11 USB_MTP_STORAGE_CREATE_DIR ........................................ 252

8.5.3.12 USB_MTP_STORAGE_REMOVE_DIR ....................................... 253

8.5.3.13 USB_MTP_STORAGE_FORMAT ...............................................254

8.5.3.14 USB_MTP_STORAGE_RENAME_FILE .......................................255

8.5.3.15 USB_MTP_STORAGE_DEINIT ................................................ 256

8.5.3.16 USB_MTP_STORAGE_GET_FILE_ATTRIBUTES ..........................257

8.5.3.17 USB_MTP_STORAGE_MODIFY_FILE_ATTRIBUTES .................... 258

8.5.3.18 USB_MTP_STORAGE_GET_FILE_CREATION_TIME .................... 259

8.5.3.19 USB_MTP_STORAGE_GET_FILELAST_WRITE_TIME .................. 260

8.5.3.20 USB_MTP_STORAGE_GET_FILE_ID ........................................261

8.5.3.21 USB_MTP_STORAGE_GET_FILE_SIZE .................................... 262

9 Communication Device Class (CDC) ........................................................................263

9.1 Overview ................................................................................................... 264

9.1.1 Configuration .................................................................................. 264

9.2 The example application ..............................................................................265

9.3 Installing the driver .................................................................................... 266

9.3.1 The .inf file .....................................................................................270

9.3.2 Signing the package ........................................................................ 271

9.3.3 Testing communication to the USB device ...........................................271

9.4 Target API ................................................................................................. 274

9.4.1 Interface function list .......................................................................274

9.4.1.1 USBD_CDC_Add() .................................................................276

9.4.1.2 USBD_CDC_CancelRead() ...................................................... 277

9.4.1.3 USBD_CDC_CancelWrite() ......................................................278

9.4.1.4 USBD_CDC_Read() ............................................................... 279

9.4.1.5 USBD_CDC_ReadOverlapped() ............................................... 280

9.4.1.6 USBD_CDC_Receive() ........................................................... 281

9.4.1.7 USBD_CDC_SetOnBreak() ......................................................282

9.4.1.8 USBD_CDC_SetOnLineCoding() .............................................. 283

9.4.1.9 USBD_CDC_SetOnControlLineState() .......................................284

9.4.1.10 USBD_CDC_SetOnRXEvent() ................................................ 285

9.4.1.11 USBD_CDC_SetOnTXEvent() ................................................ 287

9.4.1.12 USBD_CDC_UpdateSerialState() ........................................... 289

9.4.1.13 USBD_CDC_Write() ............................................................. 290

9.4.1.14 USBD_CDC_WaitForRX() ...................................................... 291

9.4.1.15 USBD_CDC_WaitForTX() ...................................................... 292

9.4.1.16 USBD_CDC_WaitForTXReady() ..............................................293

9.4.1.17 USBD_CDC_WriteSerialState() ..............................................294

9.4.1.18 USBD_CDC_GetNumBytesRemToRead() ................................. 295

9.4.1.19 USBD_CDC_GetNumBytesRemToWrite() ................................. 296

9.4.1.20 USBD_CDC_GetNumBytesInBuffer() ...................................... 297

9.4.2 Data structures ............................................................................... 298

9.4.2.1 USB_CDC_INIT_DATA ............................................................298

9.4.2.2 USB_CDC_LINE_CODING .......................................................299

9.4.2.3 USB_CDC_SERIAL_STATE ...................................................... 300

9.4.2.4 USB_CDC_CONTROL_LINE_STATE ...........................................301

9.4.3 Multithreading ................................................................................. 302

10 Human Interface Device Class (HID) ..................................................................... 303

10.1 Overview ................................................................................................. 304

10.1.1 Further reading ............................................................................. 304

10.1.2 Categories .................................................................................... 304

10.1.2.1 True HIDs .......................................................................... 304

10.1.2.2 Vendor specific HIDs ........................................................... 304

10.2 Background information .............................................................................306

10.2.1 HID descriptors ............................................................................. 306

10.2.1.1 HID descriptor ....................................................................306

10.2.1.2 Report descriptor ................................................................ 306

10.2.1.3 Physical descriptor .............................................................. 307

10.3 Configuration ........................................................................................... 308

10.3.1 Initial configuration ........................................................................ 308

10.3.2 Final configuration ......................................................................... 308

10.4 Example application .................................................................................. 309

10.4.1 USB_HID_Mouse.c ......................................................................... 309

10.4.1.1 Running the example .......................................................... 309

10.4.2 USB_HID_Echo1.c ..........................................................................309

10.4.2.1 Running the example .......................................................... 310

10.4.2.2 Compiling the PC example application ................................... 311

10.5 Target API ............................................................................................... 312

10.5.1 Target interface function list ............................................................313

10.5.2 HID Target API functions ................................................................ 314

10.5.2.1 USBD_HID_Add() ................................................................314

10.5.2.2 USBD_HID_GetNumBytesInBuffer() .......................................315

10.5.2.3 USBD_HID_GetNumBytesRemToRead() .................................. 316

10.5.2.4 USBD_HID_GetNumBytesRemToWrite() ................................. 317

10.5.2.5 USBD_HID_Read() .............................................................. 318

10.5.2.6 USBD_HID_ReadOverlapped() .............................................. 319

10.5.2.7 USBD_HID_WaitForRX() .......................................................320

10.5.2.8 USBD_HID_WaitForTX() .......................................................321

10.5.2.9 USBD_HID_Write() ..............................................................322

10.5.2.10 USBD_HID_SetOnGetReportRequest() ..................................323

10.5.2.11 USBD_HID_SetOnSetReportRequest() .................................. 324

10.5.3 Data structures ............................................................................. 325

10.5.3.1 USB_HID_INIT_DATA .......................................................... 325

10.5.4 Type definitions ............................................................................. 327

10.5.4.1 USB_HID_ON_GETREPORT_REQUEST_FUNC ...........................327

10.5.4.2 USB_HID_ON_SETREPORT_REQUEST_FUNC ........................... 328

10.6 Host API ..................................................................................................329

10.6.1 Host API function list ..................................................................... 330

10.6.2 HID Host API functions ...................................................................331

10.6.2.1 USBHID_Close() ................................................................. 331

10.6.2.2 USBHID_Open() ................................................................. 332

10.6.2.3 USBHID_Init() .................................................................... 333

10.6.2.4 USBHID_Exit() ................................................................... 334

10.6.2.5 USBHID_GetNumAvailableDevices() .......................................335

10.6.2.6 USBHID_GetProductName() ................................................. 336

10.6.2.7 USBHID_GetInputReportSize() ..............................................337

10.6.2.8 USBHID_GetOutputReportSize() ............................................338

10.6.2.9 USBHID_GetProductId() .......................................................339

10.6.2.10 USBHID_GetVendorId() ......................................................340

10.6.2.11 USBHID_RefreshList() ........................................................341

10.6.2.12 USBHID_SetVendorPage() .................................................. 342

11 Printer Class ........................................................................................................... 343

11.1 Overview ................................................................................................. 344

11.1.1 Configuration ................................................................................ 344

11.2 The example application ............................................................................ 345

11.3 Target API ............................................................................................... 347

11.3.1 Interface function list ..................................................................... 347

11.3.2 API functions ................................................................................ 348

11.3.2.1 USB_PRINTER_Init() ........................................................... 348

11.3.2.2 USB_PRINTER_Task() .......................................................... 349

11.3.2.3 USB_PRINTER_TaskEx() .......................................................350

11.3.2.4 USB_PRINTER_ConfigIRQProcessing() ....................................351

11.3.2.5 USB_PRINTER_Read() ......................................................... 352

11.3.2.6 USB_PRINTER_ReadTimed() ................................................. 353

11.3.2.7 USB_PRINTER_Receive() ......................................................354

11.3.2.8 USB_PRINTER_ReceiveTimed() ............................................. 355

11.3.2.9 USB_PRINTER_Write() ......................................................... 356

11.3.2.10 USB_PRINTER_WriteTimed() ............................................... 357

11.3.2.11 USB_PRINTER_API ............................................................ 358

11.4 Printer API ...............................................................................................359

11.4.1 General information ....................................................................... 359

11.4.2 USB_PRINTER_API in detail ............................................................ 360

11.4.2.1 USB_PRINTER_GET_DEVICE_ID_STRING ............................... 360

11.4.2.2 USB_PRINTER_ON_DATA_RECEIVED ......................................361

11.4.2.3 USB_PRINTER_GET_HAS_NO_ERROR .................................... 362

11.4.2.4 USB_PRINTER_GET_IS_SELECTED ........................................ 363

11.4.2.5 USB_PRINTER_GET_IS_PAPER_EMPTY ................................... 364

11.4.2.6 USB_PRINTER_ON_RESET ....................................................365

12 IP-over-USB (IP) .....................................................................................................366

12.1 Overview ................................................................................................. 367

12.2 Using only RNDIS or CDC-ECM ...................................................................368

12.2.1 Working with emUSB-Device-IP ....................................................... 368

12.3 Configuration ........................................................................................... 370

12.3.1 Initial Configuration ....................................................................... 370

12.3.2 Final configuration ......................................................................... 370

12.3.3 Class specific configuration ............................................................. 370

12.4 Running the sample application .................................................................. 371

12.4.1 IP_Config_IP_over_USB.c in detail ................................................... 371

12.5 emUSB-Device-IP + embOS/IP as a "USB Webserver" ................................... 374

12.6 Target API ............................................................................................... 375

12.6.1 API functions ................................................................................ 376

12.6.1.1 USBD_IP_Add() .................................................................. 376

12.6.1.2 USBD_IP_Task() ................................................................. 377

12.6.2 Data structures ............................................................................. 378

12.6.2.1 USB_IP_INIT_DATA ............................................................. 378

13 Remote NDIS (RNDIS) ...........................................................................................379

13.1 Overview ................................................................................................. 380

13.1.1 Working with RNDIS ...................................................................... 380

13.1.2 Additional information .................................................................... 380

13.2 Configuration ........................................................................................... 381

13.2.1 Initial Configuration ....................................................................... 381

13.2.2 Final configuration ......................................................................... 381

13.2.3 Class specific configuration ............................................................. 381

13.3 Running the sample application .................................................................. 382

13.3.1 IP_Config_RNDIS.c in detail ............................................................ 382

13.4 RNDIS + embOS/IP as a "USB Webserver" .................................................. 384

13.5 Target API ............................................................................................... 385

13.5.1 API functions ................................................................................ 386

13.5.1.1 USBD_RNDIS_Add() ............................................................386

13.5.1.2 USBD_RNDIS_Task() ........................................................... 387

13.5.1.3 USBD_RNDIS_SetDeviceInfo() ..............................................388

13.5.2 Data structures ............................................................................. 389

13.5.2.1 USB_RNDIS_INIT_DATA .......................................................389

13.5.2.2 USB_RNDIS_DEVICE_INFO .................................................. 390

13.5.3 Driver interface ............................................................................. 391

13.5.3.1 USB_IP_NI_DRIVER_API ...................................................... 391

13.5.3.2 USB_IP_NI_DRIVER_DATA ................................................... 392

13.6 RNDIS IP Driver ....................................................................................... 393

13.6.1 General information ....................................................................... 393

13.6.2 Interface function list ..................................................................... 393

13.6.3 USB_IP_NI_DRIVER_API in detail .................................................... 394

13.6.3.1 USB_IP_NI_INIT ................................................................. 394

13.6.3.2 USB_IP_NI_GET_PACKET_BUFFER .........................................395

13.6.3.3 USB_IP_NI_WRITE_PACKET ................................................. 396

13.6.3.4 USB_IP_NI_SET_PACKET_FILTER .......................................... 397

13.6.3.5 USB_IP_NI_GET_LINK_STATUS .............................................398

13.6.3.6 USB_IP_NI_GET_LINK_SPEED .............................................. 399

13.6.3.7 USB_IP_NI_GET_HWADDR ................................................... 400

13.6.3.8 USB_IP_NI_GET_STATS ....................................................... 401

13.6.3.9 USB_IP_NI_GET_MTU ..........................................................402

13.6.3.10 USB_IP_NI_RESET ............................................................ 403

13.6.3.11 USB_IP_NI_SET_WRITE_PACKET_FUNC ............................... 404

14 CDC-ECM ............................................................................................................... 405

14.1 Overview ................................................................................................. 406

14.1.1 Working with CDC-ECM .................................................................. 406

14.1.2 Additional information .................................................................... 407

14.2 Configuration ........................................................................................... 408

14.2.1 Initial configuration ........................................................................ 408

14.2.2 Final configuration ......................................................................... 408

14.3 Running the sample application .................................................................. 409

14.3.1 IP_Config_ECM.c in detail ............................................................... 409

14.4 Target API ............................................................................................... 411

14.4.1 API functions ................................................................................ 412

14.4.1.1 USBD_ECM_Add() ............................................................... 412

14.4.1.2 USBD_ECM_Task() .............................................................. 413

14.4.2 Data structures ............................................................................. 414

14.4.2.1 USB_ECM_INIT_DATA ..........................................................414

14.4.3 Driver interface ............................................................................. 415

14.4.3.1 USB_IP_NI_DRIVER_API ...................................................... 415

14.4.3.2 USB_IP_NI_DRIVER_DATA ................................................... 416

14.5 CDC-ECM IP Driver ................................................................................... 417

14.5.1 General information ....................................................................... 417

14.5.2 Interface function list ..................................................................... 417

14.5.3 USB_IP_NI_DRIVER_API in detail .................................................... 418

14.5.3.1 USB_IP_NI_INIT ................................................................. 418

14.5.3.2 USB_IP_NI_GET_PACKET_BUFFER .........................................419

14.5.3.3 USB_IP_NI_WRITE_PACKET ................................................. 420

14.5.3.4 USB_IP_NI_SET_PACKET_FILTER .......................................... 421

14.5.3.5 USB_IP_NI_GET_LINK_STATUS .............................................422

14.5.3.6 USB_IP_NI_GET_LINK_SPEED .............................................. 423

14.5.3.7 USB_IP_NI_GET_HWADDR ................................................... 424

14.5.3.8 USB_IP_NI_GET_STATS ....................................................... 425

14.5.3.9 USB_IP_NI_GET_MTU ..........................................................426

14.5.3.10 USB_IP_NI_RESET ............................................................ 427

14.5.3.11 USB_IP_NI_SET_WRITE_PACKET_FUNC ............................... 428

15 Audio .......................................................................................................................429

15.1 Overview ................................................................................................. 430

15.2 Introduction ............................................................................................. 431

15.3 Configuration ........................................................................................... 432

15.3.1 Initial configuration ........................................................................ 432

15.3.2 Final configuration ......................................................................... 432

15.3.3 Using the microphone interface ....................................................... 432

15.3.4 Using the speaker interface ............................................................ 433

15.4 Target API ............................................................................................... 434

15.4.1 API functions ................................................................................ 435

15.4.1.1 USBD_AUDIO_Add() ............................................................435

15.4.1.2 USBD_AUDIO_Read_Task() .................................................. 436

15.4.1.3 USBD_AUDIO_Write_Task() ..................................................437

15.4.1.4 USBD_AUDIO_Start_Play() ...................................................438

15.4.1.5 USBD_AUDIO_Stop_Play() ................................................... 439

15.4.1.6 USBD_AUDIO_Start_Listen() ................................................ 440

15.4.1.7 USBD_AUDIO_Stop_Listen() .................................................441

15.4.2 Data structures ............................................................................. 442

15.4.2.1 USBD_AUDIO_INIT_DATA .................................................... 442

15.4.2.2 USBD_AUDIO_MIC_CONF .....................................................444

15.4.2.3 USBD_AUDIO_SPEAKER_CONF ............................................. 445

15.4.3 Function definitions ........................................................................ 446

15.4.3.1 USBD_AUDIO_TX_FUNC ...................................................... 446

15.4.3.2 USBD_AUDIO_RX_FUNC ...................................................... 447

15.4.3.3 USBD_AUDIO_CONTROL_FUNC .............................................449

16 Combining USB components (Multi-Interface) ........................................................451

16.1 Overview ................................................................................................. 452

16.1.1 Single interface device classes ........................................................ 453

16.1.2 Multiple interface device classes ...................................................... 453

16.1.3 IAD class ...................................................................................... 454

16.2 Configuration ........................................................................................... 455

16.3 How to combine ....................................................................................... 456

16.4 emUSB-Device component specific modification ............................................ 460

16.4.1 BULK component ........................................................................... 460

16.4.1.1 Device side ........................................................................ 460

16.4.1.2 Host side ........................................................................... 460

16.4.2 MSD component ............................................................................ 460

16.4.2.1 Device side ........................................................................ 460

16.4.2.2 Host side ........................................................................... 460

16.4.3 HID component ............................................................................. 460

16.4.3.1 Device side ........................................................................ 460

16.4.3.2 Host side ........................................................................... 460

16.4.4 CDC component ............................................................................ 461

16.4.4.1 Device side ........................................................................ 461

16.4.4.2 Host side ........................................................................... 461

16.5 MSD and MTP combination feature ............................................................. 463

16.5.1 Configuration ................................................................................ 463

16.5.2 Limitations .................................................................................... 464

16.5.3 Target API .................................................................................... 465

16.5.3.1 USBD_MSD_MTP_Add() ....................................................... 466

16.5.3.2 USBD_MSD_MTP_GetMode() ................................................ 467

16.5.3.3 USBD_MSD_MTP_Task() ...................................................... 468

17 Target OS Interface ................................................................................................469

17.1 General information .................................................................................. 470

17.1.1 Operating system support supplied with this release ...........................470

17.2 Interface function list ................................................................................ 471

17.2.0.1 USB_OS_DeInit() ................................................................472

17.2.0.2 USB_OS_Delay() ................................................................ 473

17.2.0.3 USB_OS_DecRI() ................................................................ 474

17.2.0.4 USB_OS_GetTickCnt() ......................................................... 475

17.2.0.5 USB_OS_IncDI() .................................................................476

17.2.0.6 USB_OS_Init() ................................................................... 477

17.2.0.7 USB_OS_Panic() ................................................................. 478

17.2.0.8 USB_OS_Signal() ................................................................479

17.2.0.9 USB_OS_Wait() .................................................................. 480

17.2.0.10 USB_OS_WaitTimed() ........................................................ 481

17.3 Example .................................................................................................. 482

18 Target USB Driver .................................................................................................. 485

18.1 General information .................................................................................. 486

18.1.1 Available USB drivers ..................................................................... 486

18.2 Adding a driver to emUSB-Device ...............................................................487

18.2.1 USBD_X_Config() ...........................................................................487

19 Support ....................................................................................................................489

19.1 Contacting support ................................................................................... 490

20 Profiling with SystemView .......................................................................................491

20.1 Profiling overview ..................................................................................... 492

20.2 Additional files for profiling ........................................................................ 493

20.2.1 Additional files on target side ..........................................................493

20.2.2 Additional files on PC side .............................................................. 493

20.3 Enable profiling ........................................................................................ 494

20.4 Recording and analyzing profiling information ...............................................495

21 Debugging ...............................................................................................................496

21.1 Message output ........................................................................................ 497

21.2 API functions ........................................................................................... 498

21.2.1 USBD_AddLogFilter() ......................................................................499

21.2.2 USBD_AddWarnFilter() ................................................................... 500

21.2.3 USBD_SetLogFilter() ...................................................................... 501

21.2.4 USBD_SetWarnFilter() .................................................................... 502

21.2.5 USB_PANIC ................................................................................... 503

21.2.6 USB_X_Log() ................................................................................ 504

21.2.7 USB_X_Warn() .............................................................................. 505

21.3 Message types ......................................................................................... 506

22 Certification ............................................................................................................. 508

22.1 What is the Windows Hardware Certification and why do I need it? ..................509

22.2 Certification offer ......................................................................................509

22.3 Vendor and Product ID ..............................................................................509

22.4 Certification without SEGGER Microcontroller ................................................510

23 Performance & resource usage ..............................................................................511

23.1 Memory footprint ......................................................................................512

23.2 Performance .............................................................................................514

24 FAQ .........................................................................................................................515

Chapter 1

Introduction

This chapter will give a short introduction to emUSB-Device, including the supported USB

classes and components. Host and target requirements are covered as well.

1.1 Overview

This guide describes how to install, configure and use emUSB-Device. It also explains the

internal structure of emUSB-Device.

emUSB-Device has been designed to work on any embedded system with a USB client

controller. It can be used with USB 1.1 or USB 2.0 devices.

The highest possible transfer rate on USB 2.0 full speed (12 Mbit/s) devices is approximately

1 MB/s. This data rate can indeed be achieved on fast systems, such as Cortex-M devices

running at 48 MHz and above.

USB 2.0 high speed mode (480 MBit/s) is also fully supported and is automatically handled.

Using USB high speed mode with an Cortex-M or faster could achieve values of approx.

40 MB/s.

The USB standard defines four types of communication: Control, isochronous, interrupt,

and bulk. Experience shows that for most embedded devices the bulk mode is the commu-

nication mode of choice because applications can utilize the full bandwidth of the Universal

Serial Bus.

20 CHAPTER 1 emUSB-Device features

1.2 emUSB-Device features

Key features of emUSB-Device are:

• High performance

• Can be used with or without an RTOS

• Easy to use

• Easy to port

• No custom USB host driver necessary

• Start / test application supplied

• Highly efficient, portable, and commented ANSI C source code

• Hardware abstraction layer allows rapid addition of support for new devices

21 CHAPTER 1 emUSB-Device components

1.3 emUSB-Device components

emUSB-Device consists of three layers: A driver for hardware access, the emUSB-Device

core and at least a USB class driver or the bulk communication component.

The different available hardware drivers, the USB class drivers, and the bulk communication

component are additional packages, which can be combined and ordered as they fit to the

requirements of your project. Normally, emUSB-Device consists of a driver that fits to the

used hardware, the emUSB-Device core and at least one of the USB class drivers.

Component Description

USB protocol layer

Bulk emUSB-Device bulk component.

MSD emUSB-Device Mass Storage Device class component.

IP-over-USB emUSB-Device IP-over-USB component.

SmartMSD emUSB-Device SmartMSD Component

CDC-ACM emUSB-Device Communication Device Class component.

HID emUSB-Device Human Interface Device Class component.

MTP emUSB-Device Media Transfer Protocol component.

Printer emUSB-Device Printer Class component.

RNDIS emUSB-Device RNDIS component.

CDC-ECM emUSB-Device CDC Ethernet Control Model component.

UVC emUSB-Device USB video class.

Core layer

emUSB-Device-Core The emUSB-Device core is the intrinsic USB stack.

Hardware layer

Driver USB controller driver.

1.3.1 emUSB-Device-Bulk

emUSB-Device-Bulk allows you to quickly and smoothly develop software for an embedded

device that communicates with a PC via USB. The communication is like a single, high-

speed, reliable channel (very similar to a TCP connection). This bidirectional channel, with

built-in flow control, allows the PC to send data to the embedded target, the embedded

target to receive these bytes and reply with any number of bytes. The PC is the USB host,

the target is the USB client.

1.3.2 emUSB-Device-MSD

1.3.2.1 Purpose of emUSB-Device-MSD

Access the target device like an ordinary disk drive

emUSB-Device-MSD enables the use of an embedded target device as a USB mass storage

device. The target device can be simply plugged-in and used like an ordinary disk drive,

without the need to develop a driver for the host operating system. This is possible because

the mass storage class is one of the standard device classes, defined by the USB Imple-

menters Forum (USB IF). Virtually every major operating system on the market supports

these device classes out of the box.

No custom host drivers necessary

Every major OS already provides host drivers for USB mass storage devices, there is no

need to implement your own. The target device will be recognized as a mass storage device

and can be accessed directly.

22 CHAPTER 1 emUSB-Device components

Plug and Play

Assuming the target system is a digital camera using emUSB-Device-MSD, videos or photos

taken by this camera can be conveniently accessed with the file system explorer of the

used operating system when the camera is connected to the computer.

1.3.2.2 Typical applications

Typical applications are:

• Digital camera

• USB stick

• MP3 Player

• DVD player

Any target with USB interface: easy access to configuration and data files

1.3.2.3 emUSB-Device-MSD features

Key features of emUSB-Device-MSD are:

• Can be used with RAM, parallel flash, serial flash or mechanical drives

• Support for full speed (12 Mbit/s) and high speed (480 Mbit/s) transfer rates

• OS-abstraction: Can be used with any RTOS, but no OS is required for MSD-only devices

1.3.2.4 How does it work?

Use file system support from host OS

A device which uses emUSB-Device-MSD will be recognized as a mass storage device and

can be used like an ordinary disk drive. If the device is unformatted when plugged-in, the

host operating system will ask you to format the device. Any file system provided by the

host can be used. Typically FAT is used, but other file systems such as NTFS are possible,

too. If one of those file systems is used, the host is able to read from and write to the

device using the storage functions of the emUSB-Device MSD component, which define

unstructured read and write operations. Thus, there is no need to develop extra file system

code if the application only accesses data on the target from the host side. This is typically

the case for simple storage applications, such as USB memory sticks or ATA to USB bridges.

Only provide file system code on the target if necessary

Mass storage devices like USB sticks do not require their own file system implementation.

File system program code is only required if the application running on the target device

has to access the stored data. The development of a file system is a complex and time-

consuming task and increases the time-to market. Thus we recommend the use of a com-

mercial file system like emFile, SEGGER’s file system for embedded applications. emFile

is a high performance library that is optimized for minimum memory consumption in RAM

and ROM, high speed and versatility. It is written in ANSI C and runs on any CPU and on

any media. Refer to www.segger.com/emfile.html for more information about emFile.

23 CHAPTER 1 emUSB-Device components

1.3.3 emUSB-Device IP-over-USB

emUSB-Device IP-over-USB allows to run any IP-based protocol over USB. This component

combines the advantages of RNDIS and CDC-ECM and allows plug-and-play on any major

host operating system. Using the IP-over-USB technology in combination with a built in

web server, the device can easily be accessed from any host (Windows, Linux, Mac) by

simply typing the device name into the web browser.

1.3.3.1 Typical applications

Typical applications are:

• Headphones

• Printer

• Data logger

• Ethernet2USB adapter

1.3.4 emUSB-Device-SmartMSD

The emUSB-Device-SmartMSD component allows to easily stream files to and from USB

devices. Once the USB device is connected to the host, files can be read or written to the

application without the need for dedicated storage memory.

1.3.4.1 Typical applications

Typical applications are:

• Updating firmware (e.g. Handheld Terminal)

• Updating configuration files

1.3.5 emUSB-Device-CDC

emUSB-Device-CDC converts the target device into a serial communication device. A tar-

get device running emUSB-Device-CDC is recognized by the host as a serial interface

(USB2COM, virtual COM port), without the need to install a special host driver, because the

communication device class is one of the standard device classes and every major operat-

ing system already provides host drivers for those device classes. All PC software using a

COM port will work without modifications with this virtual COM port.

1.3.5.1 Typical applications

Typical applications are:

• Modem

• Telephone system

• Fax machine

1.3.6 emUSB-Device-HID

The Human Interface Device class (HID) is an abstract USB class protocol defined by the

USB Implementers Forum. This protocol was defined for handling devices that humans use

to control the operation of computer systems. An installation of a custom host USB driver

is not necessary because the USB human interface device class is standardized and every

major OS already provides host drivers for it.

1.3.6.1 Typical applications

Typical applications are:

• Keyboard

• Mouse and similar pointing devices

• Gamepad

• Front-panel controls - for example, switches and buttons

24 CHAPTER 1 emUSB-Device components

• Bar-code reader

• Thermometer

• Voltmeter

• Low-speed JTAG emulator

• Uninterruptible power supply (UPS)

1.3.7 emUSB-Device-MTP

The Media Transfer Protocol (MTP) is a USB class protocol which can be used to transfer

files to and from storage devices. MTP is an alternative to MSD as it operates on a file level

rather than on a storage sector level. The advantage of MTP is the ability to access the

storage medium from the host PC and from the device at the same time. Because MTP

works at the file level this also eliminates the risk of damaging the file system when the

communication to the host has been canceled unexpectedly (e.g. the cable was removed).

MTP is supported by most operating systems without the need to install third-party drivers.

1.3.7.1 Typical applications

Typical applications are:

• Digital camera

• USB stick

• MP3 Player

• DVD player

• Telephone

Any target with USB interface: easy access to configuration and data files.

1.3.8 emUSB-Device-Printer

emUSB-Device-Printer converts the target device into a printing device. A target device

running emUSB-Device-Printer is recognized by the host as a printer. Unless the device

identifies itself as a printer already recognized by the host PC, you must install a driver to

be able to communicate with the USB device.

1.3.8.1 Typical applications

Typical applications are:

• Laser/Inkjet printer

• CNC machine

1.3.9 emUSB-Device-RNDIS

emUSB-Device-RNDIS allows to create a virtual Ethernet adapter through which the host

PC can communicate with the device using the Internet protocol suite (TCP, UDP, FTP, HTTP,

Telnet). This allows the creation of USB based devices which can host a webserver or

act as a telnet terminal or a FTP server. emUSB-Device-RNDIS offer a unique customer

experience and allows to save development and hardware cost by e.g. using a website as

a user interface instead of creating an application for every major OS and by eliminating

the Ethernet hardware components from your device.

1.3.9.1 Typical applications

Typical applications are:

• USB-Webserver

• USB-Terminal (e.g. Telnet)

• USB-FTP-Server

25 CHAPTER 1 emUSB-Device components

1.3.10 emUSB-Device-CDC-ECM

emUSB-Device-CDC-ECM allows to create a virtual Ethernet adapter through which the

host PC can communicate with the device using the Internet protocol suite (TCP, UDP, FTP,

HTTP, Telnet). This allows the creation of USB based devices which can host a webserver or

act as a telnet terminal or a FTP server. emUSB-Device-CDC-ECM offer a unique customer

experience and allows to save development and hardware cost by e.g. using a website as

a user interface instead of creating an application for every major OS and by eliminating

the Ethernet hardware components from your device.

1.3.10.1 Typical applications

Typical applications are:

• USB-Webserver

• USB-Terminal (e.g. Telnet)

• USB-FTP-Server

26 CHAPTER 1 Requirements

1.4 Requirements

1.4.1 Target system

Hardware

The target system must have a USB controller. The memory requirements can be found in

the chapter Performance & resource usage on page 511. In order to have the control when

the device is enumerated by the host, a switchable attach is necessary. This is a switchable

pull-up connected to the D+ Line of USB.

Software

emUSB-Device is optimized to be used with embOS but works with any other supported

RTOS or without an RTOS in a superloop. For information regarding the OS integration refer

to the chapter Target OS Interface on page 469.

1.4.2 Development environment (compiler)

The CPU used is of no importance; only an ANSI-compliant C compiler complying with at

least one of the following international standard is required:

• ISO/IEC/ANSI 9899:1990 (C90) with support for C++ style comments (//)

• ISO/IEC 9899:1999 (C99)

• ISO/IEC 14882:1998 (C++)

If your compiler has some limitations, let us know and we will inform you if these will be

a problem when compiling the software. Any compiler for 16/32/64-bit CPUs or DSPs that

we know of can be used.

A C++ compiler is not required, but can be used. The application program can therefore

also be programmed in C++ if desired.

27 CHAPTER 1 File structure

1.5 File structure

The following table shows the contents of the emUSB-Device root directory:

Directory Contents

Application Contains the application programs. Depending on which stack is

used, several files are available for each stack. Detailed informa-

tion can be found in the corresponding chapter.

BSP Contains example hardware-specific configurations for different

eval boards.

Config Contains configuration files (USB_Conf.h, USB_ConfigIO.c).

Doc Contains the emUSB-Device documentation.

Inc Contains include files.

Sample Contains operating systems dependent files which allows to run

emUSB-Device with different RTOS’s.

SEGGER Contains generic routines from SEGGER (e.g. memcpy).

USB Contains the emUSB-Device source code.

Windows Contains Windows specific applications which can be used in con-

junction with the device application samples.

Chapter 2

Background information

This is a short introduction to USB. The fundamentals of USB are explained and links to

additional resources are given.

Information provided in this chapter is not required to use the software.

29 CHAPTER 2 USB

2.1 USB

2.1.1 Short Overview

The Universal Serial Bus (USB) is a bus architecture for connecting multiple peripherals to a

host computer. It is an industry standard — maintained by the USB Implementers Forum —

and because of its many advantages it enjoys a huge industry-wide acceptance. Over the

years, a number of USB-capable peripherals appeared on the market, for example printers,

keyboards, mice, digital cameras etc. Among the top benefits of USB are:

• Excellent plug-and-play capabilities allow devices to be added to the host system

without reboots (“hot-plug”). Plugged-in devices are identified by the host and the

appropriate drivers are loaded instantly.

• USB allows easy extensions of host systems without requiring host-internal extension

cards.

• Device bandwidths may range from a few kB/s to hundreds of MB/s.

• A wide range of packet sizes and data transfer rates are supported.

• USB provides internal error handling. Together with the already mentioned hot-plug

capability this greatly improves robustness.

• The provisions for powering connected devices dispense the need for extra power

supplies for many low power devices.

• Several transfer modes are supported which ensures the wide applicability of USB.

These benefits did not only lead to broad market acceptance, but it also added several

advantages, such as low costs of USB cables and connectors or a wide range of USB stack

implementations. Last but not least, the major operating systems such as Microsoft Win-

dows, Mac OS X, or Linux provide excellent USB support.

2.1.2 Important USB Standard Versions

USB 1.1 (September 1998)

This standard version supports isochronous and asynchronous data transfers. It has dual

speed data transfer of 1.5 Mbit/s for low speed and 12 Mbit/s for full speed devices. The

maximum cable length between host and device is five meters. Up to 500 mA of electric

current may be distributed to low power devices.

USB 2.0 (April 2000)

As all previous USB standards, USB 2.0 is fully forward and backward compatible. Existing

cables and connectors may be reused. A new high speed transfer speed of 480 Mbit/s (40

times faster than USB 1.1 at full speed) was added.

USB 3.0 (November 2008)

As all previous USB standards, USB 3.0 is fully forward and backward compatible. Exist-

ing cables and connectors may be reused but the new speed can only be used with new

USB 3.0 cables and devices. The new speed class is named USB Super-Speed, which offers

a maximum rate of 5 Gbit/s.

USB 3.1 (July 2013)

As all previous USB standards, USB 3.1 is fully forward and backward compatible. The new

specification replaces the 3.0 standard and introduces new transfer speeds of up to 10

Gbit/s.

30 CHAPTER 2 USB

2.1.3 USB System Architecture

A USB system is composed of three parts - a host side, a device side and a physical bus.

The physical bus is represented by the USB cable and connects the host and the device.

The USB system architecture is asymmetric. Every single host can be connected to multiple

devices in a tree-like fashion using special hub devices. You can connect up to 127 devices

to a single host, but the count must include the hub devices as well.

A USB host consists of a USB host controller hardware and a layered software stack. This

host stack contains:

• A host controller driver (HCD) which provides the functionality of the host controller

hardware.

• The USB Driver (USBD) Layer which implements the high level functions used by USB

device drivers in terms of the functionality provided by the HCD.

• The USB Device drivers which establish connections to USB devices. The driver classes

are also located here and provide generic access to certain types of devices such as

printers or mass storage devices.

31 CHAPTER 2 USB

USB Device

Two types of devices exist: hubs and functions. Hubs provide for additional USB attachment

points. Functions provide capabilities to the host and are able to transmit or receive data

or control information over the USB bus. Every peripheral USB device represents at least

one function but may implement more than one function. A USB printer for instance may

provide file system like access in addition to printing.

In this guide we treat the term USB device as synonymous with functions and will not

consider hubs.

Each USB device contains configuration information which describes its capabilities and

resource requirements. A USB device must be configured by the host before its functions can

be used. When a new device is connected for the first time, the host enumerates it, requests

the configuration from the device, and performs the actual configuration. For example, if

an embedded device uses emUSB-Device-MSD, the embedded device will appear as a USB

mass storage device, and the host OS provides the driver out of the box. In general, there

is no need to develop a custom driver to communicate with target devices that use one

of the USB class protocols.

Descriptors

A device reports its attributes via descriptors. Descriptors are data structures with a stan-

dard defined format. A USB device has one device descriptor which contains information

applicable to the device and all of its configurations. It also contains the number of config-

urations the device supports. For each configuration, a configuration descriptor contains

configuration-specific information. The configuration descriptor also contains the number

of interfaces provided by the configuration. An interface groups the endpoints into logi-

cal units. Each interface descriptor contains information about the number of endpoints.

Each endpoint has its own endpoint descriptor which states the endpoint’s address, transfer

types etc.

As can be seen, the descriptors form a tree. The root is the device descriptor with n con-

figuration descriptors as children, each of which has m interface descriptors which in turn

have o endpoint descriptors each.

32 CHAPTER 2 USB

2.1.4 Transfer Types

The USB standard defines four transfer types: control, isochronous, interrupt, and bulk.

Control transfers are used in the setup phase. The application can select one of the other

three transfer types. For most embedded applications, bulk is the best choice because it

allows the highest possible data rates.

Control transfers

Typically used for configuring a device when attached to the host. It may also be used for

other device-specific purposes, including control of other pipes on the device.

Isochronous transfers

Typically used for applications which need guaranteed speed. Isochronous transfer is fast

but with possible data loss. A typical use is for audio data which requires a constant data

rate.

Interrupt transfers

Typically used by devices that need guaranteed quick responses (bounded latency).

Bulk transfers

Typically used by devices that generate or consume data in relatively large and bursty

quantities. Bulk transfer has wide dynamic latitude in transmission constraints. It can use all

remaining available bandwidth, but with no guarantees on bandwidth or latency. Because

the USB bus is normally not very busy, there is typically 90% or more of the bandwidth

available for USB transfers.

2.1.5 Setup phase / Enumeration

The host first needs to get information from the target, before the target can start commu-

nicating with the host. This information is gathered in the initial setup phase. The informa-

tion is contained in the descriptors, which are in the configurable section of the USB-MSD

stack. The most important part of target device identification are the Product and Vendor

IDs. During the setup phase, the host also assigns an address to the client. This part of

the setup is called enumeration.

2.1.6 Product / Vendor IDs

The Product and Vendor IDs are necessary to identify the USB device. The Product ID

describes a specific device type and does not need to be unique between different devices of

the same type. USB host systems like Windows use the Product ID/Vendor ID combination

to identify which drivers are needed.

For example: all our J-Link devices have the Vendor ID 0x1366 and Product ID 0x0105.

A Vendor and Product ID is necessary only when development of the product is finished;

during the development phase, the supplied Vendor and Product IDs can be used as sam-

ples. Using the sample Vendor ID (0x8765) or the SEGGER Vendor ID in a finished product

is not allowed.

Possible options to obtain a Vendor ID or Product ID are described in the chapter Vendor

and Product ID on page 509.

33 CHAPTER 2 Predefined device classes

2.2 Predefined device classes

The USB Implementers Forum has defined device classes for different purposes. In general,

every device class defines a protocol for a particular type of application such as a mass

storage device (MSD), human interface device (HID), etc. Device classes provide a stan-

dardized way of communication between host and device and typically work with a class

driver which comes with the host operating system.

Using a predefined device class where applicable minimizes the amount of work to make

a device usable on different host systems.

34 CHAPTER 2 USB hardware analyzers

2.3 USB hardware analyzers

A variety of USB hardware analyzers are on the market with different capabilities. If you

are developing an application using emUSB-Device it should not be necessary to have a

USB analyzer, but we still recommend you do.

35 CHAPTER 2 References

2.4 References

For additional information see the following documents:

• Universal Serial Bus Specification, Revision 2.0

• Universal Serial Bus Mass Storage Class Specification Overview, Rev 1.2

• UFI command specification: USB Mass Storage Class, UFI Command Specification, Rev

1.0

Chapter 3

Getting started

The first step in getting emUSB-Device up and running is typically to compile it for the

target system and to run it in the target system. This chapter explains how to do this.

37 CHAPTER 3 How to setup your target system

3.1 How to setup your target system

We assume that you are familiar with the tools you have selected for your project (compiler,

project manager, linker, etc.). You should therefore be able to add files, add directories to

the include search path, and so on. In this document the Embedded Studio IDE is used for

all examples and screenshots, but every other ANSI C toolchain can also be used. It is also

possible to use makefiles; in this case, when we say “add to the project”, this translates

into “add to the makefile”.

Procedure to follow

Integration of emUSB-Device is a relatively simple process, which consists of the following

steps:

• Take a running project for your target hardware.

• Add emUSB-Device files to the project.

• Add hardware dependent configuration to the project.

• Prepare and run the application.

3.1.1 Take a running project

The project to start with should include the setup for basic hardware (e.g. CPU, PLL, DDR

SDRAM) and initialization of the RTOS. emUSB-Device is designed to be used with embOS,

SEGGER’s real-time operating system. We recommend to start with an embOS sample

project and include emUSB-Device into this project.

3.1.2 Add emUSB-Device files

Add all source files in the USB folder to your project. It it not necessary to select files

depending on your configuration. Simply add all files, the linker will drop everything not

needed.

Add RTOS layer

Additionally add the RTOS interface layer to your project. Choose a file from the folder

Sample/USB/OS that matches your RTOS. For embOS use USBH_OS_embOS.c. There is also

a file USB_OS_None.c containing a layer to be used for superloop applications without an

RTOS.

Configuring the include path

The include path is the path in which the compiler looks for include files. In cases where

the included files (typically header files, .h) do not reside in the same folder as the C file to

compile, an include path needs to be set. In order to build the project with all added files,

you will need to add the following directories to your include path:

•Config

•Inc

•SEGGER

•USB

3.1.3 Configuring debugging output

While developing and testing emUSB-Device, we recommend to use the DEBUG configu-

ration of emUSB-Device. This is enabled by setting the preprocessor symbol DEBUG to 1

(or USB_DEBUG_LEVEL to 2). The DEBUG configuration contains many additional run-time

checks and generate debug output messages which are very useful to identify problems

that may occur during development. In case of a fatal problem (e.g. an invalid configu-

ration) the program will end up in the function USB_OS_Panic() with a appropriate error

message that describes the cause of the problem. Once the application is running correctly,

DEBUG can be set to 0.

38 CHAPTER 3 How to setup your target system

Add the file USB_ConfigIO.c found in the folder Config to your project and configure it to

match the message output method used by your debugging tools. If possible use RTT.

To later compile a release configuration, which has a significant smaller code footprint,

simply set the preprocessor symbol DEBUG (or USB_DEBUG_LEVEL) to 0.

3.1.4 Add hardware dependent configuration

To perform target hardware dependent runtime configuration, the emUSB-Device stack calls

a function named USBD_X_Config. Typical tasks that may be done inside this function are:

• Select an appropriate driver for the USB controller.

• Configure I/O pins of the MCU for USB.

• Configure PLL and clock divider necessary for USB operation.

• Install an interrupt service routine for USB.

Details can be found in Target USB Driver on page 485.

Sample configurations for popular evaluation boards are supplied with the driver shipment.

They can be found in files called USB_Config_<TargetName>.c in the folders BSP/<Board-

Name>/Setup.

Add the appropriate configuration file to your project. If there is no configuration file for

your target hardware, take a file for a similar hardware and modify it if necessary.

If the file needs modifications, we recommend to copy it into the directory Config for easy

updates to later versions of emUSB-Device.

Add BSP file

Some targets require CPU specific functions for initialization, mainly for installing an inter-

rupt service routine. They are contained in the file BSP_USB.c. Sample BSP_USB.c files for

popular evaluation boards are supplied with the driver shipment. They can be found in the

folders BSP/<BoardName>/Setup.

Add the appropriate BSP_USB.c file to your project. If there is no BSP file for your target

hardware, take a file for a similar hardware and modify it if necessary.

If the file needs modifications, we recommend to copy it into the directory Config for easy

updates to later versions of emUSB-Device.

Note that a BSP_USB.c file is not always required, because for some target hardware all

runtime configuration is done in USB_X_Config.

3.1.5 Prepare and run the application

Choose a sample application from the folder Application and add it to your project. For

example, add USB_HID_Mouse.c as your application to your project. Compile and run the

application on the target hardware. After connecting the USB cable to the target device,

the mouse pointer should hop from left to right.

39 CHAPTER 3 How to setup your target system

40 CHAPTER 3 Updating emUSB-Device

3.2 Updating emUSB-Device

If an existing project should be updated to a later emUSB-Device version, only files have

to be replaced. You should have received the emUSB-Device update as a zip file. Unzip this

file to the location of your choice and replace all emUSB-Device files in your project with

the newer files from the emUSB-Device update shipment.

In general, all files from the following directories have to be updated:

•USB

•Inc

•SEGGER

•Doc

•Sample/USB/OS

Some files may contain modification required for project specific customization. These files

should reside in the folder Config and must not be overwritten. This includes:

•USB_Conf.h

•USB_ConfigIO.c

•BSP_USB.c

•USB_Config_<TargetName>.c

41 CHAPTER 3 emUSB-Device Configuration

3.3 emUSB-Device Configuration

An application using emUSB-Device must contain a structure containing the device identi-

fication information:

typedef struct {

U16 VendorId;

U16 ProductId;

char *sVendorName;

char *sProductName;

char *sSerialNumber

} USB_DEVICE_INFO;

Member Description

VendorId Vendor ID of the target.

ProductId Product ID of the target.

sVendorName The manufacturer name.

sProductName The product name of the target.

sSerialNumber The serial number of the device.

This structure and functions are included in every example application and can be used

without modifications in the development phase of your application, but you may not bring

a product on the market without modifying the Vendor ID and Product ID.

Ids Description

Default Vendor ID for all applications

0x8765 Example Vendor ID for all examples.

Used Product IDs

0x1240 Example Product ID for all bulk samples.

0x1234 Example Product ID for deprecated bulk samples

(using SEGGER Windows driver)

0x1000 Example Product ID for all MSD samples.

0x1200 Example Product ID for the MSD CD-ROM sample.

0x1111 Example Product ID for all CDC samples.

0x1112 Example Product ID for HID mouse sample.

0x1114 Example Product ID for the vendor specific HID

sample.

0x1115 Example Product ID for HID keyboard sample.

0x2114 Example Product ID for the Printer class sample.

0x3000 Example Product ID for RNDIS sample.

0x3003 Example Product ID for ECM sample.

42 CHAPTER 3 emUSB-Device Configuration

3.3.1 General emUSB-Device configuration

3.3.1.1 USB_DEVICE_INFO

Description

Device information that must be provided by the application via the function USBD_SetDe-

viceInfo() before the USB stack is started using USBD_Start() .

Prototype

typedef struct {

U16 VendorId;

U16 ProductId;

char *sVendorName;

char *sProductName;

char *sSerialNumber

} USB_DEVICE_INFO;

Additional information

The Product ID in combination with the Vendor ID creates a worldwide unique identifier for

the product model. The Vendor ID is assigned by the USB Implementers Forum (www.us-

b.org). For tests, the default number above (or pretty much any other number) can be

used. However, you may not bring a product to market without having been assigned your

own Vendor ID. For emUSB-Device-CDC: If you change this value, do not forget to make

the same change to the .inf file as described in section The .inf file on page 270. Other-

wise, the Windows host will be unable to locate the driver.

The manufacturer name, product name and serial number are used during the enumeration

phase. They together should give a detailed information about which device is connected

to the host.

Note

The max string length cannot be more than 126 ANSI characters.

Note for MSD: In order to confirm to the USB bootability specification, the minimum string

length of the serial number must be 12 characters where each character is a hexadecimal

digit (’0’ though ’9’ or ’A’ through ’F’).

Example

static const USB_DEVICE_INFO _DeviceInfo = {

0x8765, // VendorId

0x1234, // ProductId

"Vendor", // VendorName

"Bulk device", // ProductName

"13245678" // SerialNumber

}

...

USBD_SetDeviceInfo(&_DeviceInfo);

...

USBD_Start();

3.3.2 Additional required configuration functions for emUSB-

MSD

Refer to MSD Configuration on page 153 for more information about the required additional

configuration functions for emUSB-MSD.

43 CHAPTER 3 emUSB-Device Configuration

3.3.3 Descriptors

All configuration descriptors are automatically generated by emUSB-Device and do not

require configuration.

Chapter 4

USB Core

This chapter describes the basic functions of the USB Core.

45 CHAPTER 4 Overview

4.1 Overview

This chapter describes the functions of the core layer of emUSB-Device. These functions

are required for all USB class drivers and the unclassified bulk communication component.

General information

To communicate with the host, the example applications include a USB-specific header

USB.h. This file contains API functions to communicate with the USB host through the USB

Core driver.

Every application using USB Core must perform the following steps:

1. Initialize the USB stack. To initialize the USB stack USBD_Init() has to be

called. USBD_Init() performs the low-level initialization of the USB stack and calls

USBD_X_Config() to add a driver to the USB stack.

2. Add communication endpoints. You have to add the required endpoints with the

compatible transfer type for the desired interface before you can use any of the USB

class drivers or the unclassified bulk communication component. For the emUSB-Device

bulk component, refer to USB_BULK_INIT_DATA on page 96 for information about

the initialization structure that is required when you want to add a bulk interface. For

the emUSB-Device MSD component, refer to USB_MSD_INIT_DATA on page 171 and

USB_MSD_INST_DATA on page 173 for information about the initialization structures

that are required when you want to add an MSD interface. For the emUSB-Device

CDC component, refer to USB_CDC_INIT_DATA on page 298 for information about the

initialization structure that is required when you want to add a CDC interface. For

the emUSB-Device HID component, refer to USB_HID_INIT_DATA on page 325 for

information about the initialization structure that is required when you want to add a

HID interface.

3. Provide device information using USBD_SetDeviceInfo() .

4. Start the USB stack. Call USBD_Start() to start the USB stack.

Example applications for every supported USB class and the unclassified bulk component

are supplied. We recommend using one of these examples as a starting point for your own

application. All examples are supplied in the \Application\ directory.

46 CHAPTER 4 Target API

4.2 Target API

This section describes the functions that can be used by the target application.

Function Description

USB basic functions

USBD_Init() Initializes the USB device with its settings.

USBD_Start() Starts the emUSB-Device Core.

USBD_GetState() Returns the state of the USB device.

USBD_IsConfigured() Checks if the USB device is initialized and

ready.

USBD_Stop() Stops the USB communication.

USBD_DeInit() De-initialize the complete USB stack.

USB configuration functions

USBD_AddDriver() Adds a USB device driver to the USB stack.

USBD_SetISRMgmFuncs() Register interrupt management functions.

USBD_SetAttachFunc() Sets a function to perform hardware-spe-

cific actions to attach USB.

USBD_AddEP() Returns an endpoint “handle” that can be

used for the desired USB interface.

USBD_AddEPEx() Returns an endpoint “handle” that can be

used for the desired USB interface.

USBD_SetDeviceInfo() Sets a all information used during device

enumeration.

USBD_SetClassRequestHook() Sets a callback function that is called when

a setup class request is sent from the host

to the specified interface index.

USBD_SetVendorRequestHook() Sets a callback function that is called when

a setup vendor request is sent from the

host to the specified interface index.

USBD_SetIsSelfPowered() Sets whether the device is self-powered or

not.

USBD_SetMaxPower() Sets the maximum power consumption re-

ported to the host during enumeration.

USBD_SetOnEvent() Sets a callback function for an endpoint

that will be called on every RX or TX event

for that endpoint.

USBD_RemoveOnEvent() Removes a callback function which was

added via USBD_SetOnEvent from the call-

back list.

USBD_SetOnRxEP0() Sets a callback when data are received in

the data stage of the setup request.

USBD_SetOnSetupHook() Sets a callback function that is called when

any setup request is sent from the host for

the specified interface index.

USBD_WriteEP0FromISR() Write data to EP0 (control endpoint).

USBD_EnableIAD() Enables combination of multi-interface de-

vice classes with single-interface classes or

other multi-interface classes.

47 CHAPTER 4 Target API

Function Description

USBD_SetCacheConfig() Configures cache related functionality that

might be required by the stack for cache

handling in drivers.

USBD_RegisterSCHook() Sets a callback function that will be called

on every state change of the USB device.

USB I/O functions

USBD_Read() Reads data from the host.

USBD_ReadOverlapped() Reads data from the host asynchronously.

USBD_Receive() Reads data from host.

USBD_Write() Writes data to the host.

USBD_CancelIO() Cancel any read or write operation.

USBD_WaitForEndOfTransfer() Wait until the current transfer on a particu-

lar EP has completed.

USBD_WaitForTXReady() Waits (blocking) until the TX queue can ac-

cept another data packet.

USBD_GetNumBytesInBuffer() Returns the number of bytes that are

available in the internal BULK-OUT end-

point buffer.

USBD_GetNumBytesRemToRead() This function is to be used in combination

with USBD_ReadOverlapped().

USBD_GetNumBytesRemToWrite() This function is to be used in combination

with a non-blocking call to USBD_Write().

USBD_StallEP() Stalls an endpoint.

USB RemoteWakeUp functions

USBD_SetAllowRemoteWakeUp() Allows the device to publish that remote

wake is available.

USBD_DoRemoteWakeup() Performs a remote wakeup in order to

wake up the host from the standby/sus-

pend state.

Data structures

SEGGER_CACHE_CONFIG Used to pass cache configuration and call-

back function pointers to the stack.

48 CHAPTER 4 Target API

4.2.1 USB basic functions

4.2.1.1 USBD_GetState()

Description

Returns the state of the USB device.

Prototype

unsigned USBD_GetState(void);

Return value

A bitwise combination of the USB state flags:

USB_STAT_ATTACHED Device is attached. (Note 1)

USB_STAT_READY Device is ready.

USB_STAT_ADDRESSED Device is addressed.

USB_STAT_CONFIGURED Device is configured.

USB_STAT_SUSPENDED Device is suspended.

Additional information

A USB device has several possible states. Some of these states are visible to the USB

and the host, while others are internal to the USB device. Refer to Universal Serial Bus

Specification, Revision 2.0, Chapter 9 for detailed information.

Notes

(1) Attached in a USB sense of the word does not mean that the device is physically con-

nected to the PC via a USB cable, it only means that the pull-up resistor on the device side

is connected. The status can be “attached” regardless of whether the device is connected

to a host or not.

49 CHAPTER 4 Target API

4.2.1.2 USBD_Init()

Description

Initializes the USB device with its settings.

Prototype

void USBD_Init(void);

50 CHAPTER 4 Target API

4.2.1.3 USBD_IsConfigured()

Description

Checks if the USB device is initialized and ready.

Prototype

char USBD_IsConfigured(void);

Return value

0 USB device is not configured.

1 USB device is configured.

51 CHAPTER 4 Target API

4.2.1.4 USBD_Start()

Description

Starts the emUSB-Device Core.

Prototype

void USBD_Start(void);

Additional information

This function should be called after configuring USB Core. It initiates a hardware attach and

updates the endpoint configuration. When the USB cable is connected to the device, the

host will start enumeration of the device.

52 CHAPTER 4 Target API

4.2.1.5 USBD_Stop()

Description

Stops the USB communication. This also makes sure that the device is detached from the

HOST.

Prototype

void USBD_Stop(void);

53 CHAPTER 4 Target API

4.2.1.6 USBD_DeInit()

Description

De-initialize the complete USB stack.

Prototype

void USBD_DeInit(void);

Additional information

This function also calls USBD_Stop() internally.

54 CHAPTER 4 Target API

4.2.2 USB configuration functions

4.2.2.1 USBD_AddDriver()

Description

Adds a USB device driver to the USB stack. This function should be called from within

USBD_X_Config() which is implemented in USB_Config_*.c.

Prototype

void USBD_AddDriver(const USB_HW_DRIVER * pDriver);

Parameters

Parameter Description

pDriver Pointer to the driver API structure.

Additional information

To add the driver, use USBD_AddDriver() with the identifier of the compatible driver. Refer

to the section “Available target USB drivers” in the USB.h header file for a list of supported

devices and their valid identifiers.

Example

/*********************************************************************

* USBD_X_Config

void USBD_X_Config(void) {

BSP_USB_Init();

USB_DRIVER_LPC17xx_ConfigAddr(0x2008C000); // USB controller of LPC1788

// is located @ 0x2008C000

USBD_AddDriver(&USB_Driver_NXPLPC17xx);

USBD_SetISRMgmFuncs(_EnableISR, NULL, NULL);

}

55 CHAPTER 4 Target API

4.2.2.2 USBD_SetISRMgmFuncs()

Description

Prototype

void USBD_SetISRMgmFuncs(USB_ENABLE_ISR_FUNC * pfEnableISR,

USB_INC_DI_FUNC * pfIncDI,

USB_DEC_RI_FUNC * pfDecRI);

Parameters

Parameter Description

pfEnableISR Pointer to the function to install the interrupt handler and

enable the USB interrupt.

pfIncDI Unused.

pfDecRI Unused.

Additional information

This function must be called within USBD_X_Config() function. See Adding a driver to

emUSB-Device on page 487. The functions pointer prototype is defined as follows:

typedef void USB_ENABLE_ISR_FUNC (USB_ISR_HANDLER * pfISRHandler);

Example

See USBD_AddDriver().

56 CHAPTER 4 Target API

4.2.2.3 USBD_SetAttachFunc()

Description

Sets a function to perform hardware-specific actions to attach USB.

Prototype

void USBD_SetAttachFunc(USB_ATTACH_FUNC * pfAttach);

Parameters

Parameter Description

pfAttach Pointer to the attach function.

Additional information

This function must be called within USBD_X_Config() function. See Adding a driver to

emUSB-Device on page 487. The functions pointer prototypes are defined as follows:

typedef void USB_ATTACH_FUNC (void);

Example

See USBD_X_Config() on page 487.

57 CHAPTER 4 Target API

4.2.2.4 USBD_AddEP()

Description

Returns an endpoint “handle” that can be used for the desired USB interface.

Prototype

unsigned USBD_AddEP(U8 InDir,

U8 TransferType,

U16 Interval,

U8 * pBuffer,

unsigned BufferSize);

Parameters

Parameter Description

InDir Specifies the direction of the desired endpoint.

•USB_DIR_IN

•USB_DIR_OUT

TransferType

Specifies the transfer type of the endpoint. The following val-

ues are allowed:

•USB_TRANSFER_TYPE_BULK

•USB_TRANSFER_TYPE_ISO

•USB_TRANSFER_TYPE_INT

Interval Specifies the interval measured in units of 125us (micro

frames). This value should be zero for a bulk endpoint.

pBuffer Pointer to a buffer that is used for OUT-transactions. For IN-

endpoints this parameter must be NULL.

BufferSize Size of the buffer (OUT endpoints only). Must be a multiple

of the maximum packet size.

Return value

> 0 A valid endpoint handle is returned.

= 0 Error.

Additional information

The Interval parameter specifies the frequency in which the endpoint should be polled for

information by the host. It must be specified in units of 125 us.

Depending on the actual speed of the device during enumeration, the USB stack converts

the interval to the correct value required for the endpoint descriptor according to the USB

specification (into milliseconds for low/full speed, into 125 us for high speed).

For endpoints of type USB_TRANSFER_TYPE_BULK the value is ignored and should be set to 0.

58 CHAPTER 4 Target API

4.2.2.5 USBD_AddEPEx()

Description

Returns an endpoint “handle” that can be used for the desired USB interface.

Prototype

unsigned USBD_AddEPEx(const USB_ADD_EP_INFO * pInfo,

U8 * pBuffer,

unsigned BufferSize);

Parameters

Parameter Description

pInfo Pointer to a structure of type USB_ADD_EP_INFO.

pBuffer Pointer to a buffer that is used for OUT-transactions. For IN-

endpoints this parameter must be NULL.

BufferSize Size of the buffer (OUT endpoints only). Must be a multiple

of the maximum packet size.

Return value

> 0 A valid endpoint handle is returned.

= 0 Error.

59 CHAPTER 4 Target API

4.2.2.6 USBD_SetDeviceInfo()

Description

Sets a all information used during device enumeration.

Prototype

void USBD_SetDeviceInfo(const USB_DEVICE_INFO * pDeviceInfo);

Parameters

Parameter Description

pDeviceInfo Pointer to a structure containing the device information.

Must point to static data that is not changed while the stack

is running.

Additional information

See USB_DEVICE_INFO on page 42 for a description of the structure.

Example

See USB_DEVICE_INFO on page 42.

60 CHAPTER 4 Target API

4.2.2.7 USBD_SetClassRequestHook()

Description

Sets a callback function that is called when a setup class request is sent from the host to

the specified interface index.

Prototype

void USBD_SetClassRequestHook(unsigned InterfaceNum,

USB_ON_CLASS_REQUEST * pfOnClassRequest);

Parameters

Parameter Description

InterfaceNum Interface index that for setting the class request callback.

pfOnClassRequest Pointer to the callback.

Additional information

Note that the callback will be called within an ISR, therefore it should never block. If it

is necessary to send data from the callback function through endpoint 0, use the function

USBD_WriteEP0FromISR().

USB_ON_CLASS_REQUEST is defined as follows:

typedef void USB_ON_CLASS_REQUEST(const USB_SETUP_PACKET * pSetupPacket);

61 CHAPTER 4 Target API

4.2.2.8 USBD_SetVendorRequestHook()

Description

Sets a callback function that is called when a setup vendor request is sent from the host

to the specified interface index.

Prototype

void USBD_SetVendorRequestHook(unsigned InterfaceNum,

USB_ON_CLASS_REQUEST * pfOnVendorRequest);

Parameters

Parameter Description

InterfaceNum Interface index that for setting the class request callback.

pfOnVendorRequest Pointer to the callback.

Additional information

Note that the callback will be called within an ISR, therefore it should never block. If it

is necessary to send data from the callback function through endpoint 0, use the function

USBD_WriteEP0FromISR().

USB_ON_CLASS_REQUEST is defined as follows:

typedef void USB_ON_CLASS_REQUEST(const USB_SETUP_PACKET * pSetupPacket);

62 CHAPTER 4 Target API

4.2.2.9 USBD_SetIsSelfPowered()

Description

Sets whether the device is self-powered or not.

Prototype

void USBD_SetIsSelfPowered(U8 IsSelfPowered);

Parameters

Parameter Description

IsSelfPowered • 0 - Device is not self-powered.

• 1 - Device is self-powered.

Additional information

This function has to be called before USBD_Start(), as it will specify if the device is self-

powered or not. The default value is 0 (not self-powered).

63 CHAPTER 4 Target API

4.2.2.10 USBD_SetMaxPower()

Description

Sets the maximum power consumption reported to the host during enumeration.

Prototype

void USBD_SetMaxPower(unsigned MaxPower);

Parameters

Parameter Description

MaxPower Current consumption of the device given in mA. MaxPower

shall be in range between 0mA - 500mA.

Additional information

This function shall be called before USBD_Start(), as it will specify how much power the

device will consume from the host. If this function is not called, a default value of 100 mA

will be used.

64 CHAPTER 4 Target API

4.2.2.11 USBD_SetOnEvent()

Description

Sets a callback function for an endpoint that will be called on every RX or TX event for

that endpoint.

Prototype

void USBD_SetOnEvent(unsigned EPIndex,

USB_EVENT_CALLBACK * pEventCb,

USB_EVENT_CALLBACK_FUNC * pfEventCb,

void * pContext);

Parameters

Parameter Description

EPIndex Endpoint index returned by USBD_AddEP().

pEventCb Pointer to a USB_EVENT_CALLBACK structure (will be initial-

ized by this function).

pfEventCb Pointer to the callback routine that will be called on every

event on the USB endpoint.

pContext A pointer which is used as parameter for the callback func-

tion.

Additional information

The USB_EVENT_CALLBACK structure is private to the USB stack. It will be initialized by

USBD_SetOnEvent(). The USB stack keeps track of all event callback functions using a

linked list. The USB_EVENT_CALLBACK structure will be included into this linked list and must

reside in static memory.

The callback function is called only, if a read or write operation was started for the endpoint

using one of the USBD_Read…() or USBD_Write…() functions.

Additional information

The callback function has the following prototype:

typedef void USB_EVENT_CALLBACK_FUNC(unsigned Events, void *pContext);

Parameter Description

Events A bit mask indicating which events occurred on the

endpoint.

pContext The pointer which was provided to the USBD_SetOn-

Event() function.

Note that the callback function will be called within an ISR, therefore it should never block.

The first parameter to the callback function will contain a bit mask for all events that trig-

gered the call:

Event Description

USB_EVENT_DATA_READ Some data was received from the host on the end-

point.

USB_EVENT_DATA_SEND Some data was send to the host, so that (part of)

the user write buffer may be reused by the applica-

tion.

USB_EVENT_DATA_ACKED Some data was acknowledged by the host.

USB_EVENT_READ_COMPLETE The last read operation was completed.

65 CHAPTER 4 Target API

Event Description

USB_EVENT_READ_ABORT A read transfer was aborted.

USB_EVENT_WRITE_ABORT A write transfer was aborted.

USB_EVENT_WRITE_COMPLETE All write operations were completed.

Example

// The callback function.

static void _OnEvent(unsigned Events, void *pContext) {

if ((Events & USB_EVENT_DATA_SEND) != 0 &&

// Check for last write transfer to be completed.

USBD_GetNumBytesToWrite(_hInst) == 0) {

<.. prepare next data for writing..>

// Send next packet of data.

r = USBD_Write(EPIndex, &ac[0], 200, 0, -1);

if (r < 0) {

<.. error handling..>

}

// Main programm.

// Register callback function.

static USB_EVENT_CALLBACK _usb_callback;

USBD_SetOnEvent(EPIndex, &_usb_callback, _OnEvent, NULL);

// Send the first packet of data using an asynchronous write operation.

r = USBD_Write(EPIndex, &ac[0], 200, 0, -1);

if (r < 0) {

<.. error handling..>

}

<.. do anything else here while the whole data is send..>

66 CHAPTER 4 Target API

4.2.2.12 USBD_RemoveOnEvent()

Description

Removes a callback function which was added via USBD_SetOnEvent from the callback list.

Prototype

void USBD_RemoveOnEvent( unsigned EPIndex,

const USB_EVENT_CALLBACK * pEventCb);

Parameters

Parameter Description

EPIndex Endpoint index returned by USBD_AddEP().

pEventCb Pointer to a USB_EVENT_CALLBACK structure which was used

with USBD_SetOnEvent.

67 CHAPTER 4 Target API

4.2.2.13 USBD_SetOnRxEP0()

Description

Sets a callback when data are received in the data stage of the setup request.

Prototype

void USBD_SetOnRxEP0(USB_ON_RX_FUNC * pfOnRx);

Parameters

Parameter Description

pfOnRx Pointer to a function that should be called when receiving

data other than setup packets on EP0.

Additional information

Please note that this function can be called multiple times from different classes in order

to check the data.

Note that the callback will be called within an ISR, therefore it should never block. If it

is necessary to send data from the callback function through endpoint 0, use the function

USBD_WriteEP0FromISR().

USB_ON_RX_FUNC is defined as follows:

typedef void USB_ON_RX_FUNC(const U8 * pData, unsigned NumBytes);

68 CHAPTER 4 Target API

4.2.2.14 USBD_SetOnSetupHook()

Description

Sets a callback function that is called when any setup request is sent from the host for the

specified interface index.

Prototype

void USBD_SetOnSetupHook(unsigned InterfaceNum,

USB_ON_SETUP * pfOnSetup);

Parameters

Parameter Description

InterfaceNum Interface index that for setting the setup request callback.

pfOnSetup Pointer to the callback.

Additional information

Note that the callback will be called within an ISR, therefore it should never block. If it

is necessary to send data from the callback function through endpoint 0, use the function

USBD_WriteEP0FromISR().

USB_ON_SETUP is defined as follows:

typedef int USB_ON_SETUP(const USB_SETUP_PACKET * pSetupPacket);

69 CHAPTER 4 Target API

4.2.2.15 USBD_WriteEP0FromISR()

Description

Write data to EP0 (control endpoint). This function may be called in an interrupt context.

Prototype

void USBD_WriteEP0FromISR(const void * pData,

unsigned NumBytes,

char Send0PacketIfRequired);

Parameters

Parameter Description

pData Data that should be written.

NumBytes Number of bytes to write.

Send0PacketIfRequired

Specifies that a zero-length packet should be sent when

the last data packet to the host is a multiple of MaxPack-

etSize. Normally MaxPacketSize for control mode transfer is

64 byte.

70 CHAPTER 4 Target API

4.2.2.16 USBD_EnableIAD()

Description

Enables combination of multi-interface device classes with single-interface classes or other

multi-interface classes.

Prototype

void USBD_EnableIAD(void);

Additional information

Simple device classes such as HID and MSD or BULK use only one interface descriptor to

describe the class. The interface descriptor also contains the device class code. The CDC

device class uses more than one interface descriptor to describe the class. The device class

code will then be written into the device descriptor. It may be possible to add an interface

which does not belong to the CDC class, but it may not be correctly recognized by the host,

this is not standardized and depends on the host. In order to allow this, a new descriptor

type was introduced:

IAD (Interface Association Descriptor), this descriptor will encapsulate the multi-interface

class into this IA descriptor, so that it will be seen as one single interface and will then

allow to add other device classes.

If you intend to use the CDC component with any other component, please call USBD_En-

ableIAD() before adding the CDC component through USBD_CDC_Add().

71 CHAPTER 4 Target API

4.2.2.17 USBD_SetCacheConfig()

Description

Configures cache related functionality that might be required by the stack for cache handling

in drivers.

Prototype

void USBD_SetCacheConfig(const SEGGER_CACHE_CONFIG * pConfig,

unsigned ConfSize);

Parameters

Parameter Description

pConfig Pointer to an element of SEGGER_CACHE_CONFIG .

ConfSize Size of the passed structure in case library and header size

of the structure differs.

Additional information

This function has to called in USBD_X_Config(). This function replaces the legacy cache

functions BSP_CACHE_CleanRange and BSP_CACHE_InvalidateRange. If you still want to

use these routines please set USBD_USE_LEGACY_CACHE_ROUTINES to 1 in your USB_Conf.h

file.

72 CHAPTER 4 Target API

4.2.2.18 USBD_RegisterSCHook()

Description

Sets a callback function that will be called on every state change of the USB device.

Prototype

int USBD_RegisterSCHook(USB_HOOK * pHook,

USB_STATE_CALLBACK_FUNC * pfStateCb,

void * pContext);

Parameters

Parameter Description

pHook Pointer to a USB_HOOK structure (will be initialized by this

function).

pfStateCb Pointer to the callback routine that will be called on every

state change.

pContext A pointer which is used as parameter for the callback func-

tion.

Return value

0 OK.

1 Error, specified hook already exists.

Additional information

The USB_HOOK structure is private to the USB stack. It will be initialized by USBD_Regis-

terSCHook(). The USB stack keeps track of all state change callback functions using a

linked list. The USB_HOOK structure will be included into this linked list and must reside in

static memory.

Note that the callback function will be called within an ISR, therefore it should never block.

Example

// The callback function.

static void _OnStateChange(void *pContext, U8 NewState) {

if ((NewState & (USB_STAT_CONFIGURED | USB_STAT_SUSPENDED)) == USB_STAT_CONFIGURED) {

// Device is enumerated

} else {

// Device not enumerated

}

// Main programm.

static USB_HOOK Hook;

USBD_Init();

...

USBD_RegisterSCHook(&Hook, _OnStateChange, NULL);

...

USBD_Start();

73 CHAPTER 4 Target API

4.2.3 USB I/O functions

4.2.3.1 USBD_Read()

Description

Reads data from the host.

Prototype

int USBD_Read(unsigned EPOut,

void * pData,

unsigned NumBytesReq,

unsigned Timeout);

Parameters

Parameter Description

EPOut Handle to an OUT endpoint returned by USBD_AddEP().

pData Pointer to a buffer where the received data will be stored.

NumBytes Number of bytes to read.

Timeout Timeout given in milliseconds. A zero value results in an infi-

nite timeout.

Return value

= NumBytes Requested data was successfully read within the given timeout.

≥ 0 && < NumBytes Timeout has occurred (Number of bytes read before timeout).

< 0 An error occurred.

Additional information

This function blocks the task until all data has been read or a timeout occurs. In case of a

reset or a disconnect USB_STATUS_ERROR is returned.

If the USB stack receives a data packet from the host containing more bytes than requested,

the remaining bytes are stored into the internal buffer of the endpoint, that was provided

via the USBD_AddEP() function. This data can be retrieved by a later call to USBD_Receive()

or USBD_Read(). See also USBD_GetNumBytesInBuffer().

74 CHAPTER 4 Target API

4.2.3.2 USBD_ReadOverlapped()

Description

Reads data from the host asynchronously.

Prototype

int USBD_ReadOverlapped(unsigned EPOut,

void * pData,

unsigned NumBytesReq);

Parameters

Parameter Description

EPOut Handle to an OUT endpoint returned by USBD_AddEP().

pData Pointer to a buffer where the received data will be stored.

NumBytes Number of bytes to read.

Return value

≥ 0 Number of bytes that have been read from the internal buffer (success).

= 0 No data was found in the internal buffer (success).

< 0 An error occurred.

Additional information

This function will not block the calling task. The read transfer will be initiated and the func-

tion returns immediately. In order to synchronize, USBD_WaitForEndOfTransfer() needs

to be called.

Another synchronization method would be to periodically call USBD_GetNumBytesRemToRe-

ad() in order to see how many bytes still need to be received (this method is preferred

when a non-blocking solution is necessary).

The read operation can be canceled using USBD_CancelIO().

The buffer pointed to by pData must be valid until the read operation is terminated.

75 CHAPTER 4 Target API

4.2.3.3 USBD_Receive()

Description

Reads data from host. The function blocks until any data have been received. In contrast

to USBD_Read() this function does not wait for all of NumBytes to be received, but returns

after the first packet has been received or after the timeout occurs.

Prototype

int USBD_Receive(unsigned EPOut,

void * pData,

unsigned NumBytesReq,

int Timeout);

Parameters

Parameter Description

EPOut Handle to an OUT endpoint returned by USBD_AddEP().

pData Pointer to a buffer where the received data will be stored.

NumBytes Number of bytes to read.

Timeout Timeout given in milliseconds. A zero value results in an infi-

nite timeout. If Timeout is -1, the function never blocks.

Return value

> 0 Number of bytes that have been read within the given timeout.

= 0 A timeout occurred (if Timeout > 0), zero packet received (not every controller

supports this!), no data in buffer (if Timeout < 0) or the target was disconnect-

ed during the function call and no data was read so far.

< 0 An error occurred.

Additional information

If no error occurs, this function returns the number of bytes received. Calling USBD_Re-

ceive() will return as much data as is currently available up to the size of the buffer spec-

ified within the specified timeout. This function also returns when the target is disconnected

from the host or when a USB reset occurred during the function call, it will then return the

number of bytes read so far. If the target was disconnected before this function was called,

it returns USB_STATUS_ERROR.

If the USB stack receives a data packet from the host containing more bytes than requested,

the remaining bytes are stored into the internal buffer of the endpoint, that was provided via

USBD_AddEP(). This data can be retrieved by a later call to USBD_Receive() / USBD_Read().

See also USBD_GetNumBytesInBuffer().

A call of USBD_Receive(EPOut, NULL, 0, -1) can be used to trigger an asynchronous read

that stores the data into the internal buffer.

76 CHAPTER 4 Target API

4.2.3.4 USBD_Write()

Description

Writes data to the host. Depending on the Timeout parameter, the function may block until

NumBytes have been written or a timeout occurs.

Prototype

int USBD_Write( unsigned EPIndex,

const void * pData,

unsigned NumBytes,

char Send0PacketIfRequired,

int ms);

Parameters

Parameter Description

EPIndex Handle to an IN endpoint returned by USBD_AddEP().

pData Pointer to data that should be sent to the host.

NumBytes Number of bytes to be written.

Send0PacketIfRequired Specifies that a zero-length packet should be sent when the

last data packet to the host is a multiple of MaxPacketSize.

Timeout Timeout in milliseconds. 0 means infinite. If Timeout is

-1, the function returns immediately and the transfer is

processed asynchronously.

Return value

= 0 Successful started an asynchronous write transfer or a timeout

has occurred and no data was written.

> 0 && < NumBytes Number of bytes that have been written before a timeout oc-

curred.

= NumBytes Write transfer successful completed.

< 0 An error occurred.

Additional information

This function also returns when the target is disconnected from host or when a USB reset

occurred.

The USB stack is able to queue a small number of asynchronous write transfers (Timeout

= -1). If a write transfer is still in progress when this function is called and the USB stack

can not accept another write transfer request, the functions returns USB_STATUS_EP_BUSY.

A synchronous write transfer (Timeout ≥ 0) will always block until the transfer (including

all pending transfers) are finished.

In order to synchronize, USBD_WaitForEndOfTransfer() needs to be called. Another syn-

chronization method would be to periodically call USBD_GetNumBytesRemToWrite() in or-

der to see how many bytes still need to be written (this method is preferred when a non-

blocking solution is necessary).

The write operation can be canceled using USBD_CancelIO().

If pData = NULL and NumBytes = 0, a zero-length packet is sent to the host.

The content of the buffer pointed to by pData must not be changed until the transfer has

been completed.

77 CHAPTER 4 Target API

4.2.3.5 USBD_CancelIO()

Description

Cancel any read or write operation.

Prototype

void USBD_CancelIO(unsigned EPIndex);

Parameters

Parameter Description

EPIndex Handle to an endpoint returned by USBD_AddEP().

78 CHAPTER 4 Target API

4.2.3.6 USBD_WaitForEndOfTransfer()

Description

Wait until the current transfer on a particular EP has completed. This function must be

called from a task.

Prototype

int USBD_WaitForEndOfTransfer(unsigned EPIndex,

unsigned Timeout);

Parameters

Parameter Description

EPIndex Handle to the endpoint returned by USBD_AddEP().

Timeout Timeout in milliseconds, 0 means infinite wait.

Return value

0 Transfer completed.

1Timeout occurred.

Additional information

In case of a timeout, a current transfer is canceled.

79 CHAPTER 4 Target API

4.2.3.7 USBD_WaitForTXReady()

Description

Waits (blocking) until the TX queue can accept another data packet. This function is used

in combination with a non-blocking call to USBD_Write(), it waits until a new asynchronous

write data transfer will be accepted by the USB stack.

Prototype

int USBD_WaitForTXReady(unsigned EPIndex,

int Timeout);

Parameters

Parameter Description

EPIndex Handle to an IN endpoint returned by USBD_AddEP().

Timeout Timeout in milliseconds. 0 means infinite. If Timeout is neg-

ative, the function will return immediately.

Return value

= 0 A new asynchronous write data transfer will be accepted.

= 1 The write queue is full, a call to USBD_Write() would return USB_S-

TATUS_EP_BUSY.

< 0 Error occurred.

Additional information

If Timeout is 0, the function never returns 1.

If Timeout is -1, the function will not wait, but immediately return the current state.

80 CHAPTER 4 Target API

4.2.3.8 USBD_GetNumBytesInBuffer()

Description

Returns the number of bytes that are available in the internal BULK-OUT endpoint buffer.

Prototype

unsigned USBD_GetNumBytesInBuffer(unsigned EPIndex);

Parameters

Parameter Description

EPIndex Handle to an OUT endpoint returned by USBD_AddEP().

Return value

Number of bytes which have been stored in the internal buffer.

Additional information

The number of bytes returned by this function can be read using USBD_Read() or USBD_Re-

ceive() without blocking.

81 CHAPTER 4 Target API

4.2.3.9 USBD_GetNumBytesRemToRead()

Description

This function is to be used in combination with USBD_ReadOverlapped(). It returns the

number of bytes which still have to be read during the transaction.

Prototype

unsigned USBD_GetNumBytesRemToRead(unsigned EPIndex);

Parameters

Parameter Description

EPIndex Handle to an OUT endpoint returned by USBD_AddEP().

Return value

Number of bytes which still have to be read.

Additional information

Note that this function does not return the number of bytes that have been read, but the

number of bytes which still have to be read. This function does not block.

82 CHAPTER 4 Target API

4.2.3.10 USBD_GetNumBytesRemToWrite()

Description

This function is to be used in combination with a non-blocking call to USBD_Write(). It

returns the number of bytes which still have to be written during the transaction.

Prototype

unsigned USBD_GetNumBytesRemToWrite(unsigned EPIndex);

Parameters

Parameter Description

EPIndex Handle to an IN endpoint returned by USBD_AddEP().

Return value

Number of bytes which still have to be written.

Additional information

Note that this function does not return the number of bytes that have been written, but the

number of bytes which still have to be written. This function does not block.

83 CHAPTER 4 Target API

4.2.3.11 USBD_StallEP()

Description

Stalls an endpoint.

Prototype

void USBD_StallEP(unsigned EPIndex);

Parameters

Parameter Description

EPIndex Handle to the endpoint handle returned by USBD_AddEP().

84 CHAPTER 4 Target API

4.2.4 USB Remote wakeup functions

Remote wakeup is a feature that allows a device to wake a host system from a USB suspend

state.

In order to do this a special resume signal is sent over the USB data lines.

Additionally the USB host controller and operating system has to be able to handle this

signaling.

Windows OS

Currently Windows OS only supports the wakeup feature on devices based on HID mouse/

keyboard, CDC Modem and RNDIS Ethernet class. Remote wakeup for MSD, generic bulk

and CDC serial is not supported by Windows. So therefore a HID mouse class even as

dummy interface within your USB configuration is currently mandatory.

Windows must also be told that the device shall wake the PC from the suspend state. This

is done by setting the option “Allow this device to bring the computer out of standby”.

macOS

macOS supports remote wakeup for all device classes.

85 CHAPTER 4 Target API

4.2.4.1 USBD_SetAllowRemoteWakeUp()

Description

Allows the device to publish that remote wake is available.

Prototype

void USBD_SetAllowRemoteWakeUp(U8 AllowRemoteWakeup);

Parameters

Parameter Description

AllowRemoteWakeup • 1 - Allows and publishes that remote wakeup is available.

• 0 - Publish that remote wakeup is not available.

Additional information

This function must be called before the function USBD_Start() is called. This ensures that

the Host is informed that USB remote wake up is available.

86 CHAPTER 4 Target API

4.2.5 Data structures

4.2.5.1 USB_ADD_EP_INFO

Description

Structure used by USBD_AddEPEx() when adding an endpoint.

Type definition

typedef struct {

U8 Flags;

U8 InDir;

U8 TransferType;

U16 Interval;

unsigned MaxPacketSize;

} USB_ADD_EP_INFO;

Structure members

Member Description

Flags Reserved. Must be zero.

InDir Specifies the direction of the desired endpoint.

•USB_DIR_IN

•USB_DIR_OUT

TransferType

Specifies the transfer type of the endpoint. The following val-

ues are allowed:

•USB_TRANSFER_TYPE_BULK

•USB_TRANSFER_TYPE_ISO

•USB_TRANSFER_TYPE_INT

Interval Specifies the interval measured in units of 125us (mi-

croframes). This value should be zero for a bulk endpoint.

MaxPacketSize Maximum packet size for the endpoint.

Additional information

The Interval parameter specifies the frequency in which the endpoint should be polled for

information by the host. It must be specified in units of 125 us.

Depending on the actual speed of the device during enumeration, the USB stack converts

the interval to the correct value required for the endpoint descriptor according to the USB

specification (into milliseconds for low/full speed, into 125 us for high speed).

For endpoints of type USB_TRANSFER_TYPE_BULK the value is ignored and should be set to 0.

87 CHAPTER 4 Target API

4.2.5.2 SEGGER_CACHE_CONFIG

Description

Used to pass cache configuration and callback function pointers to the stack.

Prototype

typedef struct {

int CacheLineSize;

void (*pfDMB) (void);

void (*pfClean) (void *p, unsigned NumBytes);

void (*pfInvalidate)(void *p, unsigned NumBytes);

} SEGGER_CACHE_CONFIG;

Member Description

CacheLineSize

Length of one cache line of the CPU.

= 0: No Cache.

> 0: Cache line size in bytes.

Most Systems such as ARM9 use a 32 bytes cache line size.

pfDMB Pointer to a callback function that executes a DMB (Data Memory Bar-

rier) instruction to make sure all memory operations are completed.

Can be NULL.

pfClean Pointer to a callback function that executes a clean operation on

cached memory. Can be NULL.

pfInvalidate Pointer to a callback function that executes an invalidate operation on

cached memory. Can be NULL.

Additional information

For further information about how this structure is used please refer to USBD_SetCacheCon-

fig on page 71.

Chapter 5

Bulk communication

This chapter describes how to get emUSB-Device-Bulk up and running.

89 CHAPTER 5 Generic bulk stack

5.1 Generic bulk stack

The generic bulk stack is located in the directory USB. All C files in the directory should be

included in the project (compiled and linked as part of your project). The files in this direc-

tory are maintained by SEGGER and should not require any modification. All files requiring

modifications have been placed in other directories.

90 CHAPTER 5 Requirements for the Host (PC)

5.2 Requirements for the Host (PC)

In order to communicate with a target (client) running emUSB-Device, the operating system

running on the host must recognize the device connected to it.

5.2.1 Windows

Microsoft’s Windows operating systems (Starting with XP Service Pack 2) contains a generic

driver called WinUSB.sys that is used to handle all communication to a emUSB-Device

running a BULK interface. If a emUSB bulk device is connected to a Windows 8, 8.1 and

10 PC for the first time, Windows will install the WinUSB driver automatically. For Windows

versions less than Windows 8. Windows provides a driver for Windows Vista and Windows

7 but this needs to be installed manually. A driver installation tool including the mentioned

driver is available in the Windows\USB\Bulk\WinUSBInstall. Windows XP user can use

the driver package located under Windows\USB\Bulk\WinUSB_USBBulk_XP. In order to get

emUSB BULK running with the WinUSB driver the following must be considered:

• The function USBD_BULK_SetMSDescInfo() must be called in the target application.

• The Product IDs 1234 and 1121 must not be used.

5.2.2 Linux

Linux can handle emUSB BULK devices out of the box.

By default a USB device can only be accessed by a process that is running with “root”

rights. In order to use the USB bulk device from normal user programs an udev rule has to

be configured for the device (refer to the linux udev documentation). The emUSB-Device

release contains a sample configuration file 99-emUSBD.rules, which may be modified and

copied to /etc/udev/rules.d on the host machine.

5.2.3 macOS

macOS can handle emUSB BULK devices out of the box.

91 CHAPTER 5 Example application

5.3 Example application

Example applications for both the target (client) and the PC (host) are supplied. These

can be used for testing the correct installation and proper function of the device running

emUSB-Device.

The host sample applications can be used for Windows, Linux and MacOSX. Precompiled

executables for Windows can be found in the subfolder Windows/USB/Bulk/WindowsAppli-

cation/Exe.

For example: The application USB_BULK_Echo1.c is a modified echo server; the application

receives data byte by byte, increments every single byte and sends it back to the host.

To use this application, make sure to use the corresponding example files both on the host-

side as on the target side. The example applications on the PC host are named in the

same way, just without the prefix USB_BULK_ , for example, if the host runs Echo1.exe,

USB_BULK_Echo1.c has to be included into your project, compiled and downloaded into

your target. There are additional examples that can be used for testing emUSB-Device.

The following start application files are provided:

File Description

USB_BULK_Echo1.c This application was described in the upper text.

USB_BULK_EchoFast.c This is the faster version of USB_BULK_Echo1.c.

USB_BULK_Test.c This application can be used to test emUSB-Device-Bulk

with different packet sizes received from and sent to the

PC host.

USB_BULK_Performance.c Measures BULK data throughput.

The example applications for the target-side are supplied in source code in the Application

directory.

Depending on which application is running on the emUSB-Device device, use one of the

following example applications:

92 CHAPTER 5 Example application

File Description

Echo1.exe If the USB_BULK_Echo1.c sample application is running on

the emUSB-Device-Bulk device, use this application.

EchoFast.exe If the USB_BULK_EchoFast.c sample application is running

on the emUSB-Device-Bulk device, use this application.

Test.exe If the USB_BULK_Test.c application is running on the

emUSB-Device-Bulk device, use this application to test the

emUSB-Device-Bulk stack.

Performance.exe If the USB_BULK_Performace.c application is running on the

emUSB-Device-Bulk device, use this application to measures

BULK data throughput.

For information how to compile the host examples (especially for Linux and MacOSX) refer

to Compiling the PC example application on page 93.

The start application will of course later on be replaced by the real application program.

For the purpose of getting emUSB-Device up and running as well as doing an initial test,

the start application should not be modified.

5.3.1 Running the example applications

To test the emUSB-Device-Bulk component, build and download the application of choice

for the target-side.

To run one of the example applications, simply start the executable, for example by double

clicking it.

If a connection can be established, it exchanges data with the target, testing the USB

connection.

Example output of Echo1.exe:

If the host example application can communicate with the emUSB-Device device, the ex-

ample application will be in interactive mode for the Echo1 and the EchoFast application.

In case of an error, a message box is displayed.

Error Messages Description

Unable to connect to

USB BULK device The USB device is not connected to the PC or the connection

is faulty.

Could not write to

device The PC sample application was not able to write.

93 CHAPTER 5 Example application

Error Messages Description

Could not read from

device (time-out) The PC sample application was not able to read.

Wrong data read The result of the target sample application is not correct.

5.3.2 Compiling the PC example application

5.3.2.1 Windows

For compiling the example application you need Visual C++ 2010 (or later).

The source code of the sample application is located in the subfolder Windows\USB\Bulk

\WindowsApplication. Open the file USBBULK_Start.sln and compile the source.

5.3.2.2 Linux

The subfolder Windows\USB\Bulk\WindowsApplication contains a Makefile for Linux.

Change to this folder and execute “make”.

5.3.2.3 macOS

The subfolder Windows\USB\Bulk\WindowsApplication contains a Makefile for macOS.

Change to this folder and execute “make -f Makefile_MacOSX”.

94 CHAPTER 5 Target API

5.4 Target API

This chapter describes the functions that can be used with the target system.

General information

To communicate with the host, the sample application project includes USB-specific header

and source files (USB.h, USB_Main.c, USB_Setup.c, USB_Bulk.c, USB_Bulk.h). These files

contain API functions to communicate with the USB host through the emUSB-Device driver.

Purpose of the USB Device API functions

To have an easy start up when writing an application on the device side, these API functions

have a simple interface and handle all operations that need to be done to communicate

with the hosts kernel.

Therefore, all operations that need to write to or read from the emUSB-Device are handled

internally by the provided API functions.

5.4.1 Target interface function list

Routine Explanation

USB-Bulk functions

USBD_BULK_Add() Adds interface for USB-Bulk communica-

tion to emUSB-Device.

USBD_BULK_Add_Ex() Adds interface for USB-Bulk communica-

tion to emUSB-Device.

USBD_BULK_SetMSDescInfo() Enables use of Microsoft OS Descriptors.

USBD_BULK_CancelRead() Cancels any non-blocking/blocking read

operation that is pending.

USBD_BULK_CancelWrite() Cancels any non-blocking/blocking write

operation that is pending.

USBD_BULK_GetNumBytesInBuffer() Returns the number of bytes that are

available in the internal BULK-OUT end-

point buffer.

USBD_BULK_GetNumBytesRemToRead() Get the number of remaining bytes to read

by an active read operation.

USBD_BULK_GetNumBytesRemToWrite()

After starting a non-blocking write oper-

ation this function can be used to period-

ically check how many bytes still have to

be written.

USBD_BULK_Read() Reads data from the host with a given

timeout.

USBD_BULK_ReadOverlapped() Reads data from the host asynchronously.

USBD_BULK_Receive() Reads data from the host.

USBD_BULK_SetContinuousReadMode() Enables continuous read mode for the RX

endpoint.

USBD_BULK_SetOnRXEvent() Sets a callback function for the OUT end-

point that will be called on every RX event

for that endpoint.

USBD_BULK_SetOnTXEvent() Sets a callback function for the IN end-

point that will be called on every TX event

for that endpoint.

USBD_BULK_TxIsPending() Checks whether the TX (IN endpoint) is

currently pending.

95 CHAPTER 5 Target API

Routine Explanation

USBD_BULK_WaitForRX() Waits (blocking) until the triggered USB-

D_BULK_ReadOverlapped() has received

the desired data.

USBD_BULK_WaitForTX() Waits (blocking) until the triggered USB-

D_BULK_WriteOverlapped() has sent the

desired data.

USBD_BULK_WaitForTXReady() Waits (blocking) until the TX queue can ac-

cept another data packet.

USBD_BULK_Write() Sends data to the USB host.

USBD_BULK_WriteEx() Send data to the USB host with NULL pack-

et control.

96 CHAPTER 5 Target API

5.4.2 USB-Bulk functions

5.4.2.1 USBD_BULK_Add()

Description

Adds interface for USB-Bulk communication to emUSB-Device.

Prototype

USB_BULK_HANDLE USBD_BULK_Add(const USB_BULK_INIT_DATA * pInitData);

Parameters

Parameter Description

pInitData Pointer to USB_BULK_INIT_DATA structure.

Return value

Handle to a valid BULK instance. The handle of the first BULK instance is always 0.

Example

Example excerpt from BULK_Echo1.c:

static void _AddBULK(void) {

static U8 _abOutBuffer[USB_HS_BULK_MAX_PACKET_SIZE];

USB_BULK_INIT_DATA Init;

Init.EPIn = USBD_AddEP(USB_DIR_IN,

USB_TRANSFER_TYPE_BULK,

USB_HS_BULK_MAX_PACKET_SIZE,

NULL,

0);

Init.EPOut = USBD_AddEP(USB_DIR_OUT,

USB_TRANSFER_TYPE_BULK,

USB_HS_BULK_MAX_PACKET_SIZE,

_abOutBuffer,

USB_HS_BULK_MAX_PACKET_SIZE);

USBD_BULK_Add(&Init);

}

97 CHAPTER 5 Target API

5.4.2.2 USBD_BULK_Add_Ex()

Description

Adds interface for USB-Bulk communication to emUSB-Device.

Prototype

USB_BULK_HANDLE USBD_BULK_Add_Ex(const USB_BULK_INIT_DATA_EX * pInitData);

Parameters

Parameter Description

pInitData Pointer to USB_BULK_INIT_DATA_EX structure.

Return value

Handle to a valid BULK instance. The handle of the first BULK instance is always 0.

Example

static void _AddBULK(void) {

static U8 _abOutBuffer[USB_HS_BULK_MAX_PACKET_SIZE];

USB_BULK_INIT_DATA_EX Init;

Init.Flags = 0;

Init.EPIn = USBD_AddEP(USB_DIR_IN,

USB_TRANSFER_TYPE_BULK,

USB_HS_BULK_MAX_PACKET_SIZE,

NULL,

0);

Init.EPOut = USBD_AddEP(USB_DIR_OUT,

USB_TRANSFER_TYPE_BULK,

USB_HS_BULK_MAX_PACKET_SIZE,

_abOutBuffer,

USB_HS_BULK_MAX_PACKET_SIZE);

Init.pInterfaceName = "BULK Interface";

USBD_BULK_Add_Ex(&Init);

}

98 CHAPTER 5 Target API

5.4.2.3 USBD_BULK_SetMSDescInfo()

Description

Enables use of Microsoft OS Descriptors. A USB bulk device providing these descriptors is

detected by Windows to be handled by the generic WinUSB driver. For such devices no

other driver needs to be installed.

Prototype

void USBD_BULK_SetMSDescInfo(USB_BULK_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to a valid BULK instance, returned by USBD_BULK_Ad-

d().

Additional information

This function must be called after the call to the function USBD_BULK_Add() and before

USBD_Start().

99 CHAPTER 5 Target API

5.4.2.4 USBD_BULK_CancelRead()

Description

Cancels any non-blocking/blocking read operation that is pending.

Prototype

void USBD_BULK_CancelRead(USB_BULK_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to a valid BULK instance, returned by USBD_BULK_Ad-

d().

Additional information

This function shall be called when a pending asynchronous read operation should be can-

celed. The function can be called from any task. In case of canceling a blocking operation,

this function must be called from another task.

100 CHAPTER 5 Target API

5.4.2.5 USBD_BULK_CancelWrite()

Description

Cancels any non-blocking/blocking write operation that is pending.

Prototype

void USBD_BULK_CancelWrite(USB_BULK_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to a valid BULK instance, returned by USBD_BULK_Ad-

d().

Additional information

This function shall be called when a pending asynchronous write operation should be can-

celed. The function can be called from any task. In case of canceling a blocking operation,

this function must be called from another task.

101 CHAPTER 5 Target API

5.4.2.6 USBD_BULK_GetNumBytesInBuffer()

Description

Returns the number of bytes that are available in the internal BULK-OUT endpoint buffer.

Prototype

unsigned USBD_BULK_GetNumBytesInBuffer(USB_BULK_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to a valid BULK instance, returned by USBD_BULK_Ad-

d().

Return value

Number of bytes that are available in the internal BULK-OUT endpoint buffer.

Additional information

If the host is sending more data than your target application has requested, the remaining

data will be stored in an internal buffer. This function shows how many bytes are available

in this buffer.

The number of bytes returned by this function can be read using USBD_BULK_Read() without

blocking.

Example

Your host application sends 50 bytes. Your target application only requests to receive 1 byte.

In this case the target application will get 1 byte and the remaining 49 bytes are stored in an

internal buffer. When your target application now calls USBD_BULK_GetNumBytesInBuffer()

it will return the number of bytes that are available in the internal buffer (49).

102 CHAPTER 5 Target API

5.4.2.7 USBD_BULK_GetNumBytesRemToRead()

Description

Get the number of remaining bytes to read by an active read operation. This function is to be

used in combination with USBD_BULK_ReadOverlapped(). After starting the read operation

this function can be used to periodically check how many bytes still have to be read.

Prototype

unsigned USBD_BULK_GetNumBytesRemToRead(USB_BULK_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to a valid BULK instance, returned by USBD_BULK_Ad-

d().

Return value

≥ 0 Number of bytes which have not yet been read.

< 0 Error occurred.

Additional information

Alternatively the blocking function USBD_BULK_WaitForRX() can be used.

Example

NumBytesReceived = USBD_BULK_ReadOverlapped(hInst, &ac[0], 50);

if (NumBytesReceived < 0) {

<.. error handling..>

}

if (NumBytesReceived > 0) {

// Already had some data in the internal buffer.

// The first 'NumBytesReceived' bytes may be processed here.

<...>

} else {

// Wait until we get all 50 bytes

while (USBD_BULK_GetNumBytesRemToRead(hInst) > 0) {

USB_OS_Delay(50);

}

103 CHAPTER 5 Target API

5.4.2.8 USBD_BULK_GetNumBytesRemToWrite()

Description

After starting a non-blocking write operation this function can be used to periodically check

how many bytes still have to be written.

Prototype

unsigned USBD_BULK_GetNumBytesRemToWrite(USB_BULK_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to a valid BULK instance, returned by USBD_BULK_Ad-

d().

Return value

≥ 0 Number of bytes which have not yet been written.

< 0 Error occurred.

Additional information

Alternatively the blocking function USBD_BULK_WaitForTX() can be used.

Example

r = USBD_BULK_Write(hInst, &ac[0], TRANSFER_SIZE, -1);

if (r < 0) {

<.. error handling..>

}

// NumBytesToWrite shows how many bytes still have to be written.

while (USBD_BULK_GetNumBytesRemToWrite(hInst) > 0) {

USB_OS_Delay(50);

}

104 CHAPTER 5 Target API

5.4.2.9 USBD_BULK_Read()

Description

Reads data from the host with a given timeout.

Prototype

int USBD_BULK_Read(USB_BULK_HANDLE hInst,

void * pData,

unsigned NumBytes,

unsigned Timeout);

Parameters

Parameter Description

hInst Handle to a valid BULK instance, returned by USBD_BULK_Ad-

d().

pData Pointer to a buffer where the received data will be stored.

NumBytes Number of bytes to read.

Timeout Timeout in milliseconds, 0 means infinite.

Return value

= NumBytes Requested data was successfully read within the given timeout.

≥ 0 && < NumBytes Timeout has occurred. Number of bytes that have been read

within the given timeout.

< 0 Error occurred.

Additional information

This function blocks a task until all data have been read or a timeout expires. This function

also returns when the device is disconnected from host or when a USB reset occurs.

If the USB stack receives a data packet from the host containing more bytes than requested,

the remaining bytes are stored into the internal buffer of the endpoint, that was provided

via USBD_AddEP(). This data can be retrieved by a later call to USBD_BULK_Receive() /

USBD_BULK_Read(). See also USBD_BULK_GetNumBytesInBuffer().

If a read transfer was still pending while the function is called, it returns USB_S-

TATUS_EP_BUSY.

105 CHAPTER 5 Target API

5.4.2.10 USBD_BULK_ReadOverlapped()

Description

Reads data from the host asynchronously.

Prototype

int USBD_BULK_ReadOverlapped(USB_BULK_HANDLE hInst,

void * pData,

unsigned NumBytes);

Parameters

Parameter Description

hInst Handle to a valid BULK instance, returned by USBD_BULK_Ad-

d().

pData Pointer to a buffer where the received data will be stored.

NumBytes Number of bytes to read.

Return value

> 0 Number of bytes that have been read from the internal buffer (success).

= 0 No data was found in the internal buffer (success).

< 0 Error occurred.

Additional information

This function will not block the calling task. The read transfer will be initiated and the

function returns immediately. In order to synchronize, USBD_BULK_WaitForRX() needs to

be called. Alternatively the function USBD_BULK_GetNumBytesRemToRead() can be called

periodically to check whether all bytes have been read or not. The read operation can be

canceled using USBD_BULK_CancelRead(). The buffer pointed to by pData must be valid

until the read operation is terminated.

If a read transfer was still pending while the function is called, it returns USB_S-

TATUS_EP_BUSY.

Example

See USBD_BULK_GetNumBytesRemToRead on page 102.

106 CHAPTER 5 Target API

5.4.2.11 USBD_BULK_Receive()

Description

Reads data from the host. The function blocks until any data has been received or a timeout

occurs (if Timeout ≥ 0). In contrast to USBD_BULK_Read() this function does not wait for

all of NumBytes to be received, but returns after the first packet has been received.

Prototype

int USBD_BULK_Receive(USB_BULK_HANDLE hInst,

void * pData,

unsigned NumBytes,

int Timeout);

Parameters

Parameter Description

hInst Handle to a valid BULK instance, returned by USBD_BULK_Ad-

d().

pData Pointer to a buffer where the received data will be stored.

NumBytes Maximum number of bytes to read.

Timeout Timeout in milliseconds. 0 means infinite. If Timeout is -1,

the function never blocks.

Return value

> 0 Number of bytes that have been read.

= 0 A timeout occurred (if Timeout > 0), zero packet received (not every controller

supports this!), no data in buffer (if Timeout < 0) or the target was disconnect-

ed during the function call and no data was read so far.

< 0 Error occurred.

Additional information

If no error occurs, this function returns the number of bytes received. Calling USB-

D_BULK_Receive() will return as much data as is currently available -- up to the size of the

buffer specified. This function also returns when the target is disconnected from the host or

when a USB reset occurred during the function call, it will then return USB_STATUS_ERROR.

If a read transfer was pending while the function is called, it returns USB_STATUS_EP_BUSY.

If the USB stack receives a data packet from the host containing more bytes than requested,

the remaining bytes are stored into the internal buffer of the endpoint, that was provided

via USBD_AddEP(). This data can be retrieved by a later call to USBD_BULK_Receive() /

USBD_BULK_Read(). See also USBD_BULK_GetNumBytesInBuffer().

A call of USBD_BULK_Receive(Inst, NULL, 0, -1) can be used to trigger an asynchronous

read that stores the data into the internal buffer.

107 CHAPTER 5 Target API

5.4.2.12 USBD_BULK_SetContinuousReadMode()

Description

Enables continuous read mode for the RX endpoint. In this mode every finished read transfer

will automatically trigger another read transfer, as long as there is enough space in the

internal buffer to receive another packet.

Prototype

void USBD_BULK_SetContinuousReadMode(USB_BULK_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to a valid BULK instance, returned by USBD_BULK_Ad-

d().

Additional information

To check how many bytes have been read into the buffer, the function USBD_BULK_GetNum-

BytesInBuffer() may be called. In order to read the data the function USBD_BULK_Re-

ceive() needs to be called (non-blocking).

The USB stack will use the buffer that was provided by the application with USBD_AddEP().

The transfer speed may be improved, if this buffer has a size of at least 2 * MaxPacketSize.

Normally MaxPacketSize for full-speed devices is 64 bytes and for high-speed devices 512

bytes.

Example

USBD_BULK_SetContinuousReadMode(hInst);

<...>

for(;;) {

// Fetch data that was already read (non-blocking).

NumBytesReceived = USBD_BULK_Receive(hInst, &ac[0], sizeof(ac), -1);

if (NumBytesReceived > 0) {

// We got some data

<.. Process data..>

} else {

<.. Nothing received yet, do application processing..>

}

108 CHAPTER 5 Target API

5.4.2.13 USBD_BULK_SetOnRXEvent()

Description

Sets a callback function for the OUT endpoint that will be called on every RX event for

that endpoint.

Prototype

void USBD_BULK_SetOnRXEvent(USB_BULK_HANDLE hInst,

USB_EVENT_CALLBACK * pEventCb,

USB_EVENT_CALLBACK_FUNC * pfEventCb,

void * pContext);

Parameters

Parameter Description

hInst Handle to a valid BULK instance, returned by USBD_BULK_Ad-

d().

pEventCb Pointer to a USB_EVENT_CALLBACK structure. The structure is

initialized by this function.

pfEventCb Pointer to the callback routine that will be called on every

event on the USB endpoint.

pContext A pointer which is used as parameter for the callback func-

tion.

Additional information

The USB_EVENT_CALLBACK structure is private to the USB stack. It will be initialized by

USBD_BULK_SetOnRXEvent(). The USB stack keeps track of all event callback functions

using a linked list. The USB_EVENT_CALLBACK structure will be included into this linked list

and must reside in static memory.

The callback function is called only, if a read operation was started using one of the USB-

D_BULK_Read…() functions.

The callback function has the following prototype:

typedef void USB_EVENT_CALLBACK_FUNC(unsigned Events, void *pContext);

Parameter Description

Events A bit mask indicating which events occurred on the

endpoint.

pContext The pointer which was provided to the USBD_SetOn-

Event() function.

Note that the callback function will be called within an ISR, therefore it should never block.

The first parameter to the callback function will contain a bit mask for all events that trig-

gered the call:

Event Description

USB_EVENT_DATA_READ Some data was received from the host on the end-

point.

USB_EVENT_READ_COMPLETE The last read operation was completed.

USB_EVENT_READ_ABORT A read transfer was aborted.

109 CHAPTER 5 Target API

Example

// The callback function.

static void _OnEvent(unsigned Events, void *pContext) {

unsigned NumBytes;

if (Events & USB_EVENT_DATA_READ) {

NumBytes = USBD_BULK_GetNumBytesRemToRead(hInst);

if (NumBytes) {

r = USBD_BULK_Receive(hInst, Buff, NumBytes, -1);

if (r > 0) {

<.. process data in Buff..>

}

// Main program.

// Register callback function.

static USB_EVENT_CALLBACK _usb_callback;

USBD_BULK_SetOnRXEvent(hInst, &_usb_callback, _OnEvent, NULL);

USBD_BULK_SetContinuousReadMode(hInst);

// Trigger first read

USBD_BULK_Receive(Inst, NULL, 0, -1);

<.. do anything else here while the data is processed in the callback ..>

110 CHAPTER 5 Target API

5.4.2.14 USBD_BULK_SetOnTXEvent()

Description

Sets a callback function for the IN endpoint that will be called on every TX event for that

endpoint.

Prototype

void USBD_BULK_SetOnTXEvent(USB_BULK_HANDLE hInst,

USB_EVENT_CALLBACK * pEventCb,

USB_EVENT_CALLBACK_FUNC * pfEventCb,

void * pContext);

Parameters

Parameter Description

hInst Handle to a valid BULK instance, returned by USBD_BULK_Ad-

d().

pEventCb Pointer to a USB_EVENT_CALLBACK structure. The structure is

initialized by this function.

pfEventCb Pointer to the callback routine that will be called on every

event on the USB endpoint.

pContext A pointer which is used as parameter for the callback func-

tion.

Additional information

The USB_EVENT_CALLBACK structure is private to the USB stack. It will be initialized by

USBD_BULK_SetOnTXEvent(). The USB stack keeps track of all event callback functions

using a linked list. The USB_EVENT_CALLBACK structure will be included into this linked list

and must reside in static memory.

The callback function is called only, if a write operation was started using one of the USB-

D_BULK_Write…() functions.

The callback function has the following prototype:

typedef void USB_EVENT_CALLBACK_FUNC(unsigned Events, void *pContext);

Parameter Description

Events A bit mask indicating which events occurred on the

endpoint.

pContext The pointer which was provided to the USBD_SetOn-

Event() function.

Note that the callback function will be called within an ISR, therefore it should never block.

The first parameter to the callback function will contain a bit mask for all events that trig-

gered the call:

Event Description

USB_EVENT_DATA_SEND Some data was send to the host, so that (part of)

the user write buffer may be reused by the applica-

tion.

USB_EVENT_DATA_ACKED Some data was acknowledged by the host.

USB_EVENT_WRITE_ABORT A write transfer was aborted.

USB_EVENT_WRITE_COMPLETE All write operations were completed.

111 CHAPTER 5 Target API

Example

// The callback function.

static void _OnEvent(unsigned Events, void *pContext) {

if ((Events & USB_EVENT_DATA_SEND) != 0 &&

// Check for last write transfer to be completed.

USBD_BULK_GetNumBytesRemToWrite(_hInst) == 0) {

<.. prepare next data for writing..>

// Send next packet of data.

r = USBD_BULK_Write(_hInst, &ac[0], 200, -1);

if (r < 0) {

<.. error handling..>

}

// Main program.

// Register callback function.

static USB_EVENT_CALLBACK _usb_callback;

USBD_BULK_SetOnTXEvent(hInst, &_usb_callback, _OnEvent, NULL);

// Send the first packet of data using an asynchronous write operation.

r = USBD_BULK_Write(_hInst, &ac[0], 200, -1);

if (r < 0) {

<.. error handling..>

}

<.. do anything else here while the whole data is send..>

112 CHAPTER 5 Target API

5.4.2.15 USBD_BULK_TxIsPending()

Description

Checks whether the TX (IN endpoint) is currently pending. Can be called in any context.

Prototype

int USBD_BULK_TxIsPending(USB_BULK_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to a valid BULK instance, returned by USBD_BULK_Ad-

d().

Return value

1 We have queued data to be sent.

0 Queue is empty.

113 CHAPTER 5 Target API

5.4.2.16 USBD_BULK_WaitForRX()

Description

Waits (blocking) until the triggered USBD_BULK_ReadOverlapped() has received the desired

data.

Prototype

int USBD_BULK_WaitForRX(USB_BULK_HANDLE hInst,

unsigned Timeout);

Parameters

Parameter Description

hInst Handle to a valid BULK instance, returned by USBD_BULK_Ad-

d().

Timeout Timeout in milliseconds. 0 means infinite.

Return value

= 0 Transfer completed.

= 1 Timeout occurred.

< 0 An error occurred (e.g. target disconnected)

Additional information

In case of a timeout, a current transfer is canceled.

114 CHAPTER 5 Target API

5.4.2.17 USBD_BULK_WaitForTX()

Description

Waits (blocking) until the triggered USBD_BULK_WriteOverlapped() has sent the desired

data.

Prototype

int USBD_BULK_WaitForTX(USB_BULK_HANDLE hInst,

unsigned Timeout);

Parameters

Parameter Description

hInst Handle to a valid BULK instance, returned by USBD_BULK_Ad-

d().

Timeout Timeout in milliseconds. 0 means infinite.

Return value

= 0 Transfer completed.

= 1 Timeout occurred.

< 0 An error occurred (e.g. target disconnected)

Additional information

In case of a timeout, a current transfer is canceled.

115 CHAPTER 5 Target API

5.4.2.18 USBD_BULK_WaitForTXReady()

Description

Waits (blocking) until the TX queue can accept another data packet. This function is used

in combination with a non-blocking call to USBD_BULK_Write() , it waits until a new asyn-

chronous write data transfer will be accepted by the USB stack.

Prototype

int USBD_BULK_WaitForTXReady(USB_BULK_HANDLE hInst,

int Timeout);

Parameters

Parameter Description

hInst Handle to a valid BULK instance, returned by USBD_BULK_Ad-

d().

Timeout Timeout in milliseconds. 0 means infinite. If Timeout is neg-

ative, the function will return immediately.

Return value

= 0 A new asynchronous write data transfer will be accepted.

= 1 The write queue is full, a call to USBD_BULK_Write() would return USB_S-

TATUS_EP_BUSY.

< 0 Error occurred.

Additional information

If Timeout is 0, the function never returns 1.

If Timeout is -1, the function will not wait, but immediately return the current state.

Example

// Always keep the write queue full for maximum send speed.

for (;;) {

pData = GetNextData(&NumBytes);

// Wait until stack can accept a new write.

USBD_BULK_WaitForTxReady(hInst, 0);

// Issue write transfer.

if (USBD_BULK_Write(hInst, pData, NumBytes, -1) < 0) {

<.. error handling..>

}

116 CHAPTER 5 Target API

5.4.2.19 USBD_BULK_Write()

Description

Sends data to the USB host. Depending on the Timeout parameter, the function may block

until NumBytes have been written or a timeout occurs.

Prototype

int USBD_BULK_Write( USB_BULK_HANDLE hInst,

const void * pData,

unsigned NumBytes,

int Timeout);

Parameters

Parameter Description

hInst Handle to a valid BULK instance, returned by USBD_BULK_Ad-

d().

pData Data that should be written.

NumBytes Number of bytes to write.

Timeout Timeout in milliseconds. 0 means infinite. If Timeout is

-1, the function returns immediately and the transfer is

processed asynchronously.

Return value

= 0 Successful started an asynchronous write transfer or a timeout

has occurred and no data was written.

> 0 && < NumBytes Number of bytes that have been written before a timeout oc-

curred.

= NumBytes Write transfer successful completed.

< 0 Error occurred.

Additional information

This function also returns when the target is disconnected from host or when a USB reset

occurred.

The USB stack is able to queue a small number of asynchronous write transfers (Timeout

= -1). If a write transfer is still in progress when this function is called and the USB stack

can not accept another write transfer request, the functions returns USB_STATUS_EP_BUSY.

A synchronous write transfer (Timeout ≥ 0) will always block until the transfer (including

all pending transfers) are finished or a timeout occurs.

In order to synchronize, USBD_BULK_WaitForTX() needs to be called. Another synchroniza-

tion method would be to periodically call USBD_BULK_GetNumBytesRemToWrite() in order

to see how many bytes still need to be written (this method is preferred when a non-block-

ing solution is necessary). The write operation can be canceled using USBD_BULK_Cancel-

Write().

If pData = NULL and NumBytes = 0, a zero-length packet is sent to the host.

The content of the buffer pointed to by pData must not be changed until the transfer has

been completed.

Example

NumBytesWritten = USBD_BULK_Write(hInst, &ac[0], DataSize, 500);

if (NumBytesWritten < 0) {

<.. error handling..>

}

if (NumBytesWritten < DataSize) {

117 CHAPTER 5 Target API

<.. timeout occurred, not all data were written within 500ms ..>

} else {

<.. write successful completed ..>

}

See also USBD_BULK_GetNumBytesRemToWrite on page 103.

118 CHAPTER 5 Target API

5.4.2.20 USBD_BULK_WriteEx()

Description

Send data to the USB host with NULL packet control. This function behaves exactly like

USBD_BULK_Write(). Additionally sending of a zero length packet after sending the data

can be suppressed by setting Send0PacketIfRequired = 0.

Prototype

int USBD_BULK_WriteEx( USB_BULK_HANDLE hInst,

const void * pData,

unsigned NumBytes,

char Send0PacketIfRequired,

int Timeout);

Parameters

Parameter Description

hInst Handle to a valid BULK instance, returned by USBD_BULK_Ad-

d().

pData Pointer to a buffer that contains the written data.

NumBytes Number of bytes to write.

Send0PacketIfRequired

Specifies that a zero-length packet shall be sent when the

last data packet is a multiple of MaxPacketSize. Normally

MaxPacketSize for full-speed devices is 64 bytes. For high-

speed devices the normal packet size is between 64 and 512

bytes.

Timeout Timeout in milliseconds. 0 means infinite. If Timeout is

-1, the function returns immediately and the transfer is

processed asynchronously.

Return value

= 0 Successful started an asynchronous write transfer or a timeout

has occurred and no data was written.

> 0 && < NumBytes Number of bytes that have been written before a timeout oc-

curred.

= NumBytes Write transfer successful completed.

< 0 Error occurred.

Additional information

Normally USBD_BULK_Write() is called to let the stack send the data to the host and send

an optional zero-length packet to tell the host that this was the last packet. This is the

case when the last packet sent is MaxPacketSize bytes in size. When using this function,

the zero-length packet handling can be controlled. This means the function can be called

when sending data in multiple steps.

Example

// for high speed devices

USBD_BULK_Write(hInst, _aBuffer1, 512, 0);

USBD_BULK_Write(hInst, _aBuffer2, 512, 0);

USBD_BULK_Write(hInst, _aBuffer3, 512, 0);

// this will send 6 packets to the host with sizes: 512, 0, 512, 0, 512, 0

USBD_BULK_WriteEx(hInst, _aBuffer1, 512, 0, 0);

USBD_BULK_WriteEx(hInst, _aBuffer2, 512, 0, 0);

USBD_BULK_WriteEx(hInst, _aBuffer3, 512, 0, 1);

// this will send 4 packets to the host with sizes: 512, 512, 512, 0

119 CHAPTER 5 Target API

5.4.3 Data structures

5.4.3.1 USB_BULK_INIT_DATA

Description

Initialization structure that is needed when adding a BULK interface to emUSB-Device.

Type definition

typedef struct {

U8 EPIn;

U8 EPOut;

} USB_BULK_INIT_DATA;

Structure members

Member Description

EPIn Endpoint for sending data to the host.

EPOut Endpoint for receiving data from the host.

120 CHAPTER 5 Target API

5.4.3.2 USB_BULK_INIT_DATA_EX

Description

Initialization structure that is needed when adding a BULK interface to emUSB-Device.

Type definition

typedef struct {

U16 Flags;

U8 EPIn;

U8 EPOut;

const char * pInterfaceName;

} USB_BULK_INIT_DATA_EX;

Structure members

Member Description

Flags Reserved for future use, must be 0.

EPIn Endpoint for sending data to the host.

EPOut Endpoint for receiving data from the host.

pInterfaceName Name of the interface.

121 CHAPTER 5 Target API

5.4.4 Multithreading

The emUSB BULK target API is not generally thread safe. But it is allowed to handle different

endpoints in different tasks in parallel. Examples are:

• A task that performs all reads of data from the host while another task sends data to

the host.

• Operating on different interfaces (e.g. a BULK and a CDC interface) in independent

tasks.

122 CHAPTER 5 Host API

5.5 Host API

This chapter describes the functions that can be used with the host system.

To communicate with the target USB-Bulk stack an API is provided that can be used on

Windows, Linux and macOS systems.

To have an easy start-up when writing an application on the host side, these API functions

have a simple interface and handle all required operations to communicate with the target

USB-Bulk stack.

Therefore, all operations that need to open a channel, writing to or reading from the USB-

Bulk stack, are handled internally by the provided API functions.

To use the API in an application the header file USBBULK.h must be included. Depending

on the host operating system used the following components must be added to the host

application:

• Windows: USBBULK.lib and USBBULK.dll (These files are provided for 32- and 64-Bit

applications).

• Linux: USBBULK_Linux.c.

• macOS: USBBULK_MacOSX.c.

123 CHAPTER 5 Host API

5.5.1 Bulk Host API list

The functions below are available on the host (PC) side.

Function Description

USB-Bulk Basic functions

USBBULK_Init() This function needs to be called first.

USBBULK_Exit() This is a cleanup function, it shall be called

when exiting the application.

USBBULK_AddAllowedDeviceItem() Adds the Vendor and Product ID to the list

of devices the USBBULK API should look

for.

USBBULK_GetNumAvailableDevices() Returns the number of connected USB-

Bulk devices.

USBBULK_Open() Opens an existing device.

USBBULK_Close() Closes an opened device.

USB-Bulk direct input/output functions

USBBULK_Read() Reads data from target device running

emUSB-Device-Bulk.

USBBULK_ReadTimed() Reads data from target device running

emUSB-Device-Bulk within a given time-

out.

USBBULK_Write() Writes data to the device.

USBBULK_WriteTimed() Writes data to the device within a given

timeout.

USBBULK_CancelRead() This cancels an initiated read.

USBBULK_FlushRx() Flush the any received data.

USB-Bulk Control functions

USBBULK_SetMode() Sets the read and write mode for a speci-

fied device running emUSB-Device-Bulk.

USBBULK_GetMode() Returns the current mode of the device.

USBBULK_SetReadTimeout() Sets the default read timeout for an

opened device.

USBBULK_SetWriteTimeout() Sets a default write timeout for an opened

device.

USBBULK_ResetPipe() Resets the pipes that are opened to the

device.

USBBULK_ResetDevice() Resets the device via a USB reset.

USB-Bulk general GET functions

USBBULK_GetVersion() Returns the version number of the USB-

BULK API.

USBBULK_GetDevInfo() Retrieves information about an opened

USBBULK device.

USBBULK_GetDevInfoByIdx() Retrieves information about a USB device.

USBBULK_GetUSBId() Returns the Product and Vendor ID of an

opened device.

USBBULK_GetProductName() Retrieves the device/product name if avail-

able.

USBBULK_GetVendorName() Retrieves the vendor name of an opened

USBBULK device.

124 CHAPTER 5 Host API

Function Description

USBBULK_GetSN() Retrieves the USB serial number as a

string which was sent by the device during

the enumeration.

USBBULK_GetConfigDescriptor() Gets the received target USB configuration

descriptor of a specified device.

125 CHAPTER 5 Host API

5.5.2 USB-Bulk Basic functions

5.5.2.1 USBBULK_Init()

Description

This function needs to be called first. This makes sure to have all structures and thread

have been initialized. It also sets a callback in order to be notified when a device is added

or removed.

Prototype

void USBBULK_Init(USBBULK_NOTIFICATION_FUNC * pfNotification,

void * pContext);

Parameters

Parameter Description

pfNotification Pointer to the user callback.

pContext Context data that shall be called with the callback function.

Example

/*********************************************************************

* _OnDevNotify

* Function description:

* Is called when a new device is found or an existing device is removed.

* Parameters:

* pContext - Pointer to a context given when USBBULK_Init is called

* Index - Device Index that has been added or removed.

* Event - Type of event, currently the following are available:

* USBBULK_DEVICE_EVENT_ADD

* USBBULK_DEVICE_EVENT_REMOVE

static void _OnDevNotify(void * pContext,

unsigned Index,

USBBULK_DEVICE_EVENT Event) {

switch(Event) {

case USBBULK_DEVICE_EVENT_ADD:

printf("The following DevIndex has been added: %d", Index);

NumDevices = USBBULK_GetNumAvailableDevices(&DeviceMask);

break;

case USBBULK_DEVICE_EVENT_REMOVE:

printf("The following DevIndex has been removed: %d", Index);

NumDevices = USBBULK_GetNumAvailableDevices(&DeviceMask);

break;

}

void MainTask(void) {

<...>

USBBULK_Init(_OnDevNotify, NULL);

<...>

}

126 CHAPTER 5 Host API

5.5.2.2 USBBULK_Exit()

Description

This is a cleanup function, it shall be called when exiting the application.

Prototype

void USBBULK_Exit(void);

Additional information

We recommend to call this function before exiting the application in order to remove all

handles and resources that have been allocated.

127 CHAPTER 5 Host API

5.5.2.3 USBBULK_AddAllowedDeviceItem()

Description

Adds the Vendor and Product ID to the list of devices the USBBULK API should look for.

Prototype

void USBBULK_AddAllowedDeviceItem(U16 VendorId,

U16 ProductId);

Parameters

Parameter Description

VendorId The desired Vendor ID mask that shall be used with the

USBBULK API.

ProductId The desired Product ID mask that shall be used with the

USBBULK API.

Additional information

It is necessary to call this function first before calling USBBULK_GetNumAvailableDevices()

or opening any connection to a device.

The function can be called multiple times to handle more than one pairs of Vendor and

Product IDs with the API.

128 CHAPTER 5 Host API

5.5.2.4 USBBULK_GetNumAvailableDevices()

Description

Returns the number of connected USB-Bulk devices.

Prototype

unsigned USBBULK_GetNumAvailableDevices(U32 * pMask);

Parameters

Parameter Description

pMask Pointer to a U32 variable to receive the connected device

mask. This parameter can be NULL.

Return value

Number of available devices running emUSB-Device-Bulk.

Additional information

For each emUSB-Device device that is connected, a bit in pMask is set. For example if device

0 and device 2 are connected to the host, the value pMask points to will be 0x00000005.

129 CHAPTER 5 Host API

5.5.2.5 USBBULK_Open()

Description

Opens an existing device. The ID of the device can be retrieved by the function USB-

BULK_GetNumAvailableDevices() via the pDeviceMask parameter. Each bit set in the De-

viceMask represents an available device. Currently 32 devices can be managed at once.

Prototype

USB_BULK_HANDLE USBBULK_Open(unsigned Id);

Parameters

Parameter Description

Id Device ID to be opened (0..31).

Return value

≠ 0 Handle to the opened device.

= 0 Error occurred.

130 CHAPTER 5 Host API

5.5.2.6 USBBULK_Close()

Description

Closes an opened device.

Prototype

void USBBULK_Close(USB_BULK_HANDLE hDevice);

Parameters

Parameter Description

hDevice Handle to the device that shall be closed.

131 CHAPTER 5 Host API

5.5.3 USB-Bulk direct input/output functions

5.5.3.1 USBBULK_Read()

Description

Reads data from target device running emUSB-Device-Bulk.

Prototype

int USBBULK_Read(USB_BULK_HANDLE hDevice,

void * pBuffer,

int NumBytes);

Parameters

Parameter Description

hDevice Handle to the opened device.

pBuffer Pointer to a buffer that shall receive the data.

NumBytes Number of bytes to be read.

Return value

= NumBytes All bytes have been successfully read.

> 0, < NumBytes Number of bytes that have been read. If short read transfers are

not allowed (normal mode) this indicates a timeout.

= 0 A timeout occurred, no data was read.

< 0 Error occurred.

Additional information

If short read transfers are allowed (see USBBULK_SetMode()) the function returns as soon

as data is available, even if just a single byte was read. Otherwise the function blocks until

NumBytes were read. In both cases the function returns if a timeout occurs. The default

timeout used can be set with USBBULK_SetReadTimeout().

If NumBytes exceeds the maximum read size the driver can handle (the default value is

64 Kbytes), USBBULK_Read() will read the desired NumBytes in chunks of the maximum

read size.

132 CHAPTER 5 Host API

5.5.3.2 USBBULK_ReadTimed()

Description

Reads data from target device running emUSB-Device-Bulk within a given timeout.

Prototype

int USBBULK_ReadTimed(USB_BULK_HANDLE hDevice,

void * pBuffer,

int NumBytes,

unsigned ms);

Parameters

Parameter Description

hDevice Handle to the opened device.

pBuffer Pointer to a buffer that shall receive the data.

NumBytes Maximum number of bytes to be read.

ms Timeout in milliseconds.

Return value

> 0 Number of bytes that have been read.

= 0 A timeout occurred during read.

< 0 Error, cannot read from the device.

Additional information

The function returns as soon as data is available, even if just a single byte was read. If no

data is available, the functions return after the given timeout was expired.

If NumBytes exceeds the maximum read size the driver can handle (the default value is 64

Kbytes), USBBULK_ReadTimed() will read the desired NumBytes in chunks of the maximum

read size.

133 CHAPTER 5 Host API

5.5.3.3 USBBULK_Write()

Description

Writes data to the device.

Prototype

int USBBULK_Write( USB_BULK_HANDLE hDevice,

const void * pBuffer,

int NumBytes);

Parameters

Parameter Description

hDevice Handle to the opened device.

pBuffer Pointer to a buffer that contains the data.

NumBytes Number of bytes to be written. If NumBytes = 0, a zero

length packet is written to the device.

Return value

= NumBytes All bytes have been successfully written.

> 0, < NumBytes Number of bytes that have been written. If short read transfers are

not allowed (normal mode) this indicates a timeout.

= 0 A timeout occurred, no data was written.

< 0 Error, cannot write to the device.

Additional information

If short write transfers are allowed (see USBBULK_SetMode()) the function returns after

writing the minimal amount of data (either NumBytes or the maximal write transfer size).

Otherwise the function blocks until NumBytes were written. In both cases the function re-

turns if a timeout occurs. The default timeout used can be set with USBBULK_SetWrite-

Timeout().

If NumBytes exceeds the maximum write size the driver can handle (the default value is

64 Kbytes), USBBULK_Write() will write the desired NumBytes in chunks of the maximum

write size.

134 CHAPTER 5 Host API

5.5.3.4 USBBULK_WriteTimed()

Description

Writes data to the device within a given timeout.

Prototype

int USBBULK_WriteTimed( USB_BULK_HANDLE hDevice,

const void * pBuffer,

int NumBytes,

unsigned ms);

Parameters

Parameter Description

hDevice Handle to the opened device.

pBuffer Pointer to a buffer that contains the data.

NumBytes Number of bytes to be written. If NumBytes = 0, a zero

length packet is written to the device.

ms Timeout in milliseconds.

Return value

= NumBytes All bytes have been successfully written.

> 0, < NumBytes Number of bytes that have been written. If short read transfers are

not allowed (normal mode) this indicates a timeout.

= 0 A timeout occurred, no data was written.

< 0 Error, cannot write to the device.

Additional information

If short write transfers are allowed (see USBBULK_SetMode()) the function returns after

writing the minimal amount of data (either NumBytes or the maximal write transfer size).

Otherwise the function blocks until NumBytes were written. In both cases the function re-

turns if a timeout occurs.

If NumBytes exceeds the maximum write size the driver can handle (the default value is 64

Kbytes), USBBULK_WriteTimed() will write the desired NumBytes in chunks of the maximum

write size.

135 CHAPTER 5 Host API

5.5.3.5 USBBULK_CancelRead()

Description

This cancels an initiated read.

Prototype

void USBBULK_CancelRead(USB_BULK_HANDLE hDevice);

Parameters

Parameter Description

hDevice Handle to the opened device.

Additional information

Not supported on Linux and MacOSX.

136 CHAPTER 5 Host API

5.5.3.6 USBBULK_FlushRx()

Description

Flush the any received data.

Prototype

int USBBULK_FlushRx(USB_BULK_HANDLE hDevice);

Parameters

Parameter Description

hDevice Handle to the opened device.

Return value

= 0 Error, bad handle.

≠ 0 Success, flushing the RX buffer was successful.

137 CHAPTER 5 Host API

5.5.4 USB-Bulk Control functions

5.5.4.1 USBBULK_SetMode()

Description

Sets the read and write mode for a specified device running emUSB-Device-Bulk.

Prototype

unsigned USBBULK_SetMode(USB_BULK_HANDLE hDevice,

unsigned Mode);

Parameters

Parameter Description

hDevice Handle to the opened device.

Mode

Read and write mode for the USB-Bulk driver. This is a com-

bination of the following flags, combined by binary or:

•USBBULK_MODE_BIT_ALLOW_SHORT_READ

•USBBULK_MODE_BIT_ALLOW_SHORT_WRITE

Return value

= 0 Operation failed (invalid handle).

≠ 0 The operation was successful.

Additional information

USBBULK_MODE_BIT_ALLOW_SHORT_READ allows short read transfers. Short transfers are

transfers of less bytes than requested. If this bit is specified, the read function USB-

BULK_Read() returns as soon as data is available, even if it is just a single byte.

USBBULK_MODE_BIT_ALLOW_SHORT_WRITE allows short write transfers. USBBULK_Write()

and USBBULK_WriteTimed() return after writing the minimal amount of data (either Num-

Bytes or the maximal write transfer size).

Example

static void _TestMode(USB_BULK_HANDLE hDevice) {

unsigned Mode;

char * pText;

Mode = USBBULK_GetMode(hDevice);

if (Mode & USBBULK_MODE_BIT_ALLOW_SHORT_READ) {

pText = "USE_SHORT_MODE";

} else {

pText = "USE_NORMAL_MODE";

}

printf("USB-Bulk driver is in %s for device %d\n", pText, (int)hDevice);

printf("Set mode to USBBULK_MODE_BIT_ALLOW_SHORT_READ\n");

USBBULK_SetMode(hDevice, USBBULK_MODE_BIT_ALLOW_SHORT_READ);

Mode = USBBULK_GetMode(hDevice);

if (Mode & USBBULK_MODE_BIT_ALLOW_SHORT_READ) {

pText = "USE_SHORT_MODE";

} else {

pText = "USE_NORMAL_MODE";

}

printf("USB-Bulk driver is now in %s for device %d\n", pText,(int)hDevice);

}

138 CHAPTER 5 Host API

5.5.4.2 USBBULK_GetMode()

Description

Returns the current mode of the device.

Prototype

unsigned USBBULK_GetMode(USB_BULK_HANDLE hDevice);

Parameters

Parameter Description

hDevice Handle to the opened device.

Return value

A combination of the following flags, combined by binary or:

•USBBULK_MODE_BIT_ALLOW_SHORT_READ - Short read mode is enabled.

•USBBULK_MODE_BIT_ALLOW_SHORT_WRITE - Short write mode is enabled.

139 CHAPTER 5 Host API

5.5.4.3 USBBULK_SetReadTimeout()

Description

Sets the default read timeout for an opened device.

Prototype

void USBBULK_SetReadTimeout(USB_BULK_HANDLE hDevice,

int Timeout);

Parameters

Parameter Description

hDevice Handle to the opened device.

Timeout Timeout in milliseconds.

140 CHAPTER 5 Host API

5.5.4.4 USBBULK_SetWriteTimeout()

Description

Sets a default write timeout for an opened device.

Prototype

void USBBULK_SetWriteTimeout(USB_BULK_HANDLE hDevice,

int Timeout);

Parameters

Parameter Description

hDevice Handle to the opened device.

Timeout Timeout in milliseconds.

141 CHAPTER 5 Host API

5.5.4.5 USBBULK_ResetPipe()

Description

Resets the pipes that are opened to the device. It also flushes any data the USB bulk driver

would cache.

Prototype

int USBBULK_ResetPipe(USB_BULK_HANDLE hDevice);

Parameters

Parameter Description

hDevice Handle to the opened device.

Return value

≠ 0 The operation was successful.

= 0 Operation failed. Either an invalid handle was used or the pipes cannot be

flushed.

142 CHAPTER 5 Host API

5.5.4.6 USBBULK_ResetDevice()

Description

Resets the device via a USB reset. This can be used when the device does not work properly

and may be reactivated via USB reset. This will force a re-enumeration of the device.

Prototype

int USBBULK_ResetDevice(USB_BULK_HANDLE hDevice);

Parameters

Parameter Description

hDevice Handle to the opened device.

Return value

≠ 0 The operation was successful.

= 0 Operation failed. Either an invalid handle was used or the device cannot be re-

set.

Additional information

After the device has been reset it is necessary to re-open the device as the current handle

will become invalid.

143 CHAPTER 5 Host API

5.5.5 USB-Bulk general GET functions

5.5.5.1 USBBULK_GetVersion()

Description

Returns the version number of the USBBULK API.

Prototype

unsigned USBBULK_GetVersion(void);

Return value

Version number, format:

< Major Version><Minor Version><Subversion> (Mmmrr, decimal).

Example: 30203 is 3.02c

144 CHAPTER 5 Host API

5.5.5.2 USBBULK_GetDevInfo()

Description

Retrieves information about an opened USBBULK device.

Prototype

void USBBULK_GetDevInfo(USB_BULK_HANDLE hDevice,

USBBULK_DEV_INFO * pDevInfo);

Parameters

Parameter Description

hDevice Handle to the opened device.

pDevInfo Pointer to a device info structure.

Additional information

USBBULK_DEV_INFO is defined as follows:

typedef struct {

U16 VendorId;

U16 ProductId;

char acSN[256];

char acDevName[255];

U8 InterfaceNo;

};

Member Description

VendorId Vendor ID of the device.

ProductId Product ID of the device.

acSN 0-terminated string which holds the serial number of the device.

acDevName 0-terminated string which holds the device name.

InterfaceNo Interface number used by this device.

145 CHAPTER 5 Host API

5.5.5.3 USBBULK_GetDevInfoByIdx()

Description

Retrieves information about a USB device.

Prototype

int USBBULK_GetDevInfoByIdx(unsigned Idx,

USBBULK_DEV_INFO * pDevInfo);

Parameters

Parameter Description

Idx Index of the device.

pDevInfo Pointer to a device info structure.

Return value

= 0; Error, bad device index.

≠ 0 Success

Additional information

See USBBULK_GetDevInfo() for a description of the structure USBBULK_DEV_INFO.

146 CHAPTER 5 Host API

5.5.5.4 USBBULK_GetUSBId()

Description

Returns the Product and Vendor ID of an opened device.

Prototype

void USBBULK_GetUSBId(USB_BULK_HANDLE hDevice,

U16 * pVendorId,

U16 * pProductId);

Parameters

Parameter Description

hDevice Handle to the opened device.

pVendorId Pointer to a variable that receives the Vendor ID.

pProductId Pointer to a variable that receives the Product ID.

147 CHAPTER 5 Host API

5.5.5.5 USBBULK_GetProductName()

Description

Retrieves the device/product name if available.

Prototype

int USBBULK_GetProductName(USB_BULK_HANDLE hDevice,

char * sProductName,

unsigned BufferSize);

Parameters

Parameter Description

hDevice Handle to the opened device.

sProductName Pointer to a buffer that should receive the string.

BufferSize Size of the buffer, given in bytes.

Return value

= 0 Error, product name not available or buffer to small.

≠ 0 Success, product name stored in buffer pointed by sProductName as 0-terminat-

ed string.

148 CHAPTER 5 Host API

5.5.5.6 USBBULK_GetVendorName()

Description

Retrieves the vendor name of an opened USBBULK device.

Prototype

int USBBULK_GetVendorName(USB_BULK_HANDLE hDevice,

char * sVendorName,

unsigned BufferSize);

Parameters

Parameter Description

hDevice Handle to the opened device.

sVendorName Pointer to a buffer that should receive the string.

BufferSize Size of the buffer, given in bytes.

Return value

= 0 Error, bad handle.

≠ 0 Success, vendor name stored in buffer pointed by sVendorName as 0-terminated

string.

149 CHAPTER 5 Host API

5.5.5.7 USBBULK_GetSN()

Description

Retrieves the USB serial number as a string which was sent by the device during the enu-

meration.

Prototype

int USBBULK_GetSN(USB_BULK_HANDLE hDevice,

U8 * pBuffer,

unsigned BuffSize);

Parameters

Parameter Description

hDevice Handle to the opened device.

pBuffer Pointer to a buffer which shall receive the serial number of

the device.

BuffSize Size of the buffer in bytes.

Return value

= 0 Operation failed. Either an invalid handle was used or the serial number is not

available.

≠ 0 The operation was successful.

Additional information

If the function succeeds, the buffer pointed by pBuffer contains the serial number of the

device as 0-terminated string. If BuffSize is too small, the serial number is truncated.

150 CHAPTER 5 Host API

5.5.5.8 USBBULK_GetConfigDescriptor()

Description

Gets the received target USB configuration descriptor of a specified device.

Prototype

int USBBULK_GetConfigDescriptor(USB_BULK_HANDLE hDevice,

void * pBuffer,

int Size);

Parameters

Parameter Description

hDevice Handle to the opened device.

pBuffer Pointer to the buffer that shall store the descriptor.

Size Size of the buffer, given in bytes.

Return value

≠ 0 Size of the returned USB configuration descriptor (Success).

= 0 Operation failed. Either an invalid handle was used or the buffer that shall store

the config descriptor is too small.

Chapter 6

Mass Storage Device Class

(MSD)

This chapter gives a general overview of the MSD class and describes how to get the MSD

component running on the target.

152 CHAPTER 6 Overview

6.1 Overview

The Mass Storage Device (MSD) is a USB class protocol defined by the USB Implementers

Forum. The class itself is used to access one or more storage devices such as flash drives

or memory sticks.

As the USB mass storage device class is well standardized, every major operating system

such as Microsoft Windows (after Windows 2000), Apple OS X, Linux and many more sup-

port it. So therefore an installation of a custom host USB driver is normally not necessary.

emUSB-Device-MSD comes as a whole packet and contains the following:

• Generic USB handling

• MSD device class implementation, including support for direct disk and CD-ROM mode

(CD-ROM access is a separate component)

• Several storage drivers for handling different devices

• Example applications

153 CHAPTER 6 MSD Configuration

6.2 MSD Configuration

6.2.1 Initial configuration

To get emUSB-Device-MSD up and running as well as doing an initial test, the configuration

as it is delivered should not be modified.

6.2.2 Final configuration

The configuration must only be modified, when emUSB-Device is deployed in your final

product. Refer to emUSB-Device Configuration on page 41 for detailed information about

the generic information functions which must be adapted.

In order to comply with the Mass Storage Device Bootability specification, the serial number

provided by the function USBD_SetDeviceInfo() must be a string with at least 12 charac-

ters, where each character is a hexadecimal digit (’0’ through ’9’ or ’A’ through ’F’).

6.2.3 MSD class specific configuration functions

Beside the generic emUSB-Device configuration functions (emUSB-Device Configuration on

page 41), the following should be adapted before the emUSB-Device MSD component is

used in a final product. Example implementations are supplied in the MSD example appli-

cation USB_MSD_FS_Start.c, located in the Application directory of emUSB-Device.

Each logical unit (storage) which is added to the MSD component has it’s own set of name

and id values which is supplied when the logical unit is first added through USBD_MSD_Ad-

dUnit()

Example

static const USB_MSD_LUN_INFO _Lun0Info = {

"Vendor", // MSD VendorName

"MSD Volume", // MSD ProductName

"1.00", // MSD ProductVer

"134657890" // MSD SerialNo

};

...

InstData.pLunInfo = &_Lun0Info;

...

USB_MSD_AddUnit(&InstData);

6.2.4 Running the example application

The directory Application contains example applications that can be used with emUSB-

Device and the MSD component. To test the emUSB-Device-MSD component, build and

download the application of choice into the target. Remove the USB connection and recon-

nect the target to the host. The target will enumerate and can be accessed via a file browser.

154 CHAPTER 6 MSD Configuration

6.2.4.1 MSD_Start_StorageRAM.c in detail

The main part of the example application USB_MSD_Start_StorageRAM.c is implemented

in a single task called MainTask().

/* MainTask() - excerpt from USB_MSD_Start_StorageRAM.c */

void MainTask(void);

void MainTask(void) {

USBD_Init();

_AddMSD();

USBD_Start();

while (1) {

while ((USBD_GetState() & (USB_STAT_CONFIGURED | USB_STAT_SUSPENDED))

!= USB_STAT_CONFIGURED) {

BSP_ToggleLED(0);

USB_OS_Delay(50);

}

BSP_SetLED(0);

USBD_MSD_Task();

}

The first step is to initialize the USB core stack using USBD_Init(). The function _AddMSD()

configures all required endpoints and assigns the used storage medium to the MSD com-

ponent.

/* _AddMSD() - excerpt from MSD_Start_StorageRAM.c */

static void _AddMSD(void) {

static U8 _abOutBuffer[USB_HS_BULK_MAX_PACKET_SIZE];

USB_MSD_INIT_DATA InitData;

USB_MSD_INST_DATA InstData;

InitData.EPIn = USBD_AddEP(1, USB_TRANSFER_TYPE_BULK,

USB_HS_BULK_MAX_PACKET_SIZE, NULL, 0);

InitData.EPOut = USBD_AddEP(0, USB_TRANSFER_TYPE_BULK,

USB_HS_BULK_MAX_PACKET_SIZE,

_abOutBuffer, sizeof(_abOutBuffer));

USBD_MSD_Add(&InitData);

// Add logical unit 0: RAM drive

memset(&InstData, 0, sizeof(InstData));

InstData.pAPI = &USB_MSD_StorageRAM;

InstData.DriverData.pStart = (void*)MSD_RAM_ADDR;

InstData.DriverData.NumSectors = MSD_RAM_NUM_SECTORS;

InstData.DriverData.SectorSize = MSD_RAM_SECTOR_SIZE;

InstData.pLunInfo = &_Lun0Info;

USBD_MSD_AddUnit(&InstData);

}

The example application uses a RAM disk as storage medium.

The example RAM disk has a size of 23 kB (46 sectors with a sector size of 512 bytes). You

can increase the size of the RAM disk by modifying the macros MSD_RAM_NUM_SECTORS and

MSD_RAM_SECTOR_SIZE (in multiples of 512), but the size must be at least 23 kB otherwise

a Windows host cannot format the disk.

/* AddMSD() - excerpt from MSD_Start_StorageRAM.c */

#define MSD_RAM_NUM_SECTORS 46

#define MSD_RAM_SECTOR_SIZE 512

155 CHAPTER 6 Target API

6.3 Target API

Function Description

API functions

USBD_MSD_Add() Adds an MSD-class interface to the USB

stack.

USBD_MSD_AddUnit() Adds a mass storage device to emUSB-De-

vice-MSD.

USBD_MSD_AddCDRom() Adds a CD-ROM device to emUSB-De-

vice-MSD.

USBD_MSD_SetPreventAllowRemoval-

Hook() Sets a callback function to prevent/allow

removal of storage medium.

USBD_MSD_SetPreventAllowRemoval-

HookEx() Sets a callback function to prevent/allow

removal of storage medium.

USBD_MSD_SetReadWriteHook() Sets a callback function which gives in-

formation about the read and write block-

wise.

USBD_MSD_Task() Task that handles the MSD-specific proto-

col.

USBD_MSD_SetStartStopUnitHook() Sets the callback when the command

StartStopUnit is called.

Extended API functions

USBD_MSD_Connect() Connects the storage medium to the MSD.

USBD_MSD_Disconnect() Disconnects the storage medium from the

MSD.

USBD_MSD_RequestDisconnect() Sets the DisconnectRequest flag.

USBD_MSD_RequestRefresh() Performs a disconnect (optional), a detach

and optionally a re-attach, to inform host

that volume contents has changed.

USBD_MSD_UpdateWriteProtect() This functions updates the write protect

status of the storage medium.

USBD_MSD_WaitForDisconnection() Waits for disconnection while time out is

not reached.

Data structures

USB_MSD_INIT_DATA emUSB-Device-MSD initialization structure

that is required when adding an MSD inter-

face.

USB_MSD_INFO emUSB-Device-MSD storage interface.

USB_MSD_INST_DATA USB-MSD initialization structure that is re-

quired when adding an MSD interface.

PREVENT_ALLOW_REMOVAL_HOOK Callback function to prevent/allow removal

of storage medium.

PREVENT_ALLOW_REMOVAL_HOOK_EX Callback function to prevent/allow removal

of storage medium.

READ_WRITE_HOOK Callback function which is called with every

read/write access to the storage medium.

USB_MSD_INST_DATA_DRIVER USB-MSD initialization structure that is re-

quired when adding an MSD interface.

USB_MSD_STORAGE_API USB-MSD initialization structure that is re-

quired when adding an MSD interface.

156 CHAPTER 6 Target API

Function Description

START_STOP_UNIT_HOOK Callback function which is called when a

START STOP UNIT SCSI command is re-

ceived.

157 CHAPTER 6 Target API

6.3.1 API functions

6.3.1.1 USBD_MSD_Add()

Description

Adds an MSD-class interface to the USB stack.

Prototype

void USBD_MSD_Add(const USB_MSD_INIT_DATA * pInitData);

Parameters

Parameter Description

pInitData Pointer to a USB_MSD_INIT_DATA structure.

Additional information

After the initialization of general emUSB-Device, this is the first function that needs to be

called when an MSD interface is used with emUSB-Device. The structure USB_MSD_INIT_DA-

TA must be initialized before USBD_MSD_Add() is called.

158 CHAPTER 6 Target API

6.3.1.2 USBD_MSD_AddUnit()

Description

Adds a mass storage device to emUSB-Device-MSD.

Prototype

void USBD_MSD_AddUnit(const USB_MSD_INST_DATA * pInstData);

Parameters

Parameter Description

pInstData Pointer to a USB_MSD_INST_DATA structure containing the in-

formation of the added storage device.

Additional information

It is necessary to call this function immediately after USBD_MSD_Add(). It will then add an

R/W storage device to emUSB-Device-MSD. The structure USB_MSD_INST_DATA must be

initialized before calling USBD_MSD_AddUnit().

159 CHAPTER 6 Target API

6.3.1.3 USBD_MSD_AddCDRom()

Description

Adds a CD-ROM device to emUSB-Device-MSD.

Prototype

void USBD_MSD_AddCDRom(const USB_MSD_INST_DATA * pInstData);

Parameters

Parameter Description

pInstData Pointer to a USB_MSD_INST_DATA structure containing the in-

formation of the added storage device.

Additional information

Similar to USBD_MSD_AddUnit(), this function should be called after USBD_MSD_Add(). The

structure USB_MSD_INST_DATA must be initialized before USBD_MSD_AddCDRom() is called.

160 CHAPTER 6 Target API

6.3.1.4 USBD_MSD_SetPreventAllowRemovalHook()

Description

Sets a callback function to prevent/allow removal of storage medium.

Prototype

void USBD_MSD_SetPreventAllowRemovalHook

(U8 Lun,

PREVENT_ALLOW_REMOVAL_HOOK * pfOnPreventAllowRemoval);

Parameters

Parameter Description

Lun Logical Unit Number. Using only one storage medium, this

parameter is 0.

pfOnPreventAllowRe-

moval Callback to the callback that shall be called.

Additional information

The callback is called within the MSD task context. The callback must not block.

161 CHAPTER 6 Target API

6.3.1.5 USBD_MSD_SetPreventAllowRemovalHookEx()

Description

Sets a callback function to prevent/allow removal of storage medium.

Prototype

void USBD_MSD_SetPreventAllowRemovalHookEx

(U8 Lun,

PREVENT_ALLOW_REMOVAL_HOOK_EX * pfOnPreventAllowRemovalEx);

Parameters

Parameter Description

Lun Zero-based index for the unit number. Using only one stor-

age medium, this parameter is 0.

pfOnPreventAllowRe-

movalEx

Callback to the callback that shall be called. For detailed in-

formation about the function pointer, refer to PREVENT_AL-

LOW_REMOVAL_HOOK_EX.

Additional information

The callback is called within the MSD task context. The callback must not block.

162 CHAPTER 6 Target API

6.3.1.6 USBD_MSD_SetReadWriteHook()

Description

Sets a callback function which gives information about the read and write blockwise. oper-

ations to the storage medium.

Prototype

void USBD_MSD_SetReadWriteHook(U8 Lun,

READ_WRITE_HOOK * pfOnReadWrite);

Parameters

Parameter Description

Lun Zero-based index for the unit number. Using only one stor-

age medium, this parameter is 0.

pfOnReadWrite Pointer to the callback function that shall be called.

163 CHAPTER 6 Target API

6.3.1.7 USBD_MSD_Task()

Description

Task that handles the MSD-specific protocol.

Prototype

void USBD_MSD_Task(void);

Additional information

After the USB device has been successfully enumerated and configured, the USB-

D_MSD_Task() should be called. When the device is detached or is suspended, USB-

D_MSD_Task() will return.

164 CHAPTER 6 Target API

6.3.1.8 USBD_MSD_SetStartStopUnitHook()

Description

Sets the callback when the command StartStopUnit is called.

Prototype

void USBD_MSD_SetStartStopUnitHook(U8 Lun,

START_STOP_UNIT_HOOK * pfOnStartStopUnit);

Parameters

Parameter Description

Lun Zero-based index for the unit number. Using only one stor-

age medium, this parameter is 0.

pfOnStartStopUnit Callback to the callback that shall be called. For detailed

information about the function pointer, refer to START_S-

TOP_UNIT_HOOK.

165 CHAPTER 6 Target API

6.3.2 Extended API functions

6.3.2.1 USBD_MSD_Connect()

Description

Connects the storage medium to the MSD.

Prototype

void USBD_MSD_Connect(U8 Lun);

Parameters

Parameter Description

Lun Zero-based index for the unit number. Using only one stor-

age medium, this parameter is 0.

Additional information

The storage medium is initially always connected to the MSD component. This function is

normally used after the storage medium was disconnected via USBD_MSD_Disconnect()

to carry out file system operations on the device application side. The stack connects the

storage medium next time when the HOST requests the status of the storage medium.

166 CHAPTER 6 Target API

6.3.2.2 USBD_MSD_Disconnect()

Description

Disconnects the storage medium from the MSD.

Prototype

void USBD_MSD_Disconnect(U8 Lun);

Parameters

Parameter Description

Lun Zero-based index for the unit number. Using only one stor-

age medium, this parameter is 0.

Additional information

This function will force the storage medium to be disconnected. The host will be informed

that the medium is not present. In order to reconnect the device to the host, the func-

tion USBD_MSD_Connect() shall be used. See USBD_MSD_RequestDisconnect() and USB-

D_MSD_WaitForDisconnection() for a graceful disconnection method.

167 CHAPTER 6 Target API

6.3.2.3 USBD_MSD_RequestDisconnect()

Description

Sets the DisconnectRequest flag.

Prototype

void USBD_MSD_RequestDisconnect(U8 Lun);

Parameters

Parameter Description

Lun Zero-based index for the unit number. Using only one stor-

age medium, this parameter is 0.

Additional information

This function sets the disconnect flag for the storage medium. As soon as the next MSD

command is sent to the device, the host will be informed that the device is currently not

available. To reconnect the storage medium, USBD_MSD_Connect() shall be called.

Notes

If the HOST tries to access the storage medium while this flag is set to 1, the status of the

storage medium changes to disconnected.

168 CHAPTER 6 Target API

6.3.2.4 USBD_MSD_RequestRefresh()

Description

Performs a disconnect (optional), a detach and optionally a re-attach, to inform host that

volume contents has changed.

Prototype

void USBD_MSD_RequestRefresh(U8 Lun,

U32 Flags);

Parameters

Parameter Description

Lun Zero-based index for the unit number. Using only one stor-

age medium, this parameter is 0.

Flags

Request flags, a bit-ored combination of the following flags:

•USB_MSD_TRY_DISCONNECT - Try a medium disconnect be-

fore doing a USB detach.

•USB_MSD_RE_ATTACH - Automatically re-attach after detach

has been done.

Additional information

If the flag USB_MSD_TRY_DISCONNECT is given, the function sets the disconnect flag for the

storage medium. As soon as the next MSD command is sent to the device, the host will be

informed that the device is currently not available. If the host acknowledges the disconnect,

the medium is reconnected and the function USBD_MSD_Task() will return.

If the flag USB_MSD_TRY_DISCONNECT is not set or the host ignores the disconnection of the

medium, the USB device is detached from the host (using USBD_Stop()).

If the flag USB_MSD_RE_ATTACH is set, the device is re-attached after some delay us-

ing USBD_Start(). Then the unction USBD_MSD_Task() will return. The function USB-

D_MSD_RequestRefresh() returns immediately while the procedure is executed in the USB-

D_MSD_Task().

Returning of the function USBD_MSD_Task() allows the application to reinitialize the vol-

ume (or calling USBD_Start(), if USB_MSD_RE_ATTACH was not set) before calling USB-

D_MSD_Task() again.

Detaching the USB device not only affects the specified volume (Lun) but all volumes of

the device.

169 CHAPTER 6 Target API

6.3.2.5 USBD_MSD_UpdateWriteProtect()

Description

This functions updates the write protect status of the storage medium.

Prototype

void USBD_MSD_UpdateWriteProtect(U8 Lun,

U8 IsWriteProtected);

Parameters

Parameter Description

Lun Zero-based index for the unit number. Using only one stor-

age medium, this parameter is 0.

IsWriteProtected Set the write protect flag:

1 - Medium is write-protected.

0 - Medium is NOT write-protected.

Additional information

This functions updates the write protect status of the storage medium. Please make sure

that this function is called when the LUN is disconnected from the host, otherwise the

WriteProtected flag is normally not recognized.

170 CHAPTER 6 Target API

6.3.2.6 USBD_MSD_WaitForDisconnection()

Description

Waits for disconnection while time out is not reached.

Prototype

int USBD_MSD_WaitForDisconnection(U8 Lun,

U32 TimeOut);

Parameters

Parameter Description

Lun Zero-based index for the unit number. Using only one stor-

age medium, this parameter is 0.

TimeOut Timeout give in ms. How long should this function wait, until

it stops waiting.

Return value

0 Error - Time out reached. Device not disconnected.

1 Success - Device disconnected.

Additional information

After triggering the disconnection via USBD_MSD_RequestDisconnect() the stack discon-

nects the storage medium as soon as the host requests the status of the storage medium.

Win2k does not periodically check the status of a USB MSD. Therefore, the timeout is re-

quired to leave the loop. The return value can be used to decide if the disconnection should

be forced. In this case, USBD_MSD_Disconnect() shall be called.

171 CHAPTER 6 Target API

6.3.3 Data structures

6.3.3.1 USB_MSD_INIT_DATA

Description

emUSB-Device-MSD initialization structure that is required when adding an MSD interface.

Type definition

typedef struct {

U8 EPIn;

U8 EPOut;

U8 InterfaceNum;

} USB_MSD_INIT_DATA;

Structure members

Member Description

EPIn Endpoint for sending data to the host.

EPOut Endpoint for receiving data from the host.

InterfaceNum Interface number. This member is normally internally used,

so therefore the value shall be set to 0.

Additional information

This structure holds the endpoints that should be used with the MSD interface. Refer to

USBD_AddDriver() for more information about how to add an endpoint.

172 CHAPTER 6 Target API

6.3.3.2 USB_MSD_INFO

Description

emUSB-Device-MSD storage interface.

Type definition

typedef struct {

U32 NumSectors;

U16 SectorSize;

} USB_MSD_INFO;

Structure members

Member Description

NumSectors Number of available sectors.

SectorSize Size of one sector.

173 CHAPTER 6 Target API

6.3.3.3 USB_MSD_INST_DATA

Description

USB-MSD initialization structure that is required when adding an MSD interface.

Type definition

typedef struct {

const USB_MSD_STORAGE_API * pAPI;

USB_MSD_INST_DATA_DRIVER DriverData;

U8 DeviceType;

U8 IsPresent;

USB_MSD_HANDLE_CMD * pfHandleCmd;

U8 IsWriteProtected;

const USB_MSD_LUN_INFO * pLunInfo;

} USB_MSD_INST_DATA;

Structure members

Member Description

pAPI Pointer to a structure that holds the storage device driver

API.

DriverData Driver data that are passed to the storage driver. Refer to

USB_MSD_INST_DATA_DRIVER for detailed information about

how to initialize this structure.

DeviceType Determines the type of the device:

0: Direct access block device

5: CD/DVD

IsPresent Determines if the medium is storage is present. For non-re-

movable devices always 1.

pfHandleCmd Optional pointer to a callback function which handles SCSI

commands.

IsWriteProtected Specifies whether the storage medium shall be write-pro-

tected.

pLunInfo Pointer to a USB_MSD_LUN_INFO structure. Filling this struc-

ture is mandatory for each LUN.

Additional information

All non-optional members of this structure need to be initialized correctly, except Device-

Type and pfHandleCmd because it is done by the functions USBD_MSD_AddUnit() or USB-

D_MSD_AddCDROM().

174 CHAPTER 6 Target API

6.3.3.4 USB_MSD_LUN_INFO

Description

Structure that is used when adding a logical volume to emUSB-Device-MSD.

Type definition

typedef struct {

const char * pVendorName;

const char * pProductName;

const char * pProductVer;

const char * pSerialNo;

} USB_MSD_LUN_INFO;

Structure members

Member Description

pVendorName Vendor name of the mass storage device. The string should

be no longer than 8 bytes.

pProductName Product name of the mass storage device. The product name

string should be no longer than 16 bytes.

pProductVer Product version number of the mass storage device. The

product version string should be no longer than 4 bytes.

pSerialNo Product serial number of the mass storage device. The seri-

al number string must be exactly 12 bytes, in order to satis-

fy the USB bootability specification requirements.

Additional information

The setting of these values is mandatory, if these values remain NULL at initialisation

emUSB-Device will report a panic error in debug builds (USB_PANIC).

175 CHAPTER 6 Target API

6.3.3.5 PREVENT_ALLOW_REMOVAL_HOOK

Description

Callback function to prevent/allow removal of storage medium. See USBD_MSD_SetPreven-

tAllowRemovalHook().

Type definition

typedef void (PREVENT_ALLOW_REMOVAL_HOOK)(U8 PreventRemoval);

Parameters

Parameter Description

PreventRemoval Show whether the device shall be locked or not.

• 0 - The device shall be removable.

• 1 - The device shall be locked.

Additional information

Most OSes call the prevent/allow removal before any write operation. This callback will be

called for all LUNs that are available on the host.

176 CHAPTER 6 Target API

6.3.3.6 PREVENT_ALLOW_REMOVAL_HOOK_EX

Description

Callback function to prevent/allow removal of storage medium. See USBD_MSD_SetPreven-

tAllowRemovalHookEx().

Type definition

typedef void (PREVENT_ALLOW_REMOVAL_HOOK_EX)(U8 Lun,

U8 PreventRemoval);

Parameters

Parameter Description

Lun Logical Unit Number.

PreventRemoval Show whether the device shall be locked or not.

• 0 - The device shall be removable.

• 1 - The device shall be locked.

Additional information

Most OSes call the prevent/allow removal before any write operation.

177 CHAPTER 6 Target API

6.3.3.7 READ_WRITE_HOOK

Description

Callback function which is called with every read/write access to the storage medium.

Type definition

typedef void (READ_WRITE_HOOK)(U8 Lun,

U8 IsRead,

U8 OnOff,

U32 StartLBA,

U32 NumBlocks);

Parameters

Parameter Description

Lun Specifies the logical unit number which was accessed

through read or write.

IsRead Specifies whether a read or a write access was used:

• 1 : read,

• 0 : write.

OnOff States whether the read or write request has been initialized

(1) or whether it is complete (0).

StartLBA The first Logical Block Address accessed by the transfer.

NumBlocks The number of blocks accessed by the transfer, starting from

the StartLBA.

178 CHAPTER 6 Target API

6.3.3.8 USB_MSD_INST_DATA_DRIVER

Description

USB-MSD initialization structure that is required when adding an MSD interface.

Type definition

typedef struct {

void * pStart;

U32 StartSector;

U32 NumSectors;

U16 SectorSize;

void * pSectorBuffer;

unsigned NumBytes4Buffer;

U8 NumBuffers;

} USB_MSD_INST_DATA_DRIVER;

Structure members

Member Description

pStart A pointer defining the start address

StartSector The start sector that is used for the driver.

NumSectors The available number of sectors available for the driver.

SectorSize The sector size that should be used by the driver.

pSectorBuffer Pointer to an application provided buffer to be used as tem-

porary buffer for storing the sector data.

NumBytes4Buffer Size of the application provided buffer.

NumBuffers Number of buffer that are available. This is only used when

using the MT storage layer.

Additional information

This structure is passed to the storage driver. Therefore, the member of this structure can

depend on the driver that is used. For the storage driver that are shipped with this software

the members of USB_MSD_INST_DATA_DRIVER have the following meaning:

USB_MSD_StorageRAM:

Member Description

pStart A pointer defining the start address of the RAM disk.

StartSector This member is ignored.

NumSectors The available number of sectors available for the RAM disk.

SectorSize The sector size that should be used by the driver.

USB_MSD_StorageByName:

Member Description

pStart Pointer to a string holding the name of the volumes that

shall be used, for example “nand:” “mmc:1:”

StartSector Specifies the start sector.

NumSectors Number of sector that shall be used.

SectorSize This member is ignored.

pSectorBuffer Pointer to an application provided buffer to be used as tem-

porary buffer for storing the sector data

NumBytes4Buffer Size of the buffer provided by the application. Please make

sure that the buffer can at least 3 sectors otherwise, pSec-

179 CHAPTER 6 Target API

Member Description

torBuffer and NumBytes4Buffer are ignored and an inter-

nal sector buffer is used. This sector-buffer is then allocated

by using the FS-Storage-Layer functions.

180 CHAPTER 6 Target API

6.3.3.9 USB_MSD_STORAGE_API

Description

USB-MSD initialization structure that is required when adding an MSD interface.

Type definition

typedef struct {

USB_MSD_STORAGE_INIT * pfInit;

USB_MSD_STORAGE_GETINFO * pfGetInfo;

USB_MSD_STORAGE_GETREADBUFFER * pfGetReadBuffer;

USB_MSD_STORAGE_READ * pfRead;

USB_MSD_STORAGE_GETWRITEBUFFER * pfGetWriteBuffer;

USB_MSD_STORAGE_WRITE * pfWrite;

USB_MSD_STORAGE_MEDIUMISPRESENT * pfMediumIsPresent;

USB_MSD_STORAGE_DEINIT * pfDeInit;

} USB_MSD_STORAGE_API;

Structure members

Member Description

pfInit Initializes the storage medium.

pfGetInfo Retrieves storage medium information such as sector size

and number of sectors available.

pfGetReadBuffer Prepares read function and returns a pointer to a buffer that

is used by the storage driver.

pfRead Reads one or multiple sectors from the storage medium.

pfGetWriteBuffer Prepares write function and returns a pointer to a buffer that

is used by the storage driver.

pfWrite Writes one or more sectors to the storage medium.

pfMediumIsPresent Checks if medium is present.

pfDeInit De-initializes the storage medium.

Additional information

USB_MSD_STORAGE_API is used to retrieve information from the storage device driver or

access data that needs to be read or written. Detailed information can be found in MSD

Storage Driver on page 182.

181 CHAPTER 6 Target API

6.3.3.10 START_STOP_UNIT_HOOK

Description

Callback function which is called when a START STOP UNIT SCSI command is received.

Type definition

typedef void (START_STOP_UNIT_HOOK)(U8 Lun,

U8 StartLoadEject);

Parameters

Parameter Description

Lun Specifies the logical unit number.

StartLoadEject

Specifies which operation is executed by the host:

• 0 : Stop disk

• 1 : Start disk and make ready for access

• 2 : Eject disk if permitted

• 3 : Load, start and make disk ready.

182 CHAPTER 6 MSD Storage Driver

6.4 MSD Storage Driver

6.4.1 General information

The storage interface is handled through an API-table, which contains all relevant functions

necessary for read/write operations and initialization. Its implementation handles the de-

tails of how data is actually read from or written to memory. Additionally, MSD knows two

different media types:

• Direct media access, for example RAM-Disk, NAND flash, MMC/SD cards etc.

• CD-ROM emulation.

6.4.1.1 Supported storage types

The supported storage types include:

• RAM, directly connected to the processor via the address bus.

• External flash memory, e.g. SD cards.

• Mechanical drives, for example CD-ROM. This is essentially an ATA/SCSI to USB bridge.

6.4.1.2 Storage drivers supplied with this release

This release comes with the following drivers:

•USB_MSD_StorageRAM: A RAM driver which should work with almost any device.

•USB_MSD_StorageByIndex: A storage driver that uses the storage layer (logical block

layer) of emFile to access the device.

•USB_MSD_StorageByName: A storage driver that uses the storage layer (logical block

layer) of emFile to access the device.

6.4.2 Interface function list

As described above, access to a storage medium is realized through an API-function table

(USB_MSD_STORAGE_API). The storage functions are declared in USB_MSD.h.

183 CHAPTER 6 MSD Storage Driver

6.4.3 USB_MSD_STORAGE_API in detail

6.4.3.1 USB_MSD_STORAGE_INIT

Description

Initializes the storage medium.

Type definition

typedef void (USB_MSD_STORAGE_INIT)( U8 Lun,

const USB_MSD_INST_DATA_DRIVER * pDriverData);

Parameters

Parameter Description

Lun Logical unit number. Specifies for which drive the function is

called.

pDriverData

Pointer to a USB_MSD_INST_DATA_DRIVER structure that con-

tains all information that is necessary for the driver initializa-

tion. Refer to USB_MSD_INST_DATA_DRIVER structure for de-

tailed information.

184 CHAPTER 6 MSD Storage Driver

6.4.3.2 USB_MSD_STORAGE_GETINFO

Description

Retrieves storage medium information such as sector size and number of sectors available.

Type definition

typedef void (USB_MSD_STORAGE_GETINFO)(U8 Lun,

USB_MSD_INFO * pInfo);

Parameters

Parameter Description

Lun Logical unit number. Specifies for which drive the function is

called.

pInfo Pointer to a USB_MSD_INFO structure. For detailed in-

formation about the USB_MSD_INFO structure, refer to

USB_MSD_INFO.

185 CHAPTER 6 MSD Storage Driver

6.4.3.3 USB_MSD_STORAGE_GETREADBUFFER

Description

Prepares the read function and returns a pointer to a buffer that is used by the storage

driver.

Type definition

typedef U32 (USB_MSD_STORAGE_GETREADBUFFER)(U8 Lun,

U32 SectorIndex,

void ** ppData,

U32 NumSectors);

Parameters

Parameter Description

Lun Logical unit number. Specifies for which drive the function is

called.

SectorIndex Specifies the start sector for the read operation.

ppData Pointer to a pointer to store the read buffer address of the

driver.

NumSectors Number of sectors to read.

Return value

Maximum number of consecutive sectors that can be read at once by the driver.

186 CHAPTER 6 MSD Storage Driver

6.4.3.4 USB_MSD_STORAGE_READ

Description

Reads one or multiple consecutive sectors from the storage medium.

Type definition

typedef char (USB_MSD_STORAGE_READ)(U8 Lun,

U32 SectorIndex,

void * pData,

U32 NumSectors);

Parameters

Parameter Description

Lun Logical unit number. Specifies for which drive the function is

called.

SectorIndex Specifies the start sector from where the read operation is

started.

pData Pointer to buffer to store the read data.

NumSectors Number of sectors to read.

Return value

= 0 Success.

≠ 0 Failed.

187 CHAPTER 6 MSD Storage Driver

6.4.3.5 USB_MSD_STORAGE_GETWRITEBUFFER

Description

Prepares the write function and returns a pointer to a buffer that is used by the storage

driver.

Type definition

typedef U32 (USB_MSD_STORAGE_GETWRITEBUFFER)(U8 Lun,

U32 SectorIndex,

void ** ppData,

U32 NumSectors);

Parameters

Parameter Description

Lun Logical unit number. Specifies for which drive the function is

called.

SectorIndex Specifies the start sector for the write operation.

ppData Pointer to a pointer to store the write buffer address of the

driver.

NumSectors Number of sectors to write.

Return value

Maximum number of consecutive sectors that can be written into the buffer.

188 CHAPTER 6 MSD Storage Driver

6.4.3.6 USB_MSD_STORAGE_WRITE

Description

Writes one or more consecutive sectors to the storage medium.

Type definition

typedef char (USB_MSD_STORAGE_WRITE)( U8 Lun,

U32 SectorIndex,

const void * pData,

U32 NumSectors);

Parameters

Parameter Description

Lun Logical unit number. Specifies for which drive the function is

called.

SectorIndex Specifies the start sector for the write operation.

pData Pointer to data to be written to the storage medium.

NumSectors Number of sectors to write.

Return value

= 0 Success.

≠ 0 Failed.

189 CHAPTER 6 MSD Storage Driver

6.4.3.7 USB_MSD_STORAGE_MEDIUMISPRESENT

Description

Checks if medium is present.

Type definition

typedef char (USB_MSD_STORAGE_MEDIUMISPRESENT)(U8 Lun);

Parameters

Parameter Description

Lun Logical unit number. Specifies for which drive the function is

called.

Return value

1 Medium is present.

0 Medium is not present.

190 CHAPTER 6 MSD Storage Driver

6.4.3.8 USB_MSD_STORAGE_DEINIT

Description

De-initializes the storage medium.

Type definition

typedef void (USB_MSD_STORAGE_DEINIT)(U8 Lun);

Parameters

Parameter Description

Lun Logical unit number. Specifies for which drive the function is

called.

Chapter 7

Smart Mass Storage

Component (SmartMSD)

This chapter gives a general overview of the SmartMSD component and describes how to

get the SmartMSD running on the target.

192 CHAPTER 7 Overview

7.1 Overview

The SmartMSD component allows to easily stream files to and from USB devices. Once the

USB device is connected to the host, files can be read or written to the application without

the need for dedicated storage memory.

This makes the software very flexible: it can be used for various types of applications and

purposes, with no additional software or drivers necessary on the host side.

The SmartMSD software analyzes what operation is performed by the host and passes

this to the application layer of the embedded target, which then performs the appropriate

action. A simple drag and drop is all it takes to initialize this process, which is supported

by a unique active file technology.

Smart MSD can access all data which has been created prior to the device being attached

to the host, live data cannot be provided.

SmartMSD allows to use the storage device in a virtual manner, which means data does

not need to be stored on a physical medium.

The storage device will be shown on the host as a FAT formated volume with a configurable

size and a configurable file list.

With the help of that virtual function, the target device can be used for different applications

by simply dragging and dropping files to and from the storage medium:

• Firmware update application.

• Configuration updater.

• File system firewall - protect the target’s filesystem from being manipulated by the host.

The component itself is based on MSD class and thus can be used on virtually any OS such

as any Windows, macOS or any Linux distribution (including Android) which supports MSD,

without installing any third party tools.

193 CHAPTER 7 Configuration

7.2 Configuration

7.2.1 Initial configuration

To get emUSB-Device-SmartMSD up and running as well as doing an initial test, the con-

figuration as is delivered should not be modified.

7.2.2 Final configuration

The configuration must only be modified if emUSB-Device is deployed in your final product.

Refer to emUSB-Device Configuration on page 41 for detailed information about the generic

information functions which must be adapted.

7.2.3 Class specific configuration functions

For basic configuration please refer to the MSD chapter MSD class specific configuration

functions on page 153. In addition to the MSD configuration functions described there the

following SmartMSD functions are available.

Function Description

emUSB-Device-SmartMSD configuration functions

USB_SMSD_X_Config() Configures the SmartMSD component.

194 CHAPTER 7 Configuration

7.2.3.1 USB_SMSD_X_Config()

Description

Main user configuration function of the SmartMSD component. This function is provided

by the user.

Prototype

void USB_SMSD_X_Config(void);

Example

void USB_SMSD_X_Config(void) {

// String information used when inquiring the volume.

static const USB_MSD_LUN_INFO _LunInfo = {

"Vendor", // MSD VendorName

"MSD Volume", // MSD ProductName

"1.00", // MSD ProductVer

"134657890" // MSD SerialNo

};

// Global configuration

USBD_SMSD_AssignMemory(&_aMEMBuffer[0], sizeof(_aMEMBuffer));

// Setup LUN0

USBD_SMSD_SetNumSectors(0, 8000);

USBD_SMSD_SetSectorsPerCluster(0, 32); // Anywhere from 1...128, needs to be

2^x

USBD_SMSD_SetNumRootDirSectors(0, 2);

USBD_SMSD_SetUserAPI(0, &_UserFuncAPI);

USBD_SMSD_SetVolumeInfo(0, "Virt0.MSD", &_LunInfo); // Add volume ID

// Push const contents to the volume

USBD_SMSD_AddConstFiles(0, &_aConstFiles[0], COUNTOF(_aConstFiles));

}

Additional information

During the call of USBD_SMSD_Add() this user function is called in order to configure the

SmartMSD module according to the user’s preferences. In order to allow the user to config-

ure the volume it is necessary to provide either a memory block or memory allocation/free

callbacks to SmartMSD component.

7.2.4 Running the example application

The directory Application contains example applications that can be used with emUSB-

Device and the SmartMSD component. To test the SmartMSD component, build and down-

load the application of choice into the target. Remove the USB connection and reconnect

the target to the host. The target will enumerate and can be accessed via a file browser.

195 CHAPTER 7 Configuration

7.2.5 Calculation of RAM memory usage for SmartMSD

An application has to provide RAM memory in order to use SmartMSD either via a call to

the function USB_SmartMSD_AssignMemory() or by setting callback functions for memory

allocation. The amount of memory used can be calculated as follows:

For each volume:

Purpose Bytes used Minimum

Global volume information 128 128

Cluster info for predefined files added with USB_S-

martMSD_AddConstFiles() 2 (for each file) 0

I/O Buffer 512 512

Directory m * 512 512

FAT n * 512 512

Total - 1664

The number of files that can be stored on the volume depends on the size of the directory

which is configured using USB_SmartMSD_SetNumRootDirSectors():

Number of root directory sectors (m) Used memory

for directory

(bytes)

max. number of

files with short

(8.3) file name

1 512 15

2 1024 31

3 1536 47

4 2048 63

5 2560 79

6 3072 95

Files with long file names may occupy multiple entries in the directory, depending on the

actual length.

The number of FAT sectors (n) depends on the virtual size of the volume (configured using

USB_SmartMSD_SetNumSectors()) and the number of sectors per cluster:

Number of sectors Sectors per cluster Used memory

for FAT (bytes) approx. virtual

volume size (MB)

10880 32 512 5.4

21792 32 1024 10.8

32704 32 1536 16.3

43616 32 2048 21.7

54528 32 2560 27.2

65440 32 3072 32.7

76352 32 3584 38.1

87264 32 4096 43.6

98176 32 4608 49.0

109088 32 5120 54.5

120000 32 5632 59.9

130720 32 6144 65.3

43520 128 512 21.3

87168 128 1024 43.5

196 CHAPTER 7 Configuration

Number of sectors Sectors per cluster Used memory

for FAT (bytes) approx. virtual

volume size (MB)

130816 128 1536 65.3

174464 128 2048 87.1

218112 128 2560 108.9

261760 128 3072 130.8

305408 128 3584 152.6

349056 128 4096 174.4

392704 128 4608 196.2

436352 128 5120 218.1

480000 128 5632 239.9

522800 128 6144 261.3

There is no disadvantage of using the maximum possible number of sectors per cluster

(128).

In most cases the minimal configuration (FAT = 512 and directory = 512) should be suffi-

cient. It supports a small number of files with a total size of all files up to 21 MB. If more files

or bigger files are needed, the required parameters can be looked up in the tables above.

197 CHAPTER 7 Target API

7.3 Target API

Function Description

API functions

USBD_SMSD_Add() Create SmartMSD volumes and add MSD

interface to the device.

User supplied functions

USB_SMSD_X_Config() User supplied function that configures all

storages of the SMSD component.

Configuration functions

USBD_SMSD_AssignMemory() Assigns memory to the SmartMSD module.

USBD_SMSD_SetUserAPI() Sets the default user callbacks for the

SmartMSD component.

USBD_SMSD_SetNumRootDirSectors() Sets the number of sectors which should

be used for root directory entries.

USBD_SMSD_SetVolumeInfo() Sets the volume name for a specified LUN.

USBD_SMSD_AddConstFiles() Adds constant files to SmartMSD.

USBD_SMSD_SetNumSectors() Sets the number of sectors available on

the volume.

USBD_SMSD_SetSectorsPerCluster() Set number of sectors per cluster.

Data structures

USB_SMSD_CONST_FILE

This structure contains information about

a constant file which cannot be changed at

run time and should be shown inside the

SmartMSD volume (e.g.

USB_SMSD_USER_FUNC_API This structure contains the function point-

ers for user provided functions.

USB_SMSD_FILE_INFO Structure used in the read and write call-

backs.

USB_SMSD_DIR_ENTRY_SHORT Structure used to describe an entry with a

short file name.

Function definitions

USB_SMSD_ON_READ_FUNC Callback function prototype that is used

when calling the USBD_SMSD_SetUserAPI()

function.

USB_SMSD_ON_WRITE_FUNC Callback function prototype that is used

when calling the USBD_SMSD_SetUserAPI()

function.

USB_SMSD_MEM_ALLOC Function prototype that is used when

memory is being allocated by the Smart-

MSD module.

USB_SMSD_MEM_FREE Function prototype that is used when

memory is being freed by the SmartMSD

module.

198 CHAPTER 7 Target API

7.3.1 API functions

7.3.1.1 USBD_SMSD_Add()

Description

Create SmartMSD volumes and add MSD interface to the device.

Prototype

void USBD_SMSD_Add(void);

Additional information

After the initialization of emUSB-Device, this is the first function that needs to be called

when the SmartMSD component is used with emUSB-Device. During the call of the said

function the user function USB_SMSD_X_Config() is called in order to configure the storage

itself.

199 CHAPTER 7 Target API

7.3.1.2 USB_SMSD_X_Config()

Description

User supplied function that configures all storages of the SMSD component.

Prototype

void USB_SMSD_X_Config(void);

Additional information

This function is called automatically by USBD_SMSD_Add() in order to allow to configure the

storage volumes that SmartMSD should show after configuration.

Only the following functions must be called in this context:

Allowed functions with USB_X_SMSD_Config:

USBD_SMSD_AssignMemory()

USBD_SMSD_SetUserAPI()

USBD_SMSD_SetNumRootDirSectors()

USBD_SMSD_SetVolumeInfo()

USBD_SMSD_AddConstFiles()

USBD_SMSD_SetNumSectors()

USBD_SMSD_SetSectorsPerCluster()

200 CHAPTER 7 Target API

7.3.1.3 USBD_SMSD_AssignMemory()

Description

Assigns memory to the SmartMSD module.

Prototype

void USBD_SMSD_AssignMemory(U32 * p,

U32 NumBytes);

Parameters

Parameter Description

pPointer to the memory which should be dedicated to Smart-

MSD.

NumBytes Size of the memory block in bytes.

Additional information

See Calculation of RAM memory usage for SmartMSD on page 195.

201 CHAPTER 7 Target API

7.3.1.4 USBD_SMSD_SetUserAPI()

Description

Sets the default user callbacks for the SmartMSD component.

Prototype

void USBD_SMSD_SetUserAPI(const USB_SMSD_USER_FUNC_API * pUserFunc);

Parameters

Parameter Description

pUserFunc Pointer to a USB_SMSD_USER_FUNC_API structure which holds

the default function pointers for multiple functions.

Notes

(1) Must only be called from USB_SMSD_X_Config() during initialization phase

202 CHAPTER 7 Target API

7.3.1.5 USBD_SMSD_SetNumRootDirSectors()

Description

Sets the number of sectors which should be used for root directory entries.

Prototype

void USBD_SMSD_SetNumRootDirSectors(unsigned Lun,

unsigned NumRootDirSectors);

Parameters

Parameter Description

Lun Specifies the logical unit number.

NumRootDirSectors Number of sectors to be reserved for the root directory en-

tries.

Additional information

The number of sectors reserved through this function is subtracted from the number of

sectors configured by USBD_SMSD_SetNumSectors(). These sectors hold the root directory

entries for the specified LUN. A single sector contains 512 bytes, a short file name entry

(also called 8.3 filenames) needs 32 bytes, therefore a single sector has enough space for

16 root directory entries. Please note that when using LFN (long file names) the number of

entries required for a single file is dynamic (depending on the length of the file name).

Notes

(1) Must only be called from USB_SMSD_X_Config() during initialization phase

203 CHAPTER 7 Target API

7.3.1.6 USBD_SMSD_SetVolumeInfo()

Description

Sets the volume name for a specified LUN.

Prototype

int USBD_SMSD_SetVolumeInfo( unsigned Lun,

const char * sVolumeName,

const USB_MSD_LUN_INFO * pLunInfo);

Parameters

Parameter Description

Lun Specifies the logical unit number.

sVolumeName Pointer to a string containing the name of the LUN.

pLunInfo Pointer to USB_MSD_LUN_INFO structure contain all relevant

MSD strings.

Return value

≥ 0 O.K.

< 0 Error

Notes

(1) Must only be called from USB_SMSD_X_Config() during initialization phase

204 CHAPTER 7 Target API

7.3.1.7 USBD_SMSD_AddConstFiles()

Description

Adds constant files to SmartMSD. Allows to add multiple files which should be shown on a

SmartMSD volume as soon as it is connected. A common example would be a “Readme.txt”

or a link to the company website.

Prototype

int USBD_SMSD_AddConstFiles( unsigned Lun,

const USB_SMSD_CONST_FILE * paConstFile,

unsigned NumFiles);

Parameters

Parameter Description

Lun Specifies the logical unit number.

paConstFile Pointer to an array of USB_SMSD_CONST_FILE structures.

NumFiles The number of items in the paConstFile array.

Return value

≥ 0 O.K.

< 0 Error

Additional information

For additional information please see USB_SMSD_CONST_FILE.

Notes

(1) Must only be called from USB_SMSD_X_Config() during initialization phase

Example

#define COUNTOF(a) (sizeof((a))/sizeof((a)[0]))

static const U8 _abFile_SeggerHTML[] = {0x3C, 0x68, 0x74, 0x6D, 0x6C, 0x3E, 0x3C,

0x68, 0x65, 0x61, 0x64, 0x3E, 0x3C, 0x6D, 0x65, 0x74, 0x61, 0x20, 0x68, 0x74, 0x74,

0x70, 0x2D, 0x65, 0x71, 0x75, 0x69, 0x76, 0x3D, 0x22, 0x72, 0x65, 0x66, 0x72, 0x65,

0x73, 0x68, 0x22, 0x20, 0x63, 0x6F, 0x6E, 0x74, 0x65, 0x6E, 0x74, 0x3D, 0x22, 0x30,

0x3B, 0x20, 0x75, 0x72, 0x6C, 0x3D, 0x68, 0x74, 0x74, 0x70, 0x3A, 0x2F, 0x2F, 0x77,

0x77, 0x77, 0x2E, 0x73, 0x65, 0x67, 0x67, 0x65, 0x72, 0x2E, 0x63, 0x6F, 0x6D, 0x2F,

0x69, 0x6E, 0x64, 0x65, 0x78, 0x2E, 0x68, 0x74, 0x6D, 0x6C, 0x22, 0x2F, 0x3E, 0x3C,

0x74, 0x69, 0x74, 0x6C, 0x65, 0x3E, 0x53, 0x45, 0x47, 0x47, 0x45, 0x52, 0x20, 0x53,

0x68, 0x6F, 0x72, 0x74, 0x63, 0x75, 0x74, 0x3C, 0x2F, 0x74, 0x69, 0x74, 0x6C, 0x65,

0x3E, 0x3C, 0x2F, 0x68, 0x65, 0x61, 0x64, 0x3E, 0x3C, 0x62, 0x6F, 0x64, 0x79, 0x3E,

0x3C, 0x2F, 0x62, 0x6F, 0x64, 0x79, 0x3E, 0x3C, 0x2F, 0x68, 0x74, 0x6D, 0x6C, 0x3E};

static USB_SMSD_CONST_FILE _aConstFiles[] = {

// sName pData FileSize Flags

{ "Segger.html", _abFile_SeggerHTML, sizeof(_abFile_SeggerHTML), 0, }

};

/*********************************************************************

* USB_SMSD_X_Config

* Function description

* This function is called by the USB MSD Module during USB_SMSD_Init() and

initializes the SmartMSD volume.

void USB_SMSD_X_Config(void) {

<...>

USBD_SMSD_AddConstFiles(1, &_aConstFiles[0], COUNTOF(_aConstFiles));

<...>

}

205 CHAPTER 7 Target API

7.3.1.8 USBD_SMSD_SetNumSectors()

Description

Sets the number of sectors available on the volume.

Prototype

void USBD_SMSD_SetNumSectors(unsigned Lun,

unsigned NumSectors);

Parameters

Parameter Description

Lun Specifies the logical unit number.

NumSectors Specifies the number of sectors for a LUN.

Notes

(1) Must only be called from USB_SMSD_X_Config() during initialization phase

206 CHAPTER 7 Target API

7.3.1.9 USBD_SMSD_SetSectorsPerCluster()

Description

Set number of sectors per cluster.

Prototype

void USBD_SMSD_SetSectorsPerCluster(unsigned Lun,

unsigned SectorsPerCluster);

Parameters

Parameter Description

Lun Specifies the logical unit number.

SectorsPerCluster Number of sectors per cluster for the LUN.

Additional information

SectorsPerCluster can be anywhere between 1 and 128, but needs to be a power of 2.

Larger clusters save memory because the management overhead is lower, but the maxi-

mum number of files is limited by the number of available clusters.

Notes

(1) Must only be called from USB_SMSD_X_Config() during initialization phase

207 CHAPTER 7 Target API

7.3.2 Data structures

7.3.2.1 USB_SMSD_CONST_FILE

Description

This structure contains information about a constant file which cannot be changed at run

time and should be shown inside the SmartMSD volume (e.g. Readme.txt). This structure

is a parameter for the USBD_SMSD_AddConstFiles() function.

Type definition

typedef struct {

const char * sName;

const U8 * pData;

unsigned FileSize;

U32 Flags;

} USB_SMSD_CONST_FILE;

Structure members

Member Description

sName Pointer to a zero-terminated string containing the filename.

pData Pointer to the file data. Can be NULL.

FileSize Size of the file. Normally the size of the data pointed to by

pData.

Flags

Can be one of the following items:

•USB_SMSD_FILE_WRITABLE: The file is writable

•USB_SMSD_FILE_AHEAD: File is located at the start of the

volume. Normally constant files are allocated at the end

of the volume.

Additional information

If a file does not occupy complete sectors the remaining bytes of the last sector are auto-

matically filled with 0s on read. If pData is NULL the file is not displayed in the volume.

This is useful when the application has certain files which should only be displayed after

certain events (e.g. the application displays a Fail.txt when the device is reconnected after

an unsuccessful firmware update).

208 CHAPTER 7 Target API

7.3.2.2 USB_SMSD_USER_FUNC_API

Description

This structure contains the function pointers for user provided functions. This structure is

a parameter for the USBD_SMSD_SetUserAPI() function.

Type definition

typedef struct {

USB_SMSD_ON_READ_FUNC * pfOnReadSector;

USB_SMSD_ON_WRITE_FUNC * pfOnWriteSector;

USB_SMSD_MEM_ALLOC * pfMemAlloc;

USB_SMSD_MEM_FREE * pfMemFree;

} USB_SMSD_USER_FUNC_API;

Structure members

Member Description

pfOnReadSector

Pointer to a callback function of type

USB_SMSD_ON_READ_FUNC which is called when a sector is

read from the host. This function is mandatory and can not

be NULL.

pfOnWriteSector

Pointer to a callback function of type

USB_SMSD_ON_WRITE_FUNC which is called when a sector is

written from the host. This function is mandatory and can

not be NULL.

pfMemAlloc

Pointer to a user provided alloc function of type

USB_SMSD_MEM_ALLOC. If this pointer is NULL the internal

alloc function is called. If no memory block is assigned

USB_PANIC is called.

pfMemFree Pointer to a user provided free function of type

USB_SMSD_MEM_FREE. If this pointer is NULL the internal free

function is called.

209 CHAPTER 7 Target API

7.3.2.3 USB_SMSD_FILE_INFO

Description

Structure used in the read and write callbacks.

Type definition

typedef struct {

const USB_SMSD_DIR_ENTRY_SHORT * pDirEntry;

} USB_SMSD_FILE_INFO;

Structure members

Member Description

pDirEntry Pointer to a USB_SMSD_DIR_ENTRY_SHORT structure.

Additional information

Check USB_SMSD_ON_READ_FUNC, USB_SMSD_ON_WRITE_FUNC and USB_SMSD_DIR_EN-

TRY_SHORT for more information.

210 CHAPTER 7 Target API

7.3.2.4 USB_SMSD_DIR_ENTRY_SHORT

Description

Structure used to describe an entry with a short file name. This structure is a member of

USB_SMSD_DIR_ENTRY.

Type definition

typedef struct {

U8 acFilename[];

U8 acExt[];

U8 DirAttr;

U8 NTRes;

U8 CrtTimeTenth;

U16 CrtTime;

U16 CrtDate;

U16 LstAccDate;

U16 FstClusHI;

U16 WrtTime;

U16 WrtDate;

U16 FstClusLO;

U32 FileSize;

} USB_SMSD_DIR_ENTRY_SHORT;

Structure members

Member Description

acFilename File name, limited to 8 characters (short file name), padded

with spaces (0x20).

acExt File extension, limited to 3 characters (short file name),

padded with spaces (0x20).

DirAttr File attributes. Available attributes are listed below.

NTRes Reserved for use by Windows NT.

CrtTimeTenth Millisecond stamp at file creation time. This field actually

contains a count of tenths of a second.

CrtTime Creation time.

CrtDate Date file was created.

LstAccDate Last access date. Note that there is no last access time, only

a date. This is the date of last read or write.

FstClusHI High word of this entry?’s first cluster number.

WrtTime Time of last write.

WrtDate Date of last write.

FstClusLO Low word of this entry’?s first cluster number.

FileSize File size in bytes.

Additional information

The following file attributes are available for short dir entries:

Attribute Explanation

USB_SMSD_ATTR_READ_ONLY The file is read-only.

USB_SMSD_ATTR_HIDDEN The file is hidden.

USB_SMSD_ATTR_SYSTEM The file is designated as a system file.

USB_SMSD_ATTR_VOLUME_ID This entry is the volume ID (volume name).

USB_SMSD_ATTR_DIRECTORY The file is a directory.

211 CHAPTER 7 Target API

Attribute Explanation

USB_SMSD_ATTR_ARCHIVE The file has the archive attribute.

USB_SMSD_ATTR_LONG_NAME The file has a long file name.

212 CHAPTER 7 Target API

7.3.3 Function definitions

7.3.3.1 USB_SMSD_ON_READ_FUNC

Description

Callback function prototype that is used when calling the USBD_SMSD_SetUserAPI() func-

tion.

Type definition

typedef int (USB_SMSD_ON_READ_FUNC)( unsigned Lun,

U8 * pData,

U32 Off,

U32 NumBytes,

const USB_SMSD_FILE_INFO * pFile);

Parameters

Parameter Description

Lun Zero-based index for the unit number. Using only one virtual

volume, this parameter is 0.

pData Pointer to a buffer in which the data is stored.

Off Offset in the file which is read by the host.

NumBytes Amount of bytes requested by the host.

pFile Pointer to a USB_SMSD_FILE_INFO structure describing the

file.

Return value

= 0 Success.

≠ 0 An error occurred.

213 CHAPTER 7 Target API

7.3.3.2 USB_SMSD_ON_WRITE_FUNC

Description

Callback function prototype that is used when calling the USBD_SMSD_SetUserAPI() func-

tion.

Type definition

typedef int (USB_SMSD_ON_WRITE_FUNC)( unsigned Lun,

const U8 * pData,

U32 Off,

U32 NumBytes,

const USB_SMSD_FILE_INFO * pFile);

Parameters

Parameter Description

Lun Zero-based index for the unit number. Using only one virtual

volume, this parameter is 0.

pData Pointer to the data to be written (received from the host).

Off Offset in the file which the host writes.

NumBytes Amount of bytes to write.

pFile Pointer to a USB_SMSD_FILE_INFO structure describing the

file.

Return value

= 0 Success.

≠ 0 An error occurred.

Additional information

Depending on the behavior of the host operating system it is possible that pFile is NULL.

In this case we recommend to perform data analysis to recognize the file.

214 CHAPTER 7 Target API

7.3.3.3 USB_SMSD_MEM_ALLOC

Description

Function prototype that is used when memory is being allocated by the SmartMSD module.

Type definition

typedef void * (USB_SMSD_MEM_ALLOC)(U32 Size);

Parameters

Parameter Description

Size Size of the required memory in bytes.

Return value

Pointer to the allocated memory or NULL.

215 CHAPTER 7 Target API

7.3.3.4 USB_SMSD_MEM_FREE

Description

Function prototype that is used when memory is being freed by the SmartMSD module.

Type definition

typedef void (USB_SMSD_MEM_FREE)(void * p);

Parameters

Parameter Description

pPointer to a memory block which was previously allocated by

USB_SMSD_MEM_ALLOC.

Chapter 8

Media Transfer Protocol Class

(MTP)

This chapter gives a general overview of the MTP class and describes how to get the MTP

component running on the target.

217 CHAPTER 8 Overview

8.1 Overview

The Media Transfer Protocol (MTP) is a USB class protocol which can be used to transfer files

to and from storage devices. MTP is an official extension of the Picture Transfer Protocol

(PTP) designed to allow digital cameras to exchange image files with a computer. MTP

extends this by adding support for audio and video files.

MTP is an alternative to Mass Storage Device (MSD) and it operates at the file level, in

contrast to MSD which reads and writes sector data. This type of operation gives MTP some

advantages over MSD:

• The cable can be safely removed during the data transfer without damaging the file

system.

• The file system does not need to be FAT (can be the SEGGER emFile File System (EFS)

or any other proprietary file system)

• The application has full control over which files are visible to the user. Selected files or

directories can be hidden.

• Virtual files can be presented.

• Host and target can access storage simultaneously without conflicts.

MTP is supported by most operating systems out of the box and the installation of additional

drivers is not required.

emUSB-Device-MTP supports the following capabilities:

• File read

• File write

• Format

• File delete

• Directory create

• Directory delete

emUSB-Device-MTP comes as a complete package and contains the following:

• Generic USB handling

• MTP device class implementation

• Storage driver which uses emFile

• Sample application showing how to work with MTP

218 CHAPTER 8 Overview

8.1.1 Getting access to files

An MTP device will be displayed under the “Portable Devices” section in the “Computer”

window when connected to a PC running the Microsoft Windows 7 operating system:

The file and directories stored on the device are accessed in the usual way using the Win-

dows Explorer:

219 CHAPTER 8 Overview

On the Ubuntu Linux operating system a connected MTP device is shown in the “Computer”

window:

The files and directories present on the MTP device can be easily accessed via GUI:

On other operating systems the data stored on MTP devices can be accessed similarly.

220 CHAPTER 8 Overview

8.1.2 Additional information

For more technical details about MTP and PTP follow these links:

MTP specification

PTP specification

221 CHAPTER 8 Configuration

8.2 Configuration

8.2.1 Initial configuration

To get emUSB-Device-MTP up and running as well as doing an initial test, the configuration

as delivered with the sample application should not be modified.

8.2.2 Final configuration

The configuration must only be modified when emUSB-Device is integrated in your final

product. Refer to section emUSB-Device Configuration on page 41 for detailed information

about the generic information functions which have to be adapted.

8.2.3 Class specific configuration

Beside the generic emUSB-Device configuration functions (emUSB-Device Configuration on

page 41), the following should be adapted before the emUSB-Device MTP component is used

in a final product. Example implementations are supplied in the MSD example application

USB_MTP_Start.c, located in the Application directory of emUSB-Device.

An MTP device is required to present an additional information set to the host. These values

are added during the initial call to USBD_MTP_Add().

Example

static const USB_MTP_INFO _MTPInfo = {

"Vendor", // MTP Manufacturer

"Storage device", // MTP Model

"1.0", // MTP DeviceVersion

"0123456789ABCDEF0123456789ABCDEF" // MTP SerialNumber.

// It must be exactly 32 characters long.

};

...

InitData.pMTPInfo = &_MTPInfo;

...

USB_MTP_Add(&InitData);

8.2.4 Compile time configuration

The following macros can be added to USB_Conf.h file in order to configure the behavior

of the MTP component.

The following types of configuration macros exist:

Binary switches "B"

Switches can have a value of either 0 or 1, for deactivated and activated respectively.

Actually, anything other than 0 works, but 1 makes it easier to read a configuration file.

These switches can enable or disable a certain functionality or behavior. Switches are the

simplest form of configuration macros.

Numerical values "N"

Numerical values are used somewhere in the code in place of a numerical constant.

Type Macro Default Description

NMTP_DEBUG_LEVEL 0

Sets the type of diagnostic messages

output at runtime. It can take one of

these values:

0 - no debug messages

1 - only error messages

222 CHAPTER 8 Configuration

Type Macro Default Description

2 - error and log messages

NMTP_MAX_NUM_STORAGES 4

Maximum number of storage units the

storage layer can handle. 4 addition-

al bytes are allocated for each storage

unit.

BMTP_SAVE_FILE_INFO 0

Specifies if the object properties (file

size, write protection, creation date,

modification date and file id) should

be stored in RAM for quick access to

them. 50 additional bytes of RAM are

required for each object when the

switch is set to 1.

NMTP_MAX_FILE_PATH 256 Maximum number of characters in the

path to a file or directory.

BMTP_SUPPORT_UTF8 1

Names of the files and directories

which are exchanged between the

MTP component and the file system

are encoded in UTF-8 format.

223 CHAPTER 8 Running the sample application

8.3 Running the sample application

The directory Application contains a sample application which can be used with emUSB-

Device and the MTP component. To test the emUSB-Device-MTP component, the application

should be built and then downloaded to target. Remove the USB connection and reconnect

the target to the host. The target will enumerate and will be accessible via a file browser.

8.3.1 USB_MTP_Start.c in detail

The main part of the example application USB_MTP_Start.c is implemented in a single task

called MainTask().

// MainTask() - excerpt from USB_MTP_Start.c

void MainTask(void);

void MainTask(void) {

USBD_Init();

_AddMTP();

USBD_Start();

while (1) {

while ((USBD_GetState() & (USB_STAT_CONFIGURED | USB_STAT_SUSPENDED))

!= USB_STAT_CONFIGURED) {

BSP_ToggleLED(0);

USB_OS_Delay(50);

}

BSP_SetLED(0);

USBD_MTP_Task();

}

The first step is to initialize the USB core stack by calling USBD_Init(). The function _Ad-

dMTP() configures all required endpoints, adds the MTP component to emUSB-Device and

assigns a storage medium to it. More than one storage medium can be added. The access

to storage medium is done using a storage driver. emUSB-Device comes with a storage

driver for the SEGGER emFile file system.

// _AddMTP() - excerpt from USB_MTP_Start.c

static void _AddMTP(void) {

USB_MTP_INIT_DATA InitData;

USB_MTP_INST_DATA InstData;

// Add the MTP component to USB stack.

InitData.EPIn = USBD_AddEP(1, USB_TRANSFER_TYPE_BULK,

USB_HS_BULK_MAX_PACKET_SIZE,

NULL, 0);

InitData.EPOut = USBD_AddEP(0, USB_TRANSFER_TYPE_BULK,

USB_HS_BULK_MAX_PACKET_SIZE,

_acReceiveBuffer,

sizeof(_acReceiveBuffer));

InitData.EPInt = USBD_AddEP(1, USB_TRANSFER_TYPE_INT,

10, NULL, 0);

InitData.pObjectList = _aObjectList;

InitData.NumBytesObjectList = sizeof(_aObjectList);

InitData.pDataBuffer = _aDataBuffer;

InitData.NumBytesDataBuffer = sizeof(_aDataBuffer);

InitData.pMTPInfo = &_MTPInfo;

USBD_MTP_Add(&InitData);

// Add a storage driver to MTP component.

InstData.pAPI = &USB_MTP_StorageFS;

InstData.sDescription = "MTP volume";

InstData.sVolumeId = "0123456789";

InstData.DriverData.pRootDir = "";

USBD_MTP_AddStorage(&InstData);

224 CHAPTER 8 Running the sample application

}

The size of _acReceiveBuffer and _aDataBuffer buffers must be a multiple of USB max-

imum packet size. The size of the buffer allocated for the object list, _aObjectList must

be chosen according to the number of files on the storage medium. emUSB-Device-MTP

assigns an internal object to each file or directory requested by the USB host. The USB host

can request all the files and directories present at once or it can request files and directories

as user browses them. An object requires a minimum of 54 bytes. The actual number of

bytes allocated depends on the length of the full path to file/directory.

225 CHAPTER 8 Target API

8.4 Target API

Function Description

API functions

USBD_MTP_Add() Adds an MTP interface to the USB stack.

USBD_MTP_AddStorage() Adds a storage device to emUSB-De-

vice-MTP.

USBD_MTP_Task() Main task function of MTP component

which processes the commands from host.

USBD_MTP_SendEvent() Sends an event notification to the host.

Data structures

USB_MTP_FILE_INFO Structure which stores information about a

file or directory.

USB_MTP_INIT_DATA Structure which stores the parameters of

the MTP interface.

USB_MTP_INFO Structure that is used when initialising the

MTP module.

USB_MTP_INST_DATA Structure which stores the parameters of

storage driver.

USB_MTP_INST_DATA_DRIVER Structure which stores the parameters

passed to the storage driver.

USB_MTP_STORAGE_API Structure that contains callbacks to the

storage driver.

USB_MTP_STORAGE_INFO Structure which stores information about a

storage.

Enums

USB_MTP_EVENT Enum containing the MTP event codes.

226 CHAPTER 8 Target API

8.4.1 API functions

8.4.1.1 USBD_MTP_Add()

Description

Adds an MTP interface to the USB stack.

Prototype

int USBD_MTP_Add(const USB_MTP_INIT_DATA * pInitData);

Parameters

Parameter Description

pInitData Pointer to a USB_MTP_INIT_DATA structure.

Return value

0 - Successfully added.

Additional information

After the initialization of USB core, this is the first function that needs to be called when an

MTP interface is used with emUSB-Device. The structure USB_MTP_INIT_DATA has to be ini-

tialized before USB_MTP_Add() is called. Refer to USB_MTP_INIT_DATA for more information.

227 CHAPTER 8 Target API

8.4.1.2 USBD_MTP_AddStorage()

Description

Adds a storage device to emUSB-Device-MTP.

Prototype

USB_MTP_STORAGE_HANDLE USBD_MTP_AddStorage(const USB_MTP_INST_DATA * pInstData);

Parameters

Parameter Description

pInstData Pointer to a USB_MTP_INST_DATA structure which contains

the parameters of the added storage.

Return value

= 0 Invalid handle, storage could not be added

≠ 0 A valid storage handle, this handle can be used with the USBD_MTP_SendEvent to

indicate an event to the host.

Additional information

It is necessary to call this function immediately after USBD_MTP_Add(). This function adds

a storage device such as a hard drive, MMC/SD card or NAND flash etc., to emUSB-De-

vice-MTP, which will be used as source/destination of data exchange with the host. The

structure USB_MTP_INST_DATA must be initialized before USB_MTP_AddStorage() is called.

Refer to USB_MTP_INST_DATA for more information.

228 CHAPTER 8 Target API

8.4.1.3 USBD_MTP_Task()

Description

Main task function of MTP component which processes the commands from host.

Prototype

void USBD_MTP_Task(void);

Additional information

The USBD_MTP_Task() should be called after the USB device has been successfully enumer-

ated and configured. The function returns when the USB device is detached or suspended.

229 CHAPTER 8 Target API

8.4.1.4 USBD_MTP_SendEvent()

Description

Sends an event notification to the host.

Prototype

void USBD_MTP_SendEvent(USB_MTP_STORAGE_HANDLE hStorage,

USB_MTP_EVENT Event,

void * pPara);

Parameters

Parameter Description

hStorage Handle to a storage that was returned by USBD_MTP_AddS-

torage().

Event

Event that occurred. The following events are currently sup-

ported:

•USB_MTP_EVENT_OBJECTADDED

•USB_MTP_EVENT_OBJECTREMOVED

•USB_MTP_EVENT_STOREADDED

•USB_MTP_EVENT_STOREREMOVED

•USB_MTP_EVENT_OBJECTINFOCHANGED

•USB_MTP_EVENT_STOREFULL

•USB_MTP_EVENT_STORAGEINFOCHANGED

pPara

Pointer to additional information. This parameter depends on

the event. In case of Event =

•USB_MTP_EVENT_OBJECTADDED

•USB_MTP_EVENT_OBJECTREMOVED

•USB_MTP_EVENT_OBJECTINFOCHANGED

pPara is a pointer to a filled USB_MTP_FILE_INFO structure.

•USB_MTP_EVENT_STOREADDED

•USB_MTP_EVENT_STOREREMOVED

•USB_MTP_EVENT_STORAGEINFOCHANGED

pPara is not used and can be NULL.

Additional information

Sending an event notification to the MTP host makes sure that the MTP host is aware of

changes in the file system of the storage. This function can also be used to notify that a

storage has been added or removed.

Example

static void _GetFileInfo(const char * sPath, USB_MTP_FILE_INFO * pFileInfo) {

const char * s;

U8 AttrFS;

U8 AttrMTP;

memset(pFileInfo, 0, sizeof(USB_MTP_FILE_INFO));

s = strrchr(sPath, '\\');

if (s) {

s++; // Go to the next character after '\'.

} else {

s = sPath;

}

// In case the file path starts with \ skip this.

if (*sPath == '\\') {

sPath++;

230 CHAPTER 8 Target API

}

pFileInfo->pFileName = (char *)s;

pFileInfo->pFilePath = (char *)sPath;

FS_GetFileTimeEx(pFileInfo->pFilePath, &pFileInfo->CreationTime,

FS_FILETIME_CREATE);

FS_GetFileTimeEx(pFileInfo->pFilePath, &pFileInfo->LastWriteTime,

FS_FILETIME_MODIFY);

pFileInfo->IsDirectory = 0;

AttrFS = FS_GetFileAttributes(pFileInfo ? pFilePath);

if (AttrFS & FS_ATTR_DIRECTORY) {

pFileInfo->IsDirectory = 1;

}

AttrMTP = 0;

if (AttrFS & FS_ATTR_READ_ONLY) {

AttrMTP |= MTP_FILE_ATTR_WP;

}

if (AttrFS & FS_ATTR_SYSTEM) {

AttrMTP |= MTP_FILE_ATTR_SYSTEM;

}

if (AttrFS & FS_ATTR_HIDDEN) {

AttrMTP |= MTP_FILE_ATTR_HIDDEN;

}

pFileInfo->Attributes = AttrMTP;

}

static int _WriteLogFile(const char * sLogFilePath) {

char ac[30];

FS_FILE * pFile;

int r = 0;

USB_MTP_FILE_INFO FileInfo = {0};

if (FS_IsVolumeMounted("")) {

// Check whether file already exists

pFile = FS_FOpen(sLogFilePath, "r");

if (pFile) {

r = USB_MTP_EVENT_OBJECTINFOCHANGED;

FS_Fclose(pFile);

} else {

r = USB_MTP_EVENT_OBJECTADDED;

}

pFile = FS_FOpen(sLogFilePath, "a+");

if (pFile) {

sprintf(ac, "OS_Time = %.8d\r\n", (int)OS_GetTime());

FS_Write(pFile, ac, 20);

FS_Fclose(pFile);

} else {

r = 0;

}

_GetFileInfo(sLogFilePath, &FileInfo);

// Send events to the host.

USBD_MTP_SendEvent(_ahStorage[0], (USB_MTP_EVENT)r, &FileInfo);

USBD_MTP_SendEvent(_ahStorage[0], USB_MTP_EVENT_STORAGEINFOCHANGED, NULL);

return r;

}

231 CHAPTER 8 Target API

8.4.2 Data structures

8.4.2.1 USB_MTP_FILE_INFO

Description

Structure which stores information about a file or directory.

Type definition

typedef struct {

char * pFilePath;

char * pFileName;

U32 FileSize;

U32 CreationTime;

U32 LastWriteTime;

U8 IsDirectory;

U8 Attributes;

U8 acId[];

} USB_MTP_FILE_INFO;

Structure members

Member Description

pFilePath Full path to file.

pFileName Pointer to beginning of file/directory name in pFilePath.

FileSize Size of the file in bytes. 0xFFFFFFFF when larger than 4GB.

CreationTime The time and date when the file was created.

LastWriteTime The time and date when the file was last modified.

IsDirectory Set to 1 if the path points to a directory.

Attributes Bitmask of file attributes (MTP_FILE_ATTR_…).

acId Unique identifier which persists between MTP sessions.

Additional information

The date and time is formatted as follows:

Bit

range Value

range Description

0-4 0-29 2-second count

5-10 0-59 Minutes

11-15 0-23 Hours

16-20 1-31 Day of month

21-24 1-12 Month of year

25-31 0-127 Number of years since 1980

The following attributes are supported:

Bitmask Description

MTP_FILE_ATTR_WP File/directory can not be modified.

MTP_FILE_ATTR_SYSTEM File/directory is required for the correct functioning

of the system.

MTP_FILE_ATTR_HIDDEN File/directory should not be shown to the user.

acId should be unique for each file and directory on the file system and it should be per-

sistent between MTP sessions.

232 CHAPTER 8 Target API

8.4.2.2 USB_MTP_INIT_DATA

Description

Structure which stores the parameters of the MTP interface.

Type definition

typedef struct {

U8 EPIn;

U8 EPOut;

U8 EPInt;

void * pObjectList;

U32 NumBytesObjectList;

void * pDataBuffer;

U32 NumBytesDataBuffer;

USB_MTP_INFO * pMTPInfo;

U8 InterfaceNum;

U32 NumBytesAllocated;

U32 NumObjects;

} USB_MTP_INIT_DATA;

Structure members

Member Description

EPIn Endpoint for receiving data from host.

EPOut Endpoint for sending data to host.

EPInt Endpoint for sending events to host.

pObjectList Pointer to a memory region where the list of MTP objects is

stored.

NumBytesObjectList Number of bytes allocated for the object list.

pDataBuffer Pointer to a memory region to be used as communication

buffer.

NumBytesDataBuffer Number of bytes allocated for the data buffer.

pMTPInfo Pointer to a USB_MTP_INFO structure. Filling this structure is

mandatory.

InterfaceNum Internal use.

NumBytesAllocated Internal use.

NumObjects Internal use.

Additional information

This structure holds the endpoints that should be used with the MTP interface. Refer to

USBD_AddEP() for more information about how to add an endpoint.

The number of bytes in the pDataBuffer should be a multiple of USB maximum packet size.

The number of bytes in the object list depends on the number of files/directories on the

storage medium. An object is assigned to each file/directory when the USB host requests

the object information for the first time.

233 CHAPTER 8 Target API

8.4.2.3 USB_MTP_INFO

Description

Structure that is used when initialising the MTP module.

Type definition

typedef struct {

const char * pManufacturer;

const char * pModel;

const char * pDeviceVersion;

const char * pSerialNumber;

} USB_MTP_INFO;

Structure members

Member Description

pManufacturer Name of the device manufacturer.

pModel Model name of the MTP device.

pDeviceVersion Version of the MTP device.

pSerialNumber

Serial number of the MTP device. The serial number should

contain exactly 32 hexadecimal characters. It must be

unique among devices sharing the same model name and

device version strings. The MTP device returns this string in

the Serial Number field of the DeviceInfo dataset. For more

information, refer to MTP specification.

234 CHAPTER 8 Target API

8.4.2.4 USB_MTP_INST_DATA

Description

Structure which stores the parameters of storage driver.

Type definition

typedef struct {

const USB_MTP_STORAGE_API * pAPI;

const char * sDescription;

const char * sVolumeId;

USB_MTP_INST_DATA_DRIVER DriverData;

} USB_MTP_INST_DATA;

Structure members

Member Description

pAPI Pointer to a structure that holds the storage device driver

API.

sDescription Human-readable string which identifies the storage. This

string is displayed in Nautilus/Windows Explorer/etc.

sVolumeId Unique volume identifier

DriverData

Driver data that are passed to the storage driver. Refer to

USB_MTP_INST_DATA_DRIVER for detailed information about

how to initialize this structure. This field must be up to 256

characters long but only the first 128 are significant and

these must be unique for all storages of an MTP device.

Additional information

The MTP device returns the sDescription string in the Storage Description parameter and

the sVolumeId in the Volume Identifier of the StorageInfo dataset. For more information,

refer to MTP specification.

235 CHAPTER 8 Target API

8.4.2.5 USB_MTP_INST_DATA_DRIVER

Description

Structure which stores the parameters passed to the storage driver.

Type definition

typedef struct {

const char * pRootDir;

U8 IsRemovable;

} USB_MTP_INST_DATA_DRIVER;

Structure members

Member Description

pRootDir Path to directory to be used as the root of the storage.

IsRemovable Internal use.

Additional information

pRootDir can specify the root of the file system or any other subdirectory.

236 CHAPTER 8 Target API

8.4.2.6 USB_MTP_STORAGE_API

Description

Structure that contains callbacks to the storage driver.

Type definition

typedef struct {

USB_MTP_STORAGE_INIT * pfInit;

USB_MTP_STORAGE_GET_INFO * pfGetInfo;

USB_MTP_STORAGE_FIND_FIRST_FILE * pfFindFirstFile;

USB_MTP_STORAGE_FIND_NEXT_FILE * pfFindNextFile;

USB_MTP_STORAGE_OPEN_FILE * pfOpenFile;

USB_MTP_STORAGE_CREATE_FILE * pfCreateFile;

USB_MTP_STORAGE_READ_FROM_FILE * pfReadFromFile;

USB_MTP_STORAGE_WRITE_TO_FILE * pfWriteToFile;

USB_MTP_STORAGE_CLOSE_FILE * pfCloseFile;

USB_MTP_STORAGE_REMOVE_FILE * pfRemoveFile;

USB_MTP_STORAGE_CREATE_DIR * pfCreateDir;

USB_MTP_STORAGE_REMOVE_DIR * pfRemoveDir;

USB_MTP_STORAGE_FORMAT * pfFormat;

USB_MTP_STORAGE_RENAME_FILE * pfRenameFile;

USB_MTP_STORAGE_DEINIT * pfDeInit;

USB_MTP_STORAGE_GET_FILE_ATTRIBUTES * pfGetFileAttributes;

USB_MTP_STORAGE_MODIFY_FILE_ATTRIBUTES * pfModifyFileAttributes;

USB_MTP_STORAGE_GET_FILE_CREATION_TIME * pfGetFileCreationTime;

USB_MTP_STORAGE_GET_FILELAST_WRITE_TIME * pfGetFileLastWriteTime;

USB_MTP_STORAGE_GET_FILE_ID * pfGetFileId;

USB_MTP_STORAGE_GET_FILE_SIZE * pfGetFileSize;

} USB_MTP_STORAGE_API;

Structure members

Member Description

pfInit Initializes the storage medium.

pfGetInfo Returns information about the storage medium such as stor-

age capacity and the available free space.

pfFindFirstFile Returns information about the first file in a given directory.

pfFindNextFile Moves to next file and returns information about it.

pfOpenFile Opens an existing file.

pfCreateFile Creates a new file.

pfReadFromFile Reads data from the current file.

pfWriteToFile Writes data to current file.

pfCloseFile Closes the current file.

pfRemoveFile Removes a file from storage medium.

pfCreateDir Creates a new directory.

pfRemoveDir Removes a directory from storage medium.

pfFormat Formats the storage.

pfRenameFile Changes the name of a file or directory.

pfDeInit De-initializes the storage medium.

pfGetFileAttributes Reads the attributes of a file or directory.

pfModifyFileAttribut-

es Changes the attributes of a file or directory.

pfGetFileCreationTime Returns the creation time of a file or directory.

237 CHAPTER 8 Target API

Member Description

pfGetFileLastWrite-

Time Returns the time of the last modification made to a file or di-

rectory.

pfGetFileId Returns the unique ID of a file or directory.

pfGetFileSize Returns the size of a file in bytes.

Additional information

USB_MTP_STORAGE_API is used to retrieve information from the storage device driver or

access data that needs to be read or written. Detailed information can be found in MTP

Storage Driver on page 241.

238 CHAPTER 8 Target API

8.4.2.7 USB_MTP_STORAGE_INFO

Description

Structure which stores information about a storage.

Type definition

typedef struct {

U32 NumKBytesTotal;

U32 NumKBytesFreeSpace;

U16 FSType;

U8 IsWriteProtected;

U8 IsRemovable;

char DirDelimiter;

} USB_MTP_STORAGE_INFO;

Structure members

Member Description

NumKBytesTotal Storage capacity in kBytes

NumKBytesFreeSpace Available free space on storage in kBytes

FSType Type of file system as specified by MTP

IsWriteProtected Set to 1 if the storage medium can not be modified

IsRemovable Set to 1 if the storage medium can be removed from device

DirDelimiter Character which separates the directory/file names in a path

239 CHAPTER 8 Target API

8.4.3 Enums

8.4.3.1 USB_MTP_EVENT

Description

Enum containing the MTP event codes.

Type definition

typedef enum {

USB_MTP_EVENT_UNDEFINED,

USB_MTP_EVENT_CANCELTRANSACTION,

USB_MTP_EVENT_OBJECTADDED,

USB_MTP_EVENT_OBJECTREMOVED,

USB_MTP_EVENT_STOREADDED,

USB_MTP_EVENT_STOREREMOVED,

USB_MTP_EVENT_DEVICEPROPCHANGED,

USB_MTP_EVENT_OBJECTINFOCHANGED,

USB_MTP_EVENT_DEVICEINFOCHANGED,

USB_MTP_EVENT_REQUESTOBJECTTRANSFER,

USB_MTP_EVENT_STOREFULL,

USB_MTP_EVENT_DEVICERESET,

USB_MTP_EVENT_STORAGEINFOCHANGED,

USB_MTP_EVENT_CAPTURECOMPLETE,

USB_MTP_EVENT_UNREPORTEDSTATUS,

USB_MTP_EVENT_OBJECTPROPCHANGED,

USB_MTP_EVENT_OBJECTPROPDESCCHANGED,

USB_MTP_EVENT_OBJECTREFERENCESCHANGED

} USB_MTP_EVENT;

Enumeration constants

Constant Description

USB_MTP_EVENT_UNDEFINED This event code is undefined, and is

not used

USB_MTP_EVENT_CANCELTRANSACTION

This event is used to initiate the can-

cellation of a transaction over trans-

ports which do not have their own

mechanism for cancelling transac-

tions. Currently not used.

USB_MTP_EVENT_OBJECTADDED This event informs the host about a

new object that has been added to the

storage.

USB_MTP_EVENT_OBJECTREMOVED Informs the host that an object has

been removed.

USB_MTP_EVENT_STOREADDED

This event indicates that a storage has

been added to the device. It allows to

dynamically show the available stor-

ages.

USB_MTP_EVENT_STOREREMOVED

This event indicates that a storage has

been removed to the device. It allows

to dynamically hide the available stor-

ages.

USB_MTP_EVENT_DEVICEPROPCHANGED A property changed on the device has

occurred. Currently not used.

USB_MTP_EVENT_OBJECTINFOCHANGED

This event indicates that the infor-

mation for a particular object has

changed and that the host should ac-

quire the information once again.

240 CHAPTER 8 Target API

Constant Description

USB_MTP_EVENT_DEVICEINFOCHANGED

This event indicates that the capabil-

ities of the device have changed and

that the DeviceInfo should be request-

ed again. Currently not used.

USB_MTP_EVENT_REQUESTOBJECTTRANSFER This event can be used by the device

to ask the host to initiate an file object

transfer to him. Currently not used.

USB_MTP_EVENT_STOREFULL This event should be sent when a

storage becomes full.

USB_MTP_EVENT_DEVICERESET Notifies the host about an internal re-

set. Currently not used

USB_MTP_EVENT_STORAGEINFOCHANGED This event is used when information of

a storage changes.

USB_MTP_EVENT_CAPTURECOMPLETE Informs the host that the previously

initiated capture acquire is complete.

Currently not used.

USB_MTP_EVENT_UNREPORTEDSTATUS

This event may be implemented for

certain transports in cases where the

responder unable to report events to

the initiator regarding changes in its

internal status. Currently not used.

USB_MTP_EVENT_OBJECTPROPCHANGED Informs about a change in the object

property of an specific object. Cur-

rently not used.

USB_MTP_EVENT_OBJECTPROPDESCCHANGED

This event informs that the property

description of an object property has

been changed and needs to be re-ac-

quired. Currently not used.

USB_MTP_EVENT_OBJECTREFERENCESCHANGED This event is used to indicate that the

references on an object have been up-

dated. Currently not used.

241 CHAPTER 8 MTP Storage Driver

8.5 MTP Storage Driver

This section describes the emUSB-Device MTP storage interface in detail.

8.5.1 General information

This release comes with USB_MTP_StorageFS driver which uses emFile to access the storage

medium. If you are using emFile this chapter can be ignored. This chapter is for those who

wish to write a file system interface for a third-party file system.

The storage interface is handled through an API-table, which contains all relevant functions

necessary for read/write operations and initialization. Its implementation handles the de-

tails of how data is actually read from or written to memory.

8.5.2 Interface function list

As described above, access to a storage media is realized through an API-function table of

type USB_MTP_STORAGE_API. The structure is declared in USB_MTP.h and it is described in

section Data structures on page 231

242 CHAPTER 8 MTP Storage Driver

8.5.3 USB_MTP_STORAGE_API in detail

8.5.3.1 USB_MTP_STORAGE_INIT

Description

Initializes the storage medium.

Type definition

typedef void (USB_MTP_STORAGE_INIT)( U8 Unit,

const USB_MTP_INST_DATA_DRIVER * pDriverData);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

pFilePath

Pointer to a USB_MTP_INST_DATA_DRIVER structure that con-

tains all information that is necessary for the driver initializa-

tion. For detailed information about the USB_MTP_INST_DA-

TA_DRIVER structure, refer to USB_MTP_INST_DATA_DRIVER.

Additional information

This function is called when the storage driver is added to emUSB-Device-MTP. It is the

first function of the storage driver to be called.

243 CHAPTER 8 MTP Storage Driver

8.5.3.2 USB_MTP_STORAGE_GET_INFO

Description

Returns information about storage medium such as capacity and available free space.

Type definition

typedef void (USB_MTP_STORAGE_GET_INFO)(U8 Unit,

USB_MTP_STORAGE_INFO * pStorageInfo);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

pStorageInfo Pointer to a USB_MTP_STORAGE_INFO structure. For detailed

information about the USB_MTP_STORAGE_INFO structure, re-

fer to USB_MTP_STORAGE_INFO.

Additional information

Typically, this function is called immediately after the device is connected to USB host when

the USB host requests information about the available storage mediums.

244 CHAPTER 8 MTP Storage Driver

8.5.3.3 USB_MTP_STORAGE_FIND_FIRST_FILE

Description

Returns information about the first file in a specified directory.

Type definition

typedef int (USB_MTP_STORAGE_FIND_FIRST_FILE)( U8 Unit,

const char * pDirPath,

USB_MTP_FILE_INFO * pFileInfo);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

pDirPath Full path to the directory to be searched.

pFileInfo out Information about the file/directory found.

Return value

= 0 File/directory found

= 1 No more files/directories found

< 0 An error occurred

Additional information

The “.” and “..” directory entries which are relevant only for the file system should be

skipped.

245 CHAPTER 8 MTP Storage Driver

8.5.3.4 USB_MTP_STORAGE_FIND_NEXT_FILE

Description

Moves to next file and returns information about it.

Type definition

typedef int (USB_MTP_STORAGE_FIND_NEXT_FILE)(U8 Unit,

USB_MTP_FILE_INFO * pFileInfo);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

pFileInfo out Information about the file/directory found.

Return value

= 0 File/directory found

= 1 No more files/directories found

< 0 An error occurred

Additional information

The “.” and “..” directory entries which are relevant only for the file system should be

skipped.

246 CHAPTER 8 MTP Storage Driver

8.5.3.5 USB_MTP_STORAGE_OPEN_FILE

Description

Opens a file for reading.

Type definition

typedef int (USB_MTP_STORAGE_OPEN_FILE)( U8 Unit,

const char * pFilePath);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

pFilePath in Full path to file.

Return value

= 0 File opened

≠ 0 An error occurred

Additional information

This function is called at the beginning of a file read operation. It is followed by one or more

calls to USB_MTP_STORAGE_READ_FROM_FILE. At the end of data transfer the MTP module

closes the file by calling USB_MTP_STORAGE_CLOSE_FILE. If the file does not exists an error

should be returned. The MTP module opens only one file at a time.

247 CHAPTER 8 MTP Storage Driver

8.5.3.6 USB_MTP_STORAGE_CREATE_FILE

Description

Opens a file for writing.

Type definition

typedef int (USB_MTP_STORAGE_CREATE_FILE)( U8 Unit,

const char * pDirPath,

USB_MTP_FILE_INFO * pFileInfo);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

pDirPath in Full path to directory where the file should be created.

pFileInfo

in Information about the file to be created. pFileName

points to the name of the file. out pFilePath points to full

path of created file, pFileName points to the beginning of file

name in pFilePath.

Return value

= 0 File created and opened

≠ 0 An error occurred

Additional information

This function is called at the beginning of a file write operation. The name of the file is

specified in the pFileName filed of pFileInfo. If the file exists it should be truncated to zero

length. When a file is created, the call to USB_MTP_STORAGE_CREATE_FILE is followed by one

or more calls to USB_MTP_STORAGE_WRITE_TO_FILE. If CreationTime and LastWriteTime in

pFileInfo are not zero, these should be used instead of the time stamps generated by

the file system.

248 CHAPTER 8 MTP Storage Driver

8.5.3.7 USB_MTP_STORAGE_READ_FROM_FILE

Description

Reads data from the current file.

Type definition

typedef int (USB_MTP_STORAGE_READ_FROM_FILE)(U8 Unit,

U32 Off,

void * pData,

U32 NumBytes);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

Off Byte offset where to read from.

pData out Data read from file.

NumBytes Number of bytes to read from file.

Return value

= 0 Data read from file

≠ 0 An error occurred

Additional information

The function reads data from the file opened by USB_MTP_STORAGE_OPEN_FILE.

249 CHAPTER 8 MTP Storage Driver

8.5.3.8 USB_MTP_STORAGE_WRITE_TO_FILE

Description

Writes data to current file.

Type definition

typedef int (USB_MTP_STORAGE_WRITE_TO_FILE)( U8 Unit,

U32 Off,

const void * pData,

U32 NumBytes);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

Off Byte offset where to read from.

pData in Data to write to file.

NumBytes Number of bytes to write to file.

Return value

= 0 Data written to file

≠ 0 An error occurred

Additional information

The function writes data to file opened by USB_MTP_STORAGE_CREATE_FILE.

250 CHAPTER 8 MTP Storage Driver

8.5.3.9 USB_MTP_STORAGE_CLOSE_FILE

Description

Closes the current file.

Type definition

typedef int (USB_MTP_STORAGE_CLOSE_FILE)(U8 Unit);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

Return value

= 0 File closed.

≠ 0 An error occurred

Additional information

The function closes the file opened by USB_MTP_STORAGE_CREATE_FILE or USB_MTP_STOR-

AGE_OPEN_FILE.

251 CHAPTER 8 MTP Storage Driver

8.5.3.10 USB_MTP_STORAGE_REMOVE_FILE

Description

Removes a file/directory from the storage medium.

Type definition

typedef int (USB_MTP_STORAGE_REMOVE_FILE)( U8 Unit,

const char * pFilePath);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

pFilePath Full path to file/directory to be removed

Return value

= 0 File removed.

≠ 0 An error occurred

252 CHAPTER 8 MTP Storage Driver

8.5.3.11 USB_MTP_STORAGE_CREATE_DIR

Description

Creates a directory on the storage medium.

Type definition

typedef int (USB_MTP_STORAGE_CREATE_DIR)( U8 Unit,

const char * pDirPath,

USB_MTP_FILE_INFO * pFileInfo);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

pDirPath in Full path to directory where the directory should be cre-

ated.

pFileInfo

in Information about the directory to be created. pFileName

points to the directory name. out pFilePath points to full

path of directory, pFileName points to the beginning of di-

rectory name in pFilePath

Return value

= 0 Directory created.

≠ 0 An error occurred

Additional information

If CreationTime and LastWriteTime in pFileInfo are not available, zero should be used

instead of the time stamps generated by the file system.

253 CHAPTER 8 MTP Storage Driver

8.5.3.12 USB_MTP_STORAGE_REMOVE_DIR

Description

Removes a directory and its contents from the storage medium.

Type definition

typedef int (USB_MTP_STORAGE_REMOVE_DIR)( U8 Unit,

const char * pDirPath);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

pDirPath in Full path to directory to be removed.

Return value

= 0 Directory removed.

≠ 0 An error occurred

Additional information

The function should remove the directory and the entire file tree under it.

254 CHAPTER 8 MTP Storage Driver

8.5.3.13 USB_MTP_STORAGE_FORMAT

Description

Initializes the storage medium.

Type definition

typedef int (USB_MTP_STORAGE_FORMAT)(U8 Unit);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

Return value

= 0 Storage medium initialized.

≠ 0 An error occurred

Additional information

The file system layer has to differentiate between two cases, one where the MTP root di-

rectory is the same as the root directory of the file system and one where it is only a subdi-

rectory of the file system. If pRootDir which was configured in the call to USB_MTP_STOR-

AGE_INIT, points to a subdirectory of the file system, the storage medium should not be

formatted. Instead, all the files and directories underneath pRootDir should be removed.

255 CHAPTER 8 MTP Storage Driver

8.5.3.14 USB_MTP_STORAGE_RENAME_FILE

Description

Changes the name of a file or directory.

Type definition

typedef int (USB_MTP_STORAGE_RENAME_FILE)(U8 Unit,

USB_MTP_FILE_INFO * pFileInfo);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

pFileInfo

Pointer to a USB_MTP_FILE_INFO structure. in Information

about the file/directory to be renamed. pFilePath mem-

ber points to the full path and pFileName points to the new

name. out pFilePath member points to full path of file/di-

rectory with the new name, pFileName points to the begin-

ning of file/directory name in pFilePath. The other structure

fields should also be filled.

Return value

= 0 File/directory renamed.

≠ 0 An error occurred

Additional information

Only the name of the file/directory should be changed. The path to parent directory should

remain the same.

256 CHAPTER 8 MTP Storage Driver

8.5.3.15 USB_MTP_STORAGE_DEINIT

Description

De-initializes the storage medium.

Type definition

typedef void (USB_MTP_STORAGE_DEINIT)(U8 Unit);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

Additional information

Typically called when the application calls USBD_Stop() to de-initialize emUSB-Device.

257 CHAPTER 8 MTP Storage Driver

8.5.3.16 USB_MTP_STORAGE_GET_FILE_ATTRIBUTES

Description

Returns the attributes of a file or directory.

Type definition

typedef int (USB_MTP_STORAGE_GET_FILE_ATTRIBUTES)( U8 Unit,

const char * pFilePath,

U8 * pMask);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

pFilePath Full path to file or directory (0-terminated string).

pMask out The bitmask of the attributes.

Return value

= 0 Information returned.

≠ 0 An error occurred

Additional information

This function is called only when the compile time switch MTP_SAVE_FILE_INFO is set to 0.

For the list of supported attributes refer to USB_MTP_FILE_INFO.

258 CHAPTER 8 MTP Storage Driver

8.5.3.17 USB_MTP_STORAGE_MODIFY_FILE_ATTRIBUTES

Description

Sets and clears file attributes.

Type definition

typedef int (USB_MTP_STORAGE_MODIFY_FILE_ATTRIBUTES)( U8 Unit,

const char * pFilePath,

U8 SetMask,

U8 ClrMask);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

pFilePath Full path to file or directory (0-terminated string).

SetMask The bitmask of the attributes which should be set.

ClrMask The bitmask of the attributes which should be cleared.

Return value

= 0 Attributes modified.

≠ 0 An error occurred

Additional information

This function is called only when the compile time switch MTP_SAVE_FILE_INFO is set to 0.

For the list of supported attributes refer to USB_MTP_FILE_INFO.

259 CHAPTER 8 MTP Storage Driver

8.5.3.18 USB_MTP_STORAGE_GET_FILE_CREATION_TIME

Description

Returns the creation time of file or directory.

Type definition

typedef int (USB_MTP_STORAGE_GET_FILE_CREATION_TIME)( U8 Unit,

const char * pFilePath,

U32 * pTime);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

pFilePath Full path to file or directory (0-terminated string).

pTime out The creation time.

Return value

= 0 Creation time returned.

≠ 0 An error occurred

Additional information

This function is called only when the compile time switch MTP_SAVE_FILE_INFO is set to 0.

For the list of supported attributes refer to USB_MTP_FILE_INFO.

260 CHAPTER 8 MTP Storage Driver

8.5.3.19 USB_MTP_STORAGE_GET_FILELAST_WRITE_TIME

Description

Returns the time when the file or directory was last modified.

Type definition

typedef int (USB_MTP_STORAGE_GET_FILELAST_WRITE_TIME)( U8 Unit,

const char * pFilePath,

U32 * pTime);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

pFilePath Full path to file or directory (0-terminated string).

pTime out The modification time.

Return value

= 0 Modification time returned.

≠ 0 An error occurred

Additional information

This function is called only when the compile time switch MTP_SAVE_FILE_INFO is set to 0.

For the list of supported attributes refer to USB_MTP_FILE_INFO.

261 CHAPTER 8 MTP Storage Driver

8.5.3.20 USB_MTP_STORAGE_GET_FILE_ID

Description

Returns an ID which uniquely identifies the file or directory.

Type definition

typedef int (USB_MTP_STORAGE_GET_FILE_ID)( U8 Unit,

const char * pFilePath,

U8 * pId);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

pFilePath Full path to file or directory (0-terminated string).

pId out The unique ID of file or directory. Should point to a byte

array MTP_NUM_BYTES_FILE_ID large.

Return value

= 0 ID returned.

≠ 0 An error occurred

Additional information

This function is called only when the compile time switch MTP_SAVE_FILE_INFO is set to 0.

262 CHAPTER 8 MTP Storage Driver

8.5.3.21 USB_MTP_STORAGE_GET_FILE_SIZE

Description

Returns the size of a file in bytes.

Type definition

typedef int (USB_MTP_STORAGE_GET_FILE_SIZE)( U8 Unit,

const char * pFilePath,

U32 * pFileSize);

Parameters

Parameter Description

Unit Logical unit number. Specifies for which storage medium the

function is called.

pFilePath Full path to file or directory (0-terminated string).

pFileSize out The size of file in bytes.

Return value

= 0 Size of file returned.

≠ 0 An error occurred

Additional information

This function is called only when the compile time switch MTP_SAVE_FILE_INFO is set to 0.

Chapter 9

Communication Device Class

(CDC)

This chapter describes how to get emUSB-Device up and running as a CDC device.

264 CHAPTER 9 Overview

9.1 Overview

The Communication Device Class (CDC) is an abstract USB class protocol defined by the

USB Implementers Forum. This protocol covers the handling of the following communication

flows:

• VirtualCOM/Serial interface

• Universal modem device

• ISDN communication

• Ethernet communication

This implementation of CDC currently supports the virtual COM/Serial interface, thus the

USB device will behave like a serial interface.

Normally, a custom USB driver is not necessary because a kernel mode driver for USB-

CDC serial communication is delivered by major Microsoft Windows operating systems. For

installing the USB-CDC serial device, an .inf file is needed, which is also delivered. Starting

in Windows 10, such a file is not necessary anymore. A generic inf is provided, handling

devices/interfaces with a Device-/InterfaceClass = 0x02 or Devic-e/InterfaceClass = 0x02

and Device-/InterfaceSubClass = 0x02. Linux handles USB 2 virtual COM ports since Kernel

Ver. 2.4. Further information can be found in the Linux Kernel documentation.

9.1.1 Configuration

The configuration section should later be modified to match the real application. For the

purpose of getting emUSB-Device up and running as well as doing an initial test, the con-

figuration as delivered should not be modified.

265 CHAPTER 9 The example application

9.2 The example application

The start application (in the Application subfolder) is a simple echo server, which can

be used to test emUSB-Device. The application receives data byte by byte and sends it

back to the host.

Source code excerpt from USB_CDC_Start.c:

/*********************************************************************

* MainTask

* USB handling task.

* Modify to implement the desired protocol

void MainTask(void);

void MainTask(void) {

U32 i = 0;

USB_CDC_HANDLE hInst;

USBD_Init();

hInst = _AddCDC();

USBD_Start();

while (1) {

char ac[64];

char acOut[30];

int NumBytesReceived;

int NumBytesToSend;

// Wait for configuration

while ((USBD_GetState() & (USB_STAT_CONFIGURED | USB_STAT_SUSPENDED)) !

= USB_STAT_CONFIGURED) {

BSP_ToggleLED(0);

USB_OS_Delay(50);

}

BSP_SetLED(0);

// Receive at maximum of 64 Bytes

// If less data has been received,

// this should be OK.

NumBytesReceived = USBD_CDC_Receive(hInst, &ac[0], sizeof(ac), 0);

i++;

NumBytesToSend = sprintf(acOut, "%.3lu: Received %d byte(s) -

\"", i, NumBytesReceived);

if (NumBytesReceived > 0) {

USBD_CDC_Write(hInst, &acOut[0], NumBytesToSend, 0);

USBD_CDC_Write(hInst, &ac[0], NumBytesReceived, 0);

USBD_CDC_Write(hInst, "\"\n\r", 3, 0);

}

266 CHAPTER 9 Installing the driver

9.3 Installing the driver

Before connecting the device to the PC, simply start the driver installer (installdriv-

er.exe) which is located in Windows\USB\CDC\ folder. After the executable is executed

Windows may show the UAC message that a specific install program is started. Confirm

with Yes to start installation:

The driver installer will notify that Windows will show up a warning message that the driver

is not signed by Microsoft. The is normal warning for driver that have been signed with a

valid code signing certificate. Confirm read of the message by clicking on the OK button.

The Device Driver Installation Wizard dialog shows up. Click on Next to continue with the

driver installation.

267 CHAPTER 9 Installing the driver

During the driver installation you may be ask whether the device software should be in-

stalled. Since the package is signed with a valid code signing certificate, simply answer

the question with “Install”, optionally you can check the box >>Always trust software from

“SEGGER Microcontroller GmbH & Co. KG”.<<, which would allow to always trust driver

packages coming from SEGGER.

Once the driver is installed the driver wizard will confirm that the driver is successfully

installed.

268 CHAPTER 9 Installing the driver

Now the target device can be connected with the PC. Windows will detect the new hardware.

It will try to find the appropriate driver for the device. After the previous driver installation,

the driver should be found quite fastly and will install it for the device.

To verify that the driver installation was successful, open the device manager by open the

run dialog with [Windows Key]+[r] and Type devmgmt.msc in the Open edit field:

The device manager will open and will show under Ports (COM & LPT) the installed device.

Normally it will be called “USB CDC serial emulation (COMx)” whereas x the assigned COM

port number is.

269 CHAPTER 9 Installing the driver

Double click on the device will show the device properties. Within the Device properties

window the device status will be shown as the “The device is working properly”.

270 CHAPTER 9 Installing the driver

9.3.1 The .inf file

The .inf file is required for installation.

It is defined as:

;

; Device installation file for

; USB 2 COM port emulation

;

; This file supports:

; Windows 2000

; Windows XP

; Windows Server 2003 x86, x64

; Windows Vista x86, x64

; Windows 7 x86,x64

; Windows Server 2008 x86,x64

; Windows 8 x86,x64

; Windows 8.1 x86,x64

;

[Version]

Signature="$Windows NT$"

Class=Ports

ClassGuid={4D36E978-E325-11CE-BFC1-08002BE10318}

Provider=%MFGNAME%

DriverVer=03/12/2015,6.0.2600.5

CatalogFile=usbser.cat

[Manufacturer]

%MFGNAME%=CDCDevice,NT,NTamd64

[DestinationDirs]

DefaultDestDir = 12

[CDCDevice.NT]

%DESCRIPTION%=DriverInstall,USB\VID_8765&PID_0234

[CDCDevice.NTamd64]

%DESCRIPTION%=DriverInstall,USB\VID_8765&PID_0234

[DriverInstall]

Include=mdmcpq.inf

CopyFiles=FakeModemCopyFileSection

AddReg=DriverInstall.AddReg

[DriverInstall.AddReg]

HKR,,DevLoader,,*ntkern

HKR,,NTMPDriver,,usbser.sys

HKR,,EnumPropPages32,,"MsPorts.dll,SerialPortPropPageProvider"

[DriverInstall.Services]

AddService=usbser, 0x00000002, DriverServiceInst

[DriverServiceInst]

DisplayName=%SERVICE%

ServiceType=1

StartType=3

ErrorControl=1

ServiceBinary=%12%\usbser.sys

[SourceDisksNames.amd64]

1=%DiskName%,,

[SourceDisksFiles.amd64]

[SourceDisksNames.x86]

271 CHAPTER 9 Installing the driver

1=%DiskName%,,

[SourceDisksFiles.x86]

[FakeModemCopyFileSection]

[Strings]

MFGNAME = "SEGGER"

DESCRIPTION = "USB CDC serial port emulation"

SERVICE = "USB CDC serial port emulation"

DiskName="SEGGER USB CDC Installation Disk"

red - required modifications

green - possible modifications

You have to personalize the .inf file on the red marked positions. Changes on the green

marked positions are optional and not necessary for the correct function of the device.

Replace the red marked positions with your personal Vendor ID (VID) and Product ID (PID).

These are the value that have been passed by the function USBD_SetDeviceInfo().

9.3.2 Signing the package

Newer Windows versions from Windows Vista on, will only install a driver when the driver

package is signed. This signment must be done with a valid code signing certificate. For

testing purpose the package also be signed in a testing environment, please refer to:

https://msdn.microsoft.com/en-us/windows/hardware/drivers/install/test-

signing-driver-packages

9.3.3 Testing communication to the USB device

The start application is a simple echo server. This means each character that is entered and

sent through the virtual serial port will be sent back by the USB device. A simple Windows

sample application is available to test the start application. The application is located in

Windows\USB\CDC\SampleApplication\Exe.

Alternatively any terminal program, such as PuTTY or TerraTerm or RealTerm, can be used

to check the connectivity.

This section shows how to start and make the first run of the sample application.

• Go to the Windows\USB\CDC\SampleApplication\Exe folder double click on the Echo

application. A console window will be open and will show that one device has been found

with the desired CDC Product and Vendor ID. Enter 0 to connect to that device.

272 CHAPTER 9 Installing the driver

• The application will ask for the amount of bytes the application shall send to and receive

from the target device.

• Now enter the number of repetitions the application shall send and receive to or from

device and confirm with [Enter]..

• The test will run and should look like the following screenshot:

273 CHAPTER 9 Installing the driver

274 CHAPTER 9 Target API

9.4 Target API

This chapter describes the functions and data structures that can be used with the target

application.

9.4.1 Interface function list

Name Description

API functions

USBD_CDC_Add() Adds a CDC ACM class to the stack.

USBD_CDC_CancelRead() Cancel a pending read operation.

USBD_CDC_CancelWrite() Cancel a pending write operation.

USBD_CDC_Read() Reads data from the host.

USBD_CDC_ReadOverlapped() Reads data from the host asynchronously.

USBD_CDC_Receive() Reads data from host.

USBD_CDC_SetOnBreak() Sets a callback in order to inform the ap-

plication about a break condition sent by

the host.

USBD_CDC_SetOnLineCoding() Sets a user callback that shall be called

when a SET_LINE_CODING request is sent

to the device.

USBD_CDC_SetOnControlLineState() Sets a user callback that shall be called

when a SET_LINE_STATE request is sent to

the device.

USBD_CDC_SetOnRXEvent() Sets a callback function for the OUT end-

point that will be called on every RX event

for that endpoint.

USBD_CDC_SetOnTXEvent() Sets a callback function for the IN end-

point that will be called on every TX event

for that endpoint.

USBD_CDC_UpdateSerialState() Sets the new serial state.

USBD_CDC_Write() Writes data to the host.

USBD_CDC_WaitForRX()

This function is to be used in combination

with USBD_CDC_ReadOverlapped() and

waits for the reading data transfer from

the host to complete.

USBD_CDC_WaitForTX() This function is to be used in combina-

tion with a non-blocking call to USBD_CD-

C_Write().

USBD_CDC_WaitForTXReady() Waits (blocking) until the TX queue can ac-

cept another data packet.

USBD_CDC_WriteSerialState() Sends the current control line serial state

to the host.

USBD_CDC_GetNumBytesRemToRead() This function is to be used in combination

with USBD_CDC_ReadOverlapped().

USBD_CDC_GetNumBytesRemToWrite() This function is to be used in combina-

tion with a non-blocking call to USBD_CD-

C_Write().

USBD_CDC_GetNumBytesInBuffer() Returns the number of bytes that are

available in the internal BULK-OUT end-

point buffer.

Data structures

275 CHAPTER 9 Target API

Name Description

USB_CDC_INIT_DATA Initialization structure that is needed when

adding a CDC interface to emUSB-Device.

USB_CDC_LINE_CODING Structure that contains the new line-cod-

ing information sent by the host.

USB_CDC_SERIAL_STATE Structure that contains the serial state

that can be send to the host.

USB_CDC_CONTROL_LINE_STATE Structure that contains the new control

line state sent by the host.

276 CHAPTER 9 Target API

9.4.1.1 USBD_CDC_Add()

Description

Adds a CDC ACM class to the stack.

Prototype

USB_CDC_HANDLE USBD_CDC_Add(const USB_CDC_INIT_DATA * pInitData);

Parameters

Parameter Description

pInitData Pointer to a USB_CDC_INIT_DATA structure.

Return value

Handle to a valid CDC instance. The handle of the first CDC instance is always 0.

Additional information

After the initialization of emUSB-Device, this is the first function that needs to be called

when the USB-CDC interface is used with emUSB-Device. The returned value can be used

with the CDC functions in order to talk to the right CDC instance.

For creating more more than one CDC-Instance please make sure the USB_EnableIAD() is

called before, otherwise none but the first CDC instance will work correctly. The same is

true for composite devices including CDC and another, different USB class.

277 CHAPTER 9 Target API

9.4.1.2 USBD_CDC_CancelRead()

Description

Cancel a pending read operation.

Prototype

void USBD_CDC_CancelRead(USB_CDC_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to a valid CDC instance, returned by USBD_CDC_Ad-

d().

Additional information

This function can be called when a pending asynchronous read operation (triggered by

USBD_CDC_ReadOverlapped()) should be canceled. The function can be called from any

task.

The function can also be used to cancel a call to one of the blocking read functions (when

called from a different task or interrupt function).

278 CHAPTER 9 Target API

9.4.1.3 USBD_CDC_CancelWrite()

Description

Cancel a pending write operation.

Prototype

void USBD_CDC_CancelWrite(USB_CDC_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to a valid CDC instance, returned by USBD_CDC_Ad-

d().

Additional information

This function shall be called when a pending asynchronous write operation (triggered by

non-blocking call to USBD_CDC_Write()) should be canceled. It can be called from any task.

The function can also be used to cancel a call to a blocking write functions (when called

from a different task or interrupt function).

279 CHAPTER 9 Target API

9.4.1.4 USBD_CDC_Read()

Description

Reads data from the host.

Prototype

int USBD_CDC_Read(USB_CDC_HANDLE hInst,

void * pData,

unsigned NumBytes,

unsigned Timeout);

Parameters

Parameter Description

hInst Handle to a valid CDC instance, returned by USBD_CDC_Ad-

d().

pData Pointer to a buffer where the received data will be stored.

NumBytes Number of bytes to read.

Timeout Timeout given in milliseconds. A zero value results in an infi-

nite timeout.

Return value

= NumBytes Requested data was successfully read within the given timeout.

≥ 0 && < NumBytes Timeout has occurred (Number of bytes read before timeout).

< 0 An error occurred.

Additional information

This function blocks the task until all data has been read or a timeout occurs. In case of a

reset or a disconnect USB_STATUS_ERROR is returned.

If the USB stack receives a data packet from the host containing more bytes than requested,

the remaining bytes are stored into the internal buffer of the endpoint, that was provided

via USBD_AddEP(). This data can be retrieved by a later call to USBD_CDC_Receive() /

USBD_CDC_Read(). See also USBD_CDC_GetNumBytesInBuffer().

280 CHAPTER 9 Target API

9.4.1.5 USBD_CDC_ReadOverlapped()

Description

Reads data from the host asynchronously.

Prototype

int USBD_CDC_ReadOverlapped(USB_CDC_HANDLE hInst,

void * pData,

unsigned NumBytes);

Parameters

Parameter Description

hInst Handle to a valid CDC instance, returned by USBD_CDC_Ad-

d().

pData Pointer to a buffer where the received data will be stored.

NumBytes Number of bytes to read.

Return value

≥ 0 Number of bytes that have been read from the internal buffer (success).

= 0 No data was found in the internal buffer (success).

< 0 An error occurred.

Additional information

This function will not block the calling task. The read transfer will be initiated and the

function returns immediately. In order to synchronize, USBD_CDC_WaitForRX() needs to

be called.

Another synchronization method would be to periodically call USBD_CDC_GetNumBytesRem-

ToRead() in order to see how many bytes still need to be received (this method is preferred

when a non-blocking solution is necessary).

The read operation can be canceled using USBD_CDC_CancelRead().

The buffer pointed to by pData must be valid until the read operation is terminated.

Example

See USBD_CDC_GetNumBytesRemToRead on page 295.

281 CHAPTER 9 Target API

9.4.1.6 USBD_CDC_Receive()

Description

Reads data from host. The function blocks until any data have been received. In contrast to

USBD_CDC_Read() this function does not wait for all of NumBytes to be received, but returns

after the first packet has been received or after the timeout occurs.

Prototype

int USBD_CDC_Receive(USB_CDC_HANDLE hInst,

void * pData,

unsigned NumBytes,

int Timeout);

Parameters

Parameter Description

hInst Handle to a valid CDC instance, returned by USBD_CDC_Ad-

d().

pData Pointer to a buffer where the received data will be stored.

NumBytes Number of bytes to read.

Timeout Timeout given in milliseconds. A zero value results in an infi-

nite timeout. If Timeout is -1, the function never blocks.

Return value

> 0 Number of bytes that have been read within the given timeout.

= 0 A timeout occurred (if Timeout > 0), zero packet received (not every controller

supports this!), no data in buffer (if Timeout < 0) or the target was disconnect-

ed during the function call and no data was read so far.

< 0 An error occurred.

Additional information

If no error occurs, this function returns the number of bytes received. Calling USBD_CD-

C_Receive() will return as much data as is currently available up to the size of the buffer

specified within the specified timeout. This function also returns when the target is discon-

nected from the host or when a USB reset occurred during the function call, it will then

return the number of bytes read so far. If the target was disconnected before this function

was called, it returns USB_STATUS_ERROR.

If the USB stack receives a data packet from the host containing more bytes than requested,

the remaining bytes are stored into the internal buffer of the endpoint, that was provided

via USBD_AddEP(). This data can be retrieved by a later call to USBD_CDC_Receive() /

USBD_CDC_Read(). See also USBD_CDC_GetNumBytesInBuffer().

A call of USBD_CDC_Receive(Inst, NULL, 0, -1) can be used to trigger an asynchronous

read that stores the data into the internal buffer.

282 CHAPTER 9 Target API

9.4.1.7 USBD_CDC_SetOnBreak()

Description

Sets a callback in order to inform the application about a break condition sent by the host.

Prototype

void USBD_CDC_SetOnBreak(USB_CDC_HANDLE hInst,

USB_CDC_ON_SET_BREAK * pfOnBreak);

Parameters

Parameter Description

hInst Handle to a valid CDC instance, returned by USBD_CDC_Ad-

d().

pfOnBreak Pointer to the callback function.

Additional information

The callback is called in an ISR context, therefore it should should execute quickly.

The callback function has the following prototype:

typedef void USB_CDC_ON_SET_BREAK(unsigned BreakDuration);

Parameter Description

BreakDuration

Length of the break signal in milliseconds. If Break-

Duration is 0xFFFF, then the host will send a break

until another SendBreak request is received with

BreakDuration of 0x0000.

283 CHAPTER 9 Target API

9.4.1.8 USBD_CDC_SetOnLineCoding()

Description

Sets a user callback that shall be called when a SET_LINE_CODING request is sent to the

device.

Prototype

void USBD_CDC_SetOnLineCoding(USB_CDC_HANDLE hInst,

USB_CDC_ON_SET_LINE_CODING * pf);

Parameters

Parameter Description

hInst Handle to a valid CDC instance, returned by USBD_CDC_Ad-

d().

pf Pointer to the callback function.

Additional information

This function is used to register a user callback which notifies the application that the host

has changed the line coding.

The callback is called in an ISR context, therefore it should should execute quickly.

The callback function has the following prototype:

typedef void USB_CDC_ON_SET_LINE_CODING(USB_CDC_LINE_CODING * pLineCoding);

Parameter Description

pLineCoding Pointer to USB_CDC_LINE_CODING structure contain-

ing the new line coding parameters sent from the

host.

284 CHAPTER 9 Target API

9.4.1.9 USBD_CDC_SetOnControlLineState()

Description

Sets a user callback that shall be called when a SET_LINE_STATE request is sent to the

device.

Prototype

void USBD_CDC_SetOnControlLineState(USB_CDC_HANDLE hInst,

USB_CDC_ON_SET_CONTROL_LINE_STATE * pf);

Parameters

Parameter Description

hInst Handle to a valid CDC instance, returned by USBD_CDC_Ad-

d().

pf Pointer to the callback function.

Additional information

This function is used to register a user callback which notifies the application that the host

has changed the control line state.

The callback is called in an ISR context, therefore it should should execute quickly.

The callback function has the following prototype:

typedef void USB_CDC_ON_SET_CONTROL_LINE_STATE(USB_CDC_CONTROL_LINE_STATE * pLineState);

Parameter Description

pLineState Pointer to USB_CDC_CONTROL_LINE_STATE structure

containing the new line state parameters send from

the host.

285 CHAPTER 9 Target API

9.4.1.10 USBD_CDC_SetOnRXEvent()

Description

Sets a callback function for the OUT endpoint that will be called on every RX event for

that endpoint.

Prototype

void USBD_CDC_SetOnRXEvent(USB_CDC_HANDLE hInst,

USB_EVENT_CALLBACK * pEventCb,

USB_EVENT_CALLBACK_FUNC * pfEventCb,

void * pContext);

Parameters

Parameter Description

hInst Handle to a valid CDC instance, returned by USBD_CDC_Ad-

d().

pEventCb Pointer to a USB_EVENT_CALLBACK structure (will be initial-

ized by this function).

pfEventCb Pointer to the callback routine that will be called on every

event on the USB endpoint.

pContext A pointer which is used as parameter for the callback func-

tion.

Additional information

The USB_EVENT_CALLBACK structure is private to the USB stack. It will be initialized by

USBD_CDC_SetOnRXEvent(). The USB stack keeps track of all event callback functions using

a linked list. The USB_EVENT_CALLBACK structure will be included into this linked list and

must reside in static memory.

The callback function is called only, if a read operation was started using one of the USB-

D_CDC_Read…() functions.

The callback function has the following prototype:

typedef void USB_EVENT_CALLBACK_FUNC(unsigned Events, void *pContext);

Parameter Description

Events A bit mask indicating which events occurred on the

endpoint.

pContext The pointer which was provided to the USBD_SetOn-

Event function.

Note that the callback function will be called within an ISR, therefore it should never block.

The first parameter to the callback function will contain a bit mask for all events that trig-

gered the call:

Event Description

USB_EVENT_DATA_READ Some data was received from the host on the end-

point.

USB_EVENT_READ_COMPLETE The last read operation was completed.

USB_EVENT_READ_ABORT A read transfer was aborted.

286 CHAPTER 9 Target API

Example

// The callback function.

static void _OnEvent(unsigned Events, void *pContext) {

unsigned NumBytes;

if (Events & USB_EVENT_DATA_READ) {

NumBytes = USBD_CDC_GetNumBytesRemToRead(hInst);

if (NumBytes) {

r = USBD_CDC_Receive(hInst, Buff, NumBytes, -1);

if (r > 0) {

<.. process data in Buff..>

}

// Main program.

// Register callback function.

static USB_EVENT_CALLBACK _usb_callback;

USBD_CDC_SetOnRXEvent(hInst, &_usb_callback, _OnEvent, NULL);

// Trigger first read

USBD_CDC_Receive(Inst, NULL, 0, -1);

<.. do anything else here while the data is processed in the callback ..>

287 CHAPTER 9 Target API

9.4.1.11 USBD_CDC_SetOnTXEvent()

Description

Sets a callback function for the IN endpoint that will be called on every TX event for that

endpoint.

Prototype

void USBD_CDC_SetOnTXEvent(USB_CDC_HANDLE hInst,

USB_EVENT_CALLBACK * pEventCb,

USB_EVENT_CALLBACK_FUNC * pfEventCb,

void * pContext);

Parameters

Parameter Description

hInst Handle to a valid CDC instance, returned by USBD_CDC_Ad-

d().

pEventCb Pointer to a USB_EVENT_CALLBACK structure (will be initial-

ized by this function).

pfEventCb Pointer to the callback routine that will be called on every

event on the USB endpoint.

pContext A pointer which is used as parameter for the callback func-

tion.

Additional information

The USB_EVENT_CALLBACK structure is private to the USB stack. It will be initialized by

USBD_CDC_SetOnTXEvent(). The USB stack keeps track of all event callback functions using

a linked list. The USB_EVENT_CALLBACK structure will be included into this linked list and

must reside in static memory.

The callback function is called only, if a write operation was started using one of the USB-

D_CDC_Write…() functions.

The callback function has the following prototype:

typedef void USB_EVENT_CALLBACK_FUNC(unsigned Events, void *pContext);

Parameter Description

Events A bit mask indicating which events occurred on the

endpoint.

pContext The pointer which was provided to the USBD_SetOn-

Event function.

Note that the callback function will be called within an ISR, therefore it should never block.

The first parameter to the callback function will contain a bit mask for all events that trig-

gered the call:

Event Description

USB_EVENT_DATA_SEND Some data was send to the host, so that (part of)

the user write buffer may be reused by the applica-

tion.

USB_EVENT_DATA_ACKED Some data was acknowledged by the host.

USB_EVENT_WRITE_ABORT A write transfer was aborted.

USB_EVENT_WRITE_COMPLETE All write operations were completed.

288 CHAPTER 9 Target API

Example

// The callback function.

static void _OnEvent(unsigned Events, void *pContext) {

if ((Events & USB_EVENT_DATA_SEND) != 0 &&

// Check for last write transfer to be completed.

USBD_CDC_GetNumBytesRemToWrite(_hInst) == 0) {

<.. prepare next data for writing..>

// Send next packet of data.

r = USBD_CDC_Write(_hInst, &ac[0], 200, -1);

if (r < 0) {

<.. error handling..>

}

// Main program.

// Register callback function.

static USB_EVENT_CALLBACK _usb_callback;

USBD_CDC_SetOnTXEvent(hInst, &_usb_callback, _OnEvent, NULL);

// Send the first packet of data using an asynchronous write operation.

r = USBD_CDC_Write(_hInst, &ac[0], 200, -1);

if (r < 0) {

<.. error handling..>

}

<.. do anything else here while the whole data is send..>

289 CHAPTER 9 Target API

9.4.1.12 USBD_CDC_UpdateSerialState()

Description

Sets the new serial state.

Prototype

void USBD_CDC_UpdateSerialState( USB_CDC_HANDLE hInst,

const USB_CDC_SERIAL_STATE * pSerialState);

Parameters

Parameter Description

hInst Handle to a valid CDC instance, returned by USBD_CDC_Ad-

d().

pSerialState Pointer to the USB_CDC_SERIAL_STATE structure.

Additional information

This function updates the control line state internally. In order to inform the host about the

serial state change, refer to the function USBD_CDC_WriteSerialState().

290 CHAPTER 9 Target API

9.4.1.13 USBD_CDC_Write()

Description

Writes data to the host. Depending on the Timeout parameter, the function may block until

NumBytes have been written or a timeout occurs.

Prototype

int USBD_CDC_Write( USB_CDC_HANDLE hInst,

const void * pData,

unsigned NumBytes,

int Timeout);

Parameters

Parameter Description

hInst Handle to a valid CDC instance, returned by USBD_CDC_Ad-

d().

pData Pointer to data that should be sent to the host.

NumBytes Number of bytes to be written.

Timeout Timeout in milliseconds. 0 means infinite. If Timeout is

-1, the function returns immediately and the transfer is

processed asynchronously.

Return value

= 0 Successful started an asynchronous write transfer or a timeout

has occurred and no data was written.

> 0 && < NumBytes Number of bytes that have been written before a timeout oc-

curred.

= NumBytes Write transfer successful completed.

< 0 An error occurred.

Additional information

This function also returns when the target is disconnected from host or when a USB reset

occurred.

The USB stack is able to queue a small number of asynchronous write transfers (Timeout

= -1). If a write transfer is still in progress when this function is called and the USB stack

can not accept another write transfer request, the functions returns USB_STATUS_EP_BUSY.

A synchronous write transfer (Timeout ≥ 0) will always block until the transfer (including

all pending transfers) are finished.

In order to synchronize, USBD_CDC_WaitForTX() needs to be called. Another synchroniza-

tion method would be to periodically call USBD_CDC_GetNumBytesRemToWrite() in order to

see how many bytes still need to be written (this method is preferred when a non-blocking

solution is necessary).

The write operation can be canceled using USBD_CDC_CancelWrite().

If pData = NULL and NumBytes = 0, a zero-length packet is sent to the host.

The content of the buffer pointed to by pData must not be changed until the transfer has

been completed.

291 CHAPTER 9 Target API

9.4.1.14 USBD_CDC_WaitForRX()

Description

This function is to be used in combination with USBD_CDC_ReadOverlapped() and waits for

the reading data transfer from the host to complete.

Prototype

int USBD_CDC_WaitForRX(USB_CDC_HANDLE hInst,

unsigned Timeout);

Parameters

Parameter Description

hInst Handle to a valid CDC instance, returned by USBD_CDC_Ad-

d().

Timeout Timeout in milliseconds. 0 means infinite.

Return value

0 Transfer completed.

1Timeout occurred.

Additional information

This function shall be called in order to synchronize task with the read data transfer previ-

ously initiated. The function blocks until the number of bytes specified by USBD_CDC_Read-

Overlapped() has been read from the host. In case of a timeout, a current transfer is

canceled.

292 CHAPTER 9 Target API

9.4.1.15 USBD_CDC_WaitForTX()

Description

This function is to be used in combination with a non-blocking call to USBD_CDC_Write().

This function waits for the writing data transfer to the host to complete.

Prototype

int USBD_CDC_WaitForTX(USB_CDC_HANDLE hInst,

unsigned Timeout);

Parameters

Parameter Description

hInst Handle to a valid CDC instance, returned by USBD_CDC_Ad-

d().

Timeout Timeout in milliseconds. 0 means infinite.

Return value

0 Transfer completed.

1Timeout occurred.

Additional information

This function shall be called in order to synchronize task with the write data transfer

previously initiated. This function blocks until the number of bytes specified by USBD_CD-

C_Write() has been written to the host. In case of a timeout, a current transfer is canceled.

293 CHAPTER 9 Target API

9.4.1.16 USBD_CDC_WaitForTXReady()

Description

Waits (blocking) until the TX queue can accept another data packet. This function is used in

combination with a non-blocking call to USBD_CDC_Write(), it waits until a new asynchro-

nous write data transfer will be accepted by the USB stack.

Prototype

int USBD_CDC_WaitForTXReady(USB_CDC_HANDLE hInst,

int Timeout);

Parameters

Parameter Description

hInst Handle to a valid CDC instance, returned by USBD_CDC_Ad-

d().

Timeout Timeout in milliseconds. 0 means infinite. If Timeout is neg-

ative, the function will return immediately.

Return value

= 0 A new asynchronous write data transfer will be accepted.

= 1 The write queue is full, a call to USBD_CDC_Write() would return USB_S-

TATUS_EP_BUSY.

< 0 Error occurred.

Additional information

If Timeout is 0, the function never returns 1.

If Timeout is -1, the function will not wait, but immediately return the current state.

Example

// Always keep the write queue full for maximum send speed.

for (;;) {

pData = GetNextData(&NumBytes);

// Wait until stack can accept a new write.

USBD_CDC_WaitForTxReady(hInst, 0);

// Issue write transfer.

if (USBD_CDC_Write(hInst, pData, NumBytes, -1) < 0) {

<.. error handling..>

}

294 CHAPTER 9 Target API

9.4.1.17 USBD_CDC_WriteSerialState()

Description

Sends the current control line serial state to the host.

Prototype

void USBD_CDC_WriteSerialState(USB_CDC_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to a valid CDC instance, returned by USBD_CDC_Ad-

d().

Additional information

This function shall be called in order to inform the host about the control serial state of the

CDC instance. The current control line serial state can be set using USBD_CDC_UpdateSe-

rialState().

295 CHAPTER 9 Target API

9.4.1.18 USBD_CDC_GetNumBytesRemToRead()

Description

This function is to be used in combination with USBD_CDC_ReadOverlapped(). It returns

the number of bytes which still have to be read during the transaction.

Prototype

int USBD_CDC_GetNumBytesRemToRead(USB_CDC_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to a valid CDC instance, returned by USBD_CDC_Ad-

d().

Return value

Number of bytes which still have to be read.

Additional information

Note that this function does not return the number of bytes that have been read, but the

number of bytes which still have to be read. This function does not block.

Example

NumBytesReceived = USBD_CDC_ReadOverlapped(hInst, &ac[0], 50);

if (NumBytesReceived < 0) {

<.. error handling..>

}

if (NumBytesReceived > 0) {

// Already had some data in the internal buffer.

// The first 'NumBytesReceived' bytes may be processed here.

<...>

} else {

// Wait until we get all 50 bytes

while (USBD_CDC_GetNumBytesRemToRead(hInst) > 0) {

USB_OS_Delay(50);

}

296 CHAPTER 9 Target API

9.4.1.19 USBD_CDC_GetNumBytesRemToWrite()

Description

This function is to be used in combination with a non-blocking call to USBD_CDC_Write().

It returns the number of bytes which still have to be written during the transaction.

Prototype

int USBD_CDC_GetNumBytesRemToWrite(USB_CDC_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to a valid CDC instance, returned by USBD_CDC_Ad-

d().

Return value

Number of bytes which still have to be written.

Additional information

Note that this function does not return the number of bytes that have been written, but the

number of bytes which still have to be written. This function does not block.

Example

// NumBytesWritten will contain >

0 values if we had anything in the write buffer.

NumBytesWritten = USBD_CDC_Write(hInst, &ac[0], TRANSFER_SIZE, -1);

if (NumBytesWritten < 0) {

<.. error handling..>

}

// NumBytesToWrite shows how many bytes still have to be written.

while (USBD_CDC_GetNumBytesRemToWrite(hInst) > 0) {

USB_OS_Delay(50);

}

297 CHAPTER 9 Target API

9.4.1.20 USBD_CDC_GetNumBytesInBuffer()

Description

Returns the number of bytes that are available in the internal BULK-OUT endpoint buffer.

Prototype

int USBD_CDC_GetNumBytesInBuffer(USB_CDC_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to a valid CDC instance, returned by USBD_CDC_Ad-

d().

Return value

Number of bytes which have been stored in the internal buffer.

Additional information

The number of bytes returned by this function can be read using USBD_CDC_Read() without

blocking.

298 CHAPTER 9 Target API

9.4.2 Data structures

9.4.2.1 USB_CDC_INIT_DATA

Description

Initialization structure that is needed when adding a CDC interface to emUSB-Device.

Type definition

typedef struct {

U8 EPIn;

U8 EPOut;

U8 EPInt;

} USB_CDC_INIT_DATA;

Structure members

Member Description

EPIn Endpoint for sending data to the host.

EPOut Endpoint for receiving data from the host.

EPInt Endpoint for sending status information.

299 CHAPTER 9 Target API

9.4.2.2 USB_CDC_LINE_CODING

Description

Structure that contains the new line-coding information sent by the host.

Type definition

typedef struct {

U32 DTERate;

U8 CharFormat;

U8 ParityType;

U8 DataBits;

} USB_CDC_LINE_CODING;

Structure members

Member Description

DTERate The data transfer rate for the device in bits per second.

CharFormat

Number of stop bits:

• 0 - 1 Stop bit

• 1 - 1.5 Stop bits

• 2 - 2 Stop bits

ParityType

Specifies the parity type:

• 0 - None

• 1 - Odd

• 2 - Even

• 3 - Mark

• 4 - Space

DataBits Specifies the bits per byte: (5, 6, 7, 8)

300 CHAPTER 9 Target API

9.4.2.3 USB_CDC_SERIAL_STATE

Description

Structure that contains the serial state that can be send to the host.

Type definition

typedef struct {

U8 DCD;

U8 DSR;

U8 Break;

U8 Ring;

U8 FramingError;

U8 ParityError;

U8 OverRunError;

U8 CTS;

} USB_CDC_SERIAL_STATE;

Structure members

Member Description

DCD Data Carrier Detect: Tells that the device is connected to the

telephone line.

DSR Data Set Read: Device is ready to receive data.

Break 1 - Break condition signaled.

Ring Device indicates that it has detected a ring signal on the

telephone line.

FramingError When set to 1, the device indicates a framing error.

ParityError When set to 1, the device indicates a parity error.

OverRunError When set to 1, the device indicates an over-run error.

CTS Deprecated, not specified at USB.org

Additional information

All members of the structure may have value 0 (false) or 1 (true).

301 CHAPTER 9 Target API

9.4.2.4 USB_CDC_CONTROL_LINE_STATE

Description

Structure that contains the new control line state sent by the host.

Type definition

typedef struct {

U8 DTR;

U8 RTS;

} USB_CDC_CONTROL_LINE_STATE;

Structure members

Member Description

DTR Data Terminal Ready.

RTS Request To Send.

Additional information

All members of the structure may have value 0 (false) or 1 (true).

302 CHAPTER 9 Target API

9.4.3 Multithreading

The emUSB CDC target API is not generally thread safe. But it is allowed to handle differ-

ent endpoint in different task in parallel. Examples are:

• A task that performs all reads of data from the host while another task sends data to

the host.

• Operating on different interfaces (e.g. a BULK and a CDC interface) in independent

tasks.

Chapter 10

Human Interface Device Class

(HID)

This chapter gives a general overview of the HID class and describes how to get the HID

component running on the target.

304 CHAPTER 10 Overview

10.1 Overview

The Human Interface Device class (HID) is an abstract USB class protocol defined by the

USB Implementers Forum. This protocol was defined for the handling of devices which are

used by humans to control the operation of computer systems.

An installation of a custom-host USB driver is not necessary, because the USB human

interface device class is standardized and every major OS already provides host drivers

for it.

10.1.1 Further reading

The following documents define the HID class and have been used to implement and verify

the HID component:

• [HID1] Device Class Definition for Human Interface Devices (HID), Firmware

Specification—6/27/01 Version 1.11

• [HID2] HID Usage Tables, 1/21/2005 Version 1.12

10.1.2 Categories

Devices which are in the HID class generally fall into one of two categories:

True HIDs and vendor specific HIDs, explained below. One or more examples for both

categories are provided.

10.1.2.1 True HIDs

True HID devices are devices which communicate directly with the host operating system,

this includes devices which are used by a human to enter data, but do not directly exchange

data with an application program running on the host.

Typical examples

• Keyboard

• Mouse and similar pointing devices

• Joystick

• Gamepad

• Front-panel controls - for example, switches and buttons.

10.1.2.2 Vendor specific HIDs

These are HID devices communicating with an application program. The host OS loads the

same driver it loads for any “true HID” and will automatically enumerate the device, but it

cannot communicate with the device. When analyzing the report descriptor, the host finds

that it cannot exchange information with the device; the device uses a protocol which is

meaningless to the HID driver of the host. The host will therefore not exchange information

with the device. A host recognizes a vendor specific HID by its vendor-defined usage page

in the report descriptor: the numerical value of the usage page lies between 0xFF00 and

0xFFFF.

An application has the chance to communicate with the particular device using API functions

offered by the host. This enables an application program to communicate with the device

without having to load a driver. HID does not take advantage of the full USB bus bandwidth;

bulk communication can be much faster, but requires a driver. Therefore it can be a good

choice to select HID as a device class, especially if ease of use is important and high

communication speed is not required.

Typical examples

• Bar-code reader

• Thermometer

• Voltmeter

• Low-speed JTAG emulator

305 CHAPTER 10 Overview

• UPS (Uninterruptible power supply)

306 CHAPTER 10 Background information

10.2 Background information

10.2.1 HID descriptors

This section presents an overview of the HID class-specific descriptors. The HID descriptors

are defined in the Device Class Definition for Human Interface Devices (HID) of the USB

Implementers Forum. Refer to the USB Implementers Forum website, www.usb.org, for

detailed information about the USB HID standard.

10.2.1.1 HID descriptor

A HID descriptor contains the report descriptor and optionally the physical descriptors.

It specifies the number, type, and size of the report descriptor and the report’s physical

descriptors.

10.2.1.2 Report descriptor

Data between host and device is exchanged in so called “reports”. The report descriptor

defines the format of a report. In general, HIDs require a report descriptor as defined in the

Device Class Definition for Human Interface Devices (HID). The only exception to this are

very basic HIDs such as mice or keyboards. This implementation of HID always requires

a report descriptor.

The USB Implementers Forum provides an application which helps to build and modify HID

report descriptors. The HID Descriptor Tool can be downloaded from:

http://www.usb.org/developers/hidpage/

307 CHAPTER 10 Background information

10.2.1.3 Physical descriptor

Physical descriptor sets are optional descriptors which provide information about the part

or parts of the human body used to activate the controls on a device. Physical descriptors

are currently not supported.

308 CHAPTER 10 Configuration

10.3 Configuration

10.3.1 Initial configuration

To get emUSB-Device up and running as well as doing an initial test, the configuration as it is

delivered should not be modified. The configuration must only be modified if emUSB-Device

should be used in your final product. Refer to the section emUSB-Device Configuration on

page 41 for detailed information about the functions which must be adapted before you

can release a final product version.

10.3.2 Final configuration

Generating a report descriptor

This step is only required if your product is a vendor-specific human interface device. The

report descriptor provided in the example application can typically be used without any

modification. The vendor-defined usage page should be adapted in a final product. Ven-

dor-defined usage pages can be in the range from 0xFF00 to 0xFFFF. The low byte can

be selected by the application programmer. It needs to be identical on both target and

host and should be unique (as unique as an 8-bit value can be). The example(s) use the

value 0x12; this value is defined at the top of the application program with the macro

USB_HID_DEFAULT_VENDOR_PAGE.

309 CHAPTER 10 Example application

10.4 Example application

Example applications are supplied. These can be used for testing the correct installation

and proper function of the device running emUSB-Device.

The following start application files are provided:

File Description

USB_HID_Mouse.c Simple mouse example. (“True HID” example)

USB_HID_Echo1.c Modified echo server. (“vendor specific” example)

10.4.1 USB_HID_Mouse.c

USB_HID_Mouse.c is a typical example for a “true HID” implementation. The host identifies

the device which is programmed with this example as a mouse. After the device is enu-

merated, it moves the mouse cursor in an endless loop to the left and after a short delay

back to the right.

10.4.1.1 Running the example

1. Add USB_HID_Mouse.c to your project and build and download the application into the

target.

2. When you connect your target to the host via USB, Windows will detect the new HID

device.

3. If a connection can be established, it moves the mouse cursor as long as you do not

disconnect your target.

10.4.2 USB_HID_Echo1.c

USB_HID_Echo1.c is a typical example for a “vendor-specific HID” implementation. The HID

start application ( USB_HID_Echo1.c located in the Application subfolder) is a modified

echo server; the application receives data byte by byte, increments every single byte and

sends them back to the host.

310 CHAPTER 10 Example application

To use this application, include the source code file USB_HID_Echo1.c into your project and

compile and download it into your target. Run HIDEcho1.exe after the target is connected

to the host and the enumeration process has been completed. The PC application is supplied

as executable in the Windows\USB\HID\SampleApp\Exe directory. The source code of the

PC example is also supplied. Refer to section Compiling the PC example application for more

information to the PC example project.

10.4.2.1 Running the example

1. Add USB_HID_Echo1.c to your project and build and download the application into the

target.

2. Connect your target to the host via USB while the example application is running,

Windows will detect the new HID device.

3. If a connection can be established, it exchanges data with the target, testing the USB

connection. If the host example application can communicate with the emUSB-Device

device, the example application outputs the product name, Vendor and Product ID and

the report size which will be used to communicate with the target. The target will be

in interactive mode.

Example output of USB_HID_Echo1.exe:

311 CHAPTER 10 Example application

4. Enter the number of reports that should be transmitted when the device is connected.

Every dot in the terminal window indicates a transmission.

10.4.2.2 Compiling the PC example application

Under Window you can build the sample by using the provided VisualStudio 2010 project.

The source code of the example application is located in the subfolder Windows\USB\HID

\SampleApp. Open the file USBHID_Start.sln and compile the source choose Build | Build

SampleApp.exe (Shortcut: F7). To run the executable choose Build | Execute Sam-

pleApp.exe (Shortcut: CTRL-F5).

Note

The Microsoft Windows Driver Development Kit (DDK) is required to compile the HID

host example application. Refer to http://www.microsoft.com/whdc/devtools/ddk/de-

fault.mspx for more information.

Under Linux simply generate the executable by invoking make in the Windows/USB/HID/

SampleApp folder in a shell

cd Windows/USB/HID/SampleApp

make

312 CHAPTER 10 Target API

10.5 Target API

This section describes the functions that can be used on the target system.

General information

To communicate with the host, the example application project includes USB-specific header

and source files. These files contain API functions to communicate with the USB host.

Purpose of the USB Device API functions

To have an easy start up when writing an application on the device side, these API functions

have a simple interface and handle all operations that need to be done to communicate with

the host. Therefore, all operations that need to write to or read from the emUSB-Device

are handled internally by the provided API functions.

313 CHAPTER 10 Target API

10.5.1 Target interface function list

Function Description

API functions

USBD_HID_Add() Adds HID class device to the USB inter-

face.

USBD_HID_GetNumBytesInBuffer() Returns the number of bytes available in

the internal read buffer.

USBD_HID_GetNumBytesRemToRead() Checks how many bytes still have to be

read.

USBD_HID_GetNumBytesRemToWrite() Checks how many bytes still have to be

written.

USBD_HID_Read() Reads data from the host with a given

timeout.

USBD_HID_ReadOverlapped() Reads data from the host asynchronously.

USBD_HID_WaitForRX() This function is to be used in combination

with USBD_HID_ReadOverlapped().

USBD_HID_WaitForTX() This function is to be used in combi-

nation with a non-blocking call to USB-

D_HID_Write().

USBD_HID_Write() Writes data to the host.

USBD_HID_SetOnGetReportRequest() Allows to set a callback for the GET_REPORT

command.

USBD_HID_SetOnSetReportRequest() Allows to set a callback for the SET_REPORT

command.

Data structures

USB_HID_INIT_DATA Initialization structure that is needed when

adding a HID interface to emUSB-Device.

Type definitions

USB_HID_ON_GETREPORT_REQUEST_FUNC Callback function description which is set

via USBD_HID_SetOnGetReportRequest().

USB_HID_ON_SETREPORT_REQUEST_FUNC Callback function description which is set

via USBD_HID_SetOnSetReportRequest().

314 CHAPTER 10 Target API

10.5.2 HID Target API functions

10.5.2.1 USBD_HID_Add()

Description

Adds HID class device to the USB interface.

Prototype

USB_HID_HANDLE USBD_HID_Add(const USB_HID_INIT_DATA * pInitData);

Parameters

Parameter Description

pInitData Pointer to a USB_HID_INIT_DATA structure. For detailed in-

formation refer to USB_HID_INIT_DATA.

Return value

USB_HID_HANDLE: Handle to the HID instance (can be zero).

Additional information

After the initialization of general emUSB-Device, this is the first function that needs to be

called when the USB-HID interface is used with emUSB-Device.

315 CHAPTER 10 Target API

10.5.2.2 USBD_HID_GetNumBytesInBuffer()

Description

Returns the number of bytes available in the internal read buffer.

Prototype

unsigned USBD_HID_GetNumBytesInBuffer(USB_HID_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to an HID handle which is returned by USBD_HID_Ad-

d().

Return value

≥ 0 Number of bytes in the internal read buffer.

316 CHAPTER 10 Target API

10.5.2.3 USBD_HID_GetNumBytesRemToRead()

Description

Checks how many bytes still have to be read.

Prototype

unsigned USBD_HID_GetNumBytesRemToRead(USB_HID_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to an HID instance.

Return value

≥ 0 Number of bytes which have not yet been read.

Additional information

This function is to be used in combination with USBD_HID_ReadOverlapped(). After starting

the read operation this function can be used to periodically check how many bytes still have

to be read. Alternatively the blocking function USBD_HID_WaitForRX() can be used.

317 CHAPTER 10 Target API

10.5.2.4 USBD_HID_GetNumBytesRemToWrite()

Description

Checks how many bytes still have to be written.

Prototype

unsigned USBD_HID_GetNumBytesRemToWrite(USB_HID_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to an HID instance.

Return value

≥ 0 Number of bytes which have not yet been written.

Additional information

This function is to be used in combination with a non-blocking call to USBD_HID_Write().

After starting the write operation this function can be used to periodically check how many

bytes still have to be written. Alternatively the blocking function USBD_HID_WaitForTX()

can be used.

318 CHAPTER 10 Target API

10.5.2.5 USBD_HID_Read()

Description

Reads data from the host with a given timeout.

Prototype

int USBD_HID_Read(USB_HID_HANDLE hInst,

void * pData,

unsigned NumBytes,

unsigned Timeout);

Parameters

Parameter Description

hInst Handle to an HID instance.

pData Pointer to a buffer where the received data will be stored.

NumBytes Number of bytes to read.

Timeout Timeout given in milliseconds. A zero value results in an infi-

nite timeout.

Return value

= NumBytes Requested data was successfully read within the given timeout.

≥ 0, < NumBytes Timeout has occurred. Number of bytes that have been read within

the given timeout.

< 0 Returns a USB_STATUS_ERROR.

Additional information

This function blocks until the timeout has been reached, it has received NumBytes or until

the device is disconnected from the host. This function blocks a task until all data has been

read or a timeout occurs. In case of a reset or a disconnect USB_STATUS_ERROR is returned.

319 CHAPTER 10 Target API

10.5.2.6 USBD_HID_ReadOverlapped()

Description

Reads data from the host asynchronously.

Prototype

int USBD_HID_ReadOverlapped(USB_HID_HANDLE hInst,

void * pData,

unsigned NumBytes);

Parameters

Parameter Description

hInst Handle to a HID instance.

pData Pointer to a buffer where the received data will be stored.

NumBytes Number of bytes to read.

Return value

> 0 Number of bytes that have been read from the internal buffer (success).

= 0 No data was found in the internal buffer (success).

< 0 Error.

Additional information

This function will not block the calling task. The read transfer will be initiated and the

function returns immediately. In order to synchronize, USBD_HID_WaitForRX() needs to be

called. Alternatively the function USBD_HID_GetNumBytesRemToRead() can be called peri-

odically to check whether all bytes have been written or not. The buffer pointed to by pData

must be valid until the read operation is terminated.

320 CHAPTER 10 Target API

10.5.2.7 USBD_HID_WaitForRX()

Description

This function is to be used in combination with USBD_HID_ReadOverlapped(). After the

read function has been called this function can be used to synchronise. It will block until

the transfer is completed.

Prototype

int USBD_HID_WaitForRX(USB_HID_HANDLE hInst,

unsigned Timeout);

Parameters

Parameter Description

hInst Handle to a HID instance.

Timeout Timeout given in milliseconds. A zero value results in an infi-

nite timeout.

Return value

0 Transfer completed.

1Timeout occurred.

Additional information

In case of a timeout, a current transfer is canceled.

321 CHAPTER 10 Target API

10.5.2.8 USBD_HID_WaitForTX()

Description

This function is to be used in combination with a non-blocking call to USBD_HID_Write().

After the write function has been called this function can be used to synchronise. It will

block until the transfer is completed.

Prototype

int USBD_HID_WaitForTX(USB_HID_HANDLE hInst,

unsigned Timeout);

Parameters

Parameter Description

hInst Handle to a HID instance.

Timeout Timeout given in milliseconds. A zero value results in an infi-

nite timeout.

Return value

0 Transfer completed.

1Timeout occurred.

Additional information

In case of a timeout, a current transfer is canceled.

322 CHAPTER 10 Target API

10.5.2.9 USBD_HID_Write()

Description

Writes data to the host. Depending on the Timeout parameter, the function may block until

NumBytes have been written or a timeout occurs.

Prototype

int USBD_HID_Write( USB_HID_HANDLE hInst,

const void * pData,

unsigned NumBytes,

int Timeout);

Parameters

Parameter Description

hInst Handle to an HID instance.

pData Pointer to data that should be sent to the host.

NumBytes Number of bytes to write.

Timeout Timeout in milliseconds. 0 means infinite. If Timeout is

-1, the function returns immediately and the transfer is

processed asynchronously.

Return value

= 0 Successful started an asynchronous write transfer or a timeout

has occurred and no data was written.

> 0 && < NumBytes Number of bytes that have been written before a timeout oc-

curred.

= NumBytes Write transfer successful completed.

< 0 Error occurred.

Additional information

This function also returns when the target is disconnected from host or when a USB reset

occurred.

The USB stack is able to queue a small number of asynchronous write transfers (Timeout

= -1). If a write transfer is still in progress when this function is called and the USB stack

can not accept another write transfer request, the functions returns USB_STATUS_EP_BUSY.

In order to synchronize, USBD_HID_WaitForTX() needs to be called. Another synchroniza-

tion method would be to periodically call USBD_HID_GetNumBytesRemToWrite() in order to

see how many bytes still need to be written (this method is preferred when a non-blocking

solution is necessary).

The content of the buffer pointed to by pData must not be changed until the transfer has

been completed.

323 CHAPTER 10 Target API

10.5.2.10 USBD_HID_SetOnGetReportRequest()

Description

Allows to set a callback for the GET_REPORT command. The GET_REPORT command is sent

from the host to the device.

Prototype

void USBD_HID_SetOnGetReportRequest

(USB_HID_HANDLE hInst,

USB_HID_ON_GETREPORT_REQUEST_FUNC * pfOnGetReportRequest);

Parameters

Parameter Description

hInst Handle to an HID instance.

pfOnGetReportRequest Pointer to a function of type USB_HID_ON_GETREPORT_RE-

QUEST_FUNC.

Additional information

See the description of USB_HID_ON_GETREPORT_REQUEST_FUNC for more details.

324 CHAPTER 10 Target API

10.5.2.11 USBD_HID_SetOnSetReportRequest()

Description

Allows to set a callback for the SET_REPORT command. The SET_REPORT command is sent

from the host to the device.

Prototype

void USBD_HID_SetOnSetReportRequest

(USB_HID_HANDLE hInst,

USB_HID_ON_SETREPORT_REQUEST_FUNC * pfOnSetReportRequest);

Parameters

Parameter Description

hInst Handle to an HID instance.

pfOnSetReportRequest Pointer to a function of type USB_HID_ON_SETREPORT_RE-

QUEST_FUNC .

Additional information

See the description of USB_HID_ON_SETREPORT_REQUEST_FUNC for more details.

325 CHAPTER 10 Target API

10.5.3 Data structures

10.5.3.1 USB_HID_INIT_DATA

Description

Initialization structure that is needed when adding a HID interface to emUSB-Device.

Type definition

typedef struct {

U8 EPIn;

U8 EPOut;

const U8 * pReport;

U16 NumBytesReport;

U16 BuffSize;

U8 * pBuff;

} USB_HID_INIT_DATA;

Structure members

Member Description

EPIn Endpoint for sending data to the host.

EPOut Endpoint for receiving data from the host.

pReport Pointer to a report descriptor.

NumBytesReport Size of the HID report descriptor in bytes.

BuffSize Size of the buffer pointed to by pBuff

pBuff Pointer to a buffer for receiving reports from the host via

endpoint 0 (Set_Report request)

Additional information

To be able to receive data from the host either an endpoint must be allocated (EPOut)

or a buffer must be provided (BufferSize, pBuff). If EPOut = 0 and BufferSize = 0, then

USBD_HID_Read() will not work and all requests from the host will be stalled by the USB

stack. pReport points to a report descriptor. A report descriptor is a structure which is used

to transmit HID control data to and from a human interface device. A report descriptor

defines the format of a report and is composed of report items that define one or more top-

level collections. Each collection defines one or more HID reports. Refer to Universal Serial

Bus Specification, 1.0 Version and the latest version of the HID Usage Tables guide for

detailed information about HID input, output and feature reports. The USB Implementers

Forum provide an application that helps to build and modify HID report descriptors. The

HID Descriptor Tool can be downloaded from: www.usb.org/developers/hidpage/. The re-

port descriptor used in the supplied example application HID_Echo1.c should match to the

requirements of most “vendor specific HID” applications. The report size is defined to 64

bytes. As mentioned before, interrupt endpoints are limited to at most one packet of at

most 64 bytes per frame (on full speed devices).

Example 1 (configure to receive reports via seperate endpoint)

static void _AddHID(void) {

USB_HID_INIT_DATA InitData;

U8 Interval = 10;

static U8 acBuffer[64];

memset(&InitData, 0, sizeof(InitData));

InitData.EPIn = USB_AddEP(USB_DIR_IN, USB_TRANSFER_TYPE_INT, Interval, NULL, 0);

InitData.EPOut = USB_AddEP(USB_DIR_OUT, USB_TRANSFER_TYPE_INT, Interval,

&acBuffer[0], sizeof(acBuffer));

InitData.pReport = _aHIDReport;

InitData.NumBytesReport = sizeof(_aHIDReport);

326 CHAPTER 10 Target API

USBD_HID_Add(&InitData);

}

Example 2 (configure to receive reports via endpoint 0)

static void _AddHID(void) {

USB_HID_INIT_DATA InitData;

U8 Interval = 10;

static U8 acBuffer[64];

memset(&InitData, 0, sizeof(InitData));

InitData.EPIn = USB_AddEP(USB_DIR_IN, USB_TRANSFER_TYPE_INT, Interval, NULL, 0);

InitData.pBuff = &acBuffer[0];

InitData.BufferSize = sizeof(acBuffer);

InitData.pReport = _aHIDReport;

InitData.NumBytesReport = sizeof(_aHIDReport);

USBD_HID_Add(&InitData);

}

327 CHAPTER 10 Target API

10.5.4 Type definitions

10.5.4.1 USB_HID_ON_GETREPORT_REQUEST_FUNC

Description

Callback function description which is set via USBD_HID_SetOnGetReportRequest().

Type definition

typedef int USB_HID_ON_GETREPORT_REQUEST_FUNC( USB_HID_REPORT_TYPE ReportType,

unsigned ReportId,

const U8 * * pData,

U32 * pNumBytes);

Parameters

Parameter Description

ReportType

HID report type, possible values are:

•USB_HID_REPORT_TYPE_INPUT

•USB_HID_REPORT_TYPE_OUTPUT

•USB_HID_REPORT_TYPE_FEATURE

ReportId The ID of the report for which the GET_REPORT request has

been sent.

pData in Pointer to a pointer to the data to send via GET_REPORT

request.

pNumBytes IN: Number of bytes requested. Out: Number of bytes that

shall be sent.

Return value

= 0 No data available. The stack will send a zero length packet as a response.

= 1 Data is available. The stack will send data to the host.

< 0 Data is handled by user application. USB_WriteEP0FromISR needs to be called

from user context.

328 CHAPTER 10 Target API

10.5.4.2 USB_HID_ON_SETREPORT_REQUEST_FUNC

Description

Callback function description which is set via USBD_HID_SetOnSetReportRequest().

Type definition

typedef void USB_HID_ON_SETREPORT_REQUEST_FUNC(USB_HID_REPORT_TYPE ReportType,

unsigned ReportId,

U32 NumBytes);

Parameters

Parameter Description

ReportType

HID report type, possible values are:

•USB_HID_REPORT_TYPE_INPUT

•USB_HID_REPORT_TYPE_OUTPUT

•USB_HID_REPORT_TYPE_FEATURE

ReportId The ID of the report for which the SET_REPORT request has

been sent.

Additional information

In case no EP Out was used with the HID interface, USBD_HID_Read can be used to read

the report that has been sent from the host.

329 CHAPTER 10 Host API

10.6 Host API

This chapter describes the functions that can be used with the Windows host system. This

functions are only required if the emUSB-Device-HID component is used to design a vendor

specific HID.

General information

To communicate with the target USB-HID stack, the example application project includes

a USB-HID specific source and header file (USBHID.c, USBHID.h). These files contain API

functions to communicate with the USB-HID target through the USB-Bulk driver.

Purpose of the USB Host API functions

To have an easy start-up when writing an application on the host side, these API functions

have simple interfaces and handle all operations that need to be done to communicate with

the target USB-HID stack.

330 CHAPTER 10 Host API

10.6.1 Host API function list

Function Description

API functions

USBHID_Close() Close the connection an open device.

USBHID_Open() Opens a handle to a device.

USBHID_Init() Sets the specific vendor page, initializes

the USB HID User API and retrieves the in-

formation of the HID device.

USBHID_Exit() Closes the connection to all open devices

and de-initializes the HID module.

USBHID_GetNumAvailableDevices() Returns the number of available devices.

USBHID_GetProductName() Stores the name of the device into

pBuffer.

USBHID_GetInputReportSize() Returns the input report size of the device.

USBHID_GetOutputReportSize() Returns the output report size of the de-

vice.

USBHID_GetProductId() Returns the product ID of the device.

USBHID_GetVendorId() Returns the vendor ID of the device.

USBHID_RefreshList() Refreshes the connection info list.

USBHID_SetVendorPage() Sets the vendor page so that all HID de-

vice with the specified page will be found.

331 CHAPTER 10 Host API

10.6.2 HID Host API functions

10.6.2.1 USBHID_Close()

Description

Close the connection an open device.

Prototype

void USBHID_Close(unsigned Id);

Parameters

Parameter Description

Id Index of the HID device. This is the bit number of the mask

returned by USBHID_GetNumAvailableDevices().

332 CHAPTER 10 Host API

10.6.2.2 USBHID_Open()

Description

Opens a handle to a device.

Prototype

int USBHID_Open(unsigned Id);

Parameters

Parameter Description

Id Index of the HID device. This is the bit number of the mask

returned by USBHID_GetNumAvailableDevices().

Return value

0 O.K. Opening was successful or already opened.

1 Error. Handle to the device could not opened.

333 CHAPTER 10 Host API

10.6.2.3 USBHID_Init()

Description

Sets the specific vendor page, initializes the USB HID User API and retrieves the information

of the HID device.

Prototype

void USBHID_Init(U8 VendorPage);

Parameters

Parameter Description

VendorPage This parameter specifies the lower 8 bits of the vendor-spe-

cific usage page number. It must be identical on both device

and host.

334 CHAPTER 10 Host API

10.6.2.4 USBHID_Exit()

Description

Closes the connection to all open devices and de-initializes the HID module.

Prototype

void USBHID_Exit(void);

335 CHAPTER 10 Host API

10.6.2.5 USBHID_GetNumAvailableDevices()

Description

Returns the number of available devices.

Prototype

unsigned USBHID_GetNumAvailableDevices(U32 * pMask);

Parameters

Parameter Description

pMask Pointer to unsigned integer value which is used to store the

bit mask of available devices. This parameter may be NULL.

Return value

Number of available devices.

Additional information

pMask will be filled by this routine. It shall be interpreted as a bit mask where a bit set

means this device is available. For example, device 0 and device 2 are available, if pMask

has the value 0x00000005.

336 CHAPTER 10 Host API

10.6.2.6 USBHID_GetProductName()

Description

Stores the name of the device into pBuffer.

Prototype

int USBHID_GetProductName(unsigned Id,

char * pBuffer,

unsigned NumBytes);

Parameters

Parameter Description

Id Index of the HID device. This is the bit number of the mask

returned by USBHID_GetNumAvailableDevices().

pBuffer Pointer to a buffer for the product name.

NumBytes Size of the buffer in bytes.

Return value

0 An error occurred.

1 Success.

337 CHAPTER 10 Host API

10.6.2.7 USBHID_GetInputReportSize()

Description

Returns the input report size of the device.

Prototype

int USBHID_GetInputReportSize(unsigned Id);

Parameters

Parameter Description

Id Index of the HID device. This is the bit number of the mask

returned by USBHID_GetNumAvailableDevices().

Return value

= 0 An error occurred.

≠ 0 Size of the report in bytes.

338 CHAPTER 10 Host API

10.6.2.8 USBHID_GetOutputReportSize()

Description

Returns the output report size of the device.

Prototype

int USBHID_GetOutputReportSize(unsigned Id);

Parameters

Parameter Description

Id Index of the HID device. This is the bit number of the mask

returned by USBHID_GetNumAvailableDevices().

Return value

= 0 An error occurred.

≠ 0 Size of the report in bytes.

339 CHAPTER 10 Host API

10.6.2.9 USBHID_GetProductId()

Description

Returns the product ID of the device.

Prototype

U16 USBHID_GetProductId(unsigned Id);

Parameters

Parameter Description

Id Index of the HID device. This is the bit number of the mask

returned by USBHID_GetNumAvailableDevices().

Return value

= 0 An error occurred.

≠ 0 Product ID.

340 CHAPTER 10 Host API

10.6.2.10 USBHID_GetVendorId()

Description

Returns the vendor ID of the device.

Prototype

U16 USBHID_GetVendorId(unsigned Id);

Parameters

Parameter Description

Id Index of the HID device. This is the bit number of the mask

returned by USBHID_GetNumAvailableDevices().

Return value

= 0 An error occurred.

≠ 0 Vendor ID.

341 CHAPTER 10 Host API

10.6.2.11 USBHID_RefreshList()

Description

Refreshes the connection info list.

Prototype

void USBHID_RefreshList(void);

Additional information

Note that any open handles will be closed while refreshing the connection list.

342 CHAPTER 10 Host API

10.6.2.12 USBHID_SetVendorPage()

Description

Sets the vendor page so that all HID device with the specified page will be found.

Prototype

void USBHID_SetVendorPage(U8 Page);

Parameters

Parameter Description

VendorPage This parameter specifies the lower 8 bits of the vendor-spe-

cific usage page number. It must be identical on both device

and host.

Chapter 11

Printer Class

This chapter describes how to get emUSB-Device up and running as a printer device.

344 CHAPTER 11 Overview

11.1 Overview

The Printer Class is an abstract USB class protocol defined by the USB Implementers Forum.

This protocol delivers the existing printing command-sets to a printer over USB.

11.1.1 Configuration

The configuration section will later on be modified to match the real application. For the

purpose of getting emUSB-Device up and running as well as doing an initial test, the con-

figuration as delivered should not be modified.

345 CHAPTER 11 The example application

11.2 The example application

The start application (in the Application subfolder) is a simple data sink, which can be

used to test emUSB-Device. The application receives data bytes from the host which it

displays in the terminal I/O window of the debugger.

Part of source code of USB_Printer.c:

<...>

/*********************************************************************

* _GetDeviceIdString

static const char * _GetDeviceIdString(void) {

const char * s = "CLASS:PRINTER;MODEL:HP LaserJet 6MP;"

"MANUFACTURER:Hewlett-Packard;"

"DESCRIPTION:Hewlett-Packard LaserJet 6MP Printer;"

"COMMAND SET:PJL,MLC,PCLXL,PCL,POSTSCRIPT;";

return s;

}

/*********************************************************************

* _GetHasNoError

static U8 _GetHasNoError(void) {

return 1;

}

/*********************************************************************

* _GetIsSelected

static U8 _GetIsSelected(void) {

return 1;

}

/*********************************************************************

* _GetIsPaperEmpty

static U8 _GetIsPaperEmpty(void) {

return 0;

}

/*********************************************************************

* _OnDataReceived

static int _OnDataReceived(const U8 * pData, unsigned NumBytes) {

USB_MEMCPY(_acData, pData, NumBytes);

_acData[NumBytes] = 0;

printf(_acData);

return 0;

}

/*********************************************************************

* _OnReset

static void _OnReset(void) {

}

static USB_PRINTER_API _PrinterAPI = {

_GetDeviceIdString,

_OnDataReceived,

_GetHasNoError,

346 CHAPTER 11 The example application

_GetIsSelected,

_GetIsPaperEmpty,

_OnReset

};

/*********************************************************************

* Public code

**********************************************************************

static const USB_DEVICE_INFO _DeviceInfo = {

0x8765, // VendorId

0x2114, // ProductId, should be unique for this sample

"Vendor", // VendorName

"Printer", // ProductName

"12345678901234567890" // SerialNumber

};

/*********************************************************************

* MainTask

* Function description

* USB handling task.

* Modify to implement the desired protocol

void MainTask(void) {

USBD_Init();

USBD_SetDeviceInfo(&_DeviceInfo);

USB_PRINTER_Init(&_PrinterAPI);

USBD_Start();

while (1) {

// Wait for configuration

while ((USBD_GetState() & (USB_STAT_CONFIGURED | USB_STAT_SUSPENDED))

!= USB_STAT_CONFIGURED)

{

BSP_ToggleLED(0);

USB_OS_Delay(50);

}

// Receive and process data.

USB_PRINTER_Task();

}

347 CHAPTER 11 Target API

11.3 Target API

This chapter describes the functions and data structures that can be used with the target

application.

11.3.1 Interface function list

Function Description

API functions

USB_PRINTER_Init() Initializes the printer module.

USB_PRINTER_Task() Processes the requests received from the

USB Host.

USB_PRINTER_TaskEx() Processes the requests received from the

USB Host.

USB_PRINTER_ConfigIRQProcessing() Configure printer class to process received

data in USB interrupt.

Advanced API functions

USB_PRINTER_Read() Reads data from the host.

USB_PRINTER_ReadTimed() Reads data from the host with a given

timeout.

USB_PRINTER_Receive() Reads data from host.

USB_PRINTER_ReceiveTimed() Reads data from host with a given time-

out.

USB_PRINTER_Write() Writes data to the host.

USB_PRINTER_WriteTimed() Writes data to the host within a given

timeout.

Data structures

USB_PRINTER_API Initialization structure that is needed when

adding a printer interface to emUSB-De-

vice.

348 CHAPTER 11 Target API

11.3.2 API functions

11.3.2.1 USB_PRINTER_Init()

Description

Initializes the printer module.

Prototype

void USB_PRINTER_Init(USB_PRINTER_API * pAPI);

Parameters

Parameter Description

pAPI Pointer to an API table that contains all callback functions

that are necessary for handling the functionality of a printer.

Additional information

After the initialization of general emUSB-Device, this is the first function that needs to be

called when the printer class is used with emUSB-Device.

349 CHAPTER 11 Target API

11.3.2.2 USB_PRINTER_Task()

Description

Processes the requests received from the USB Host.

Prototype

void USB_PRINTER_Task(void);

Additional information

This function blocks as long as the USB device is connected to USB host. It handles the

requests by calling the function registered in the call to USB_PRINTER_Init().

350 CHAPTER 11 Target API

11.3.2.3 USB_PRINTER_TaskEx()

Description

Processes the requests received from the USB Host. Uses overlapped read operation for

higher performance.

Prototype

void USB_PRINTER_TaskEx(void);

Additional information

This function blocks as long as the USB device is connected to USB host. It handles the

requests by calling the function registered in the call to USB_PRINTER_Init().

351 CHAPTER 11 Target API

11.3.2.4 USB_PRINTER_ConfigIRQProcessing()

Description

Configure printer class to process received data in USB interrupt. Must be called after

USB_PRINTER_Init() and before USBD_Start(). After calling this function, USB_PRIN-

TER_Task() should never be called.

Prototype

void USB_PRINTER_ConfigIRQProcessing(void);

Additional information

The printer API function pfOnDataReceived is called within the USB interrupt context and

must not block.

352 CHAPTER 11 Target API

11.3.2.5 USB_PRINTER_Read()

Description

Reads data from the host.

Prototype

int USB_PRINTER_Read(void * pData,

unsigned NumBytes);

Parameters

Parameter Description

pData Pointer to a buffer where the received data will be stored.

NumBytes Number of bytes to read.

Return value

= NumBytes Success.

< NumBytes Error occurred.

Additional information

This function blocks a task until all data has been read. In case of a reset or a disconnect

USB_STATUS_ERROR is returned.

353 CHAPTER 11 Target API

11.3.2.6 USB_PRINTER_ReadTimed()

Description

Reads data from the host with a given timeout.

Prototype

int USB_PRINTER_ReadTimed(void * pData,

unsigned NumBytes,

unsigned ms);

Parameters

Parameter Description

pData Pointer to a buffer where the received data will be stored.

NumBytes Number of bytes to read.

ms Timeout in milliseconds. A zero value results in an infinite

timeout.

Return value

= NumBytes Success.

≥ 0, < NumBytes Number of bytes that have been read within the given timeout.

< 0 Error.

Additional information

This function blocks a task until all data has been read or a timeout occurs. In case of a

reset or a disconnect USB_STATUS_ERROR is returned.

354 CHAPTER 11 Target API

11.3.2.7 USB_PRINTER_Receive()

Description

Reads data from host. The function blocks until any data has been received. In contrast

to USB_PRINTER_Read() this function does not wait for all of NumBytes to be received, but

returns after the first packet has been received.

Prototype

int USB_PRINTER_Receive(void * pData,

unsigned NumBytes);

Parameters

Parameter Description

pData Pointer to a buffer where the received data will be stored.

NumBytes Number of bytes to read.

Return value

> 0 Number of bytes that have been read.

= 0 Zero packet received (not every controller supports this!) or the target was dis-

connected during the function call.

< 0 Error.

Additional information

If no error occurs, this function returns the number of bytes received. Calling USB_PRIN-

TER_Receive() will return as much data as is currently available up to the size of the buffer

specified. This function also returns when target is disconnected from host or when a USB

reset occurred, it will then return the number of bytes read.

355 CHAPTER 11 Target API

11.3.2.8 USB_PRINTER_ReceiveTimed()

Description

Reads data from host with a given timeout. The function blocks until any data has been

received. In contrast to USB_PRINTER_ReadTimed() this function does not wait for all of

NumBytes tobe received, but returns after the first packet has been received or after the

timeout has been reached.

Prototype

int USB_PRINTER_ReceiveTimed(void * pData,

unsigned NumBytes,

unsigned ms);

Parameters

Parameter Description

pData Pointer to a buffer where the received data will be stored.

NumBytes Number of bytes to read.

ms Timeout in milliseconds.

Return value

> 0 Number of bytes that have been read within the given timeout.

= 0 Zero packet received (not every controller supports this!) or the target was dis-

connected during the function call.

< 0 Returns a USB_STATUS_ERROR or USB_STATUS_TIMEOUT.

Additional information

If no error occurs, this function returns the number of bytes received. Calling USB_PRIN-

TER_ReceiveTimed() will return as much data as is currently available up to the size of

the buffer specified within the specified timeout. This function also returns when target is

disconnected from host or when a USB reset occurred, it will then return the number of

bytes read.

356 CHAPTER 11 Target API

11.3.2.9 USB_PRINTER_Write()

Description

Writes data to the host.

Prototype

int USB_PRINTER_Write(const void * pData,

unsigned NumBytes);

Parameters

Parameter Description

pData Pointer to a buffer that contains the data to be sent.

NumBytes Number of bytes to write.

Return value

≥ 0 Number of bytes that have been written.

< 0 Error.

Additional information

This function is blocking.

357 CHAPTER 11 Target API

11.3.2.10 USB_PRINTER_WriteTimed()

Description

Writes data to the host within a given timeout.

Prototype

int USB_PRINTER_WriteTimed(const void * pData,

unsigned NumBytes,

int ms);

Parameters

Parameter Description

pData Pointer to a buffer that contains the data to be sent.

NumBytes Number of bytes to write.

ms Timeout in milliseconds. A zero value results in an infinite

timeout. If ms is < 0, the function does not block and may

return USB_STATUS_EP_BUSY.

Return value

> 0 Number of bytes that have been written before timeout.

= 0 Timeout occurred.

< 0 Error.

Additional information

If ms ≥ 0, this function blocks the task until all data has been written or a timeout occurred.

In case of a reset or a disconnect USB_STATUS_ERROR is returned.

358 CHAPTER 11 Target API

11.3.2.11 USB_PRINTER_API

Description

Initialization structure that is needed when adding a printer interface to emUSB-Device. It

holds pointer to callback functions the interface invokes when it processes request from

USB host.

Type definition

typedef struct {

USB_PRINTER_GET_DEVICE_ID_STRING * pfGetDeviceIdString;

USB_PRINTER_ON_DATA_RECEIVED * pfOnDataReceived;

USB_PRINTER_GET_HAS_NO_ERROR * pfGetHasNoError;

USB_PRINTER_GET_IS_SELECTED * pfGetIsSelected;

USB_PRINTER_GET_IS_PAPER_EMPTY * pfGetIsPaperEmpty;

USB_PRINTER_ON_RESET * pfOnReset;

} USB_PRINTER_API;

Structure members

Member Description

pfGetDeviceIdString The library calls this function when the USB host requests

the printer’s identification string.

pfOnDataReceived This function is called when data arrives from USB host.

pfGetHasNoError This function should return a non-zero value if the printer

has no error.

pfGetIsSelected This function should return a non-zero value if the printer is

selected

pfGetIsPaperEmpty This function should return a non-zero value if the printer is

out of paper.

pfOnReset The library calls this function if the USB host sends a soft re-

set command.

Additional information

Detailed information can be found in USB_PRINTER_API in detail on page 360.

359 CHAPTER 11 Printer API

11.4 Printer API

This section describes the emUSB-Device Printer API in detail.

11.4.1 General information

The interface includes multiple callback functions which have to be set by the user appli-

cation. These functions are called by the emUSB-Device stack when the host makes the

corresponding enquiries.

360 CHAPTER 11 Printer API

11.4.2 USB_PRINTER_API in detail

11.4.2.1 USB_PRINTER_GET_DEVICE_ID_STRING

Description

The library calls this function when the USB host requests the printer’s identification string.

This string shall confirm to the IEEE 1284 Device ID Syntax.

Type definition

typedef const char * USB_PRINTER_GET_DEVICE_ID_STRING(void);

Return value

Pointer to the ID string.

Additional information

The return string shall confirm to the IEEE 1284 Device ID.

Example

"CLASS:PRINTER;

MODEL:HP LaserJet 6MP;

MANUFACTURER:Hewlett-Packard;

DESCRIPTION:Hewlett-Packard LaserJet 6MP Printer;

COMMAND SET:PJL,MLC,PCLXL,PCL,POSTSCRIPT;"

361 CHAPTER 11 Printer API

11.4.2.2 USB_PRINTER_ON_DATA_RECEIVED

Description

This function is called when data arrives from USB host.

Type definition

typedef int USB_PRINTER_ON_DATA_RECEIVED(const U8 * pData,

unsigned NumBytes);

Parameters

Parameter Description

pData Pointer to the data.

NumBytes Data length.

Return value

= 0 More data can be accepted

≠ 0 No more data can be accepted, in this case a stall will be sent back to the host.

362 CHAPTER 11 Printer API

11.4.2.3 USB_PRINTER_GET_HAS_NO_ERROR

Description

This function should return a non-zero value if the printer has no error.

Type definition

typedef U8 USB_PRINTER_GET_HAS_NO_ERROR(void);

Return value

= 0 No error.

≠ 0 Error condition present.

363 CHAPTER 11 Printer API

11.4.2.4 USB_PRINTER_GET_IS_SELECTED

Description

This function should return a non-zero value if the printer is selected.

Type definition

typedef U8 USB_PRINTER_GET_IS_SELECTED(void);

Return value

= 0 Not selected.

≠ 0 Selected.

364 CHAPTER 11 Printer API

11.4.2.5 USB_PRINTER_GET_IS_PAPER_EMPTY

Description

This function should return a non-zero value if the printer is out of paper.

Type definition

typedef U8 USB_PRINTER_GET_IS_PAPER_EMPTY(void);

Return value

= 0 Out of paper.

≠ 0 Has paper.

365 CHAPTER 11 Printer API

11.4.2.6 USB_PRINTER_ON_RESET

Description

The library calls this function if the USB host sends a soft reset command.

Type definition

typedef void USB_PRINTER_ON_RESET(void);

Chapter 12

IP-over-USB (IP)

This chapter gives a general overview of the IP component and describes how to get the

IP component running on the target.

367 CHAPTER 12 Overview

12.1 Overview

The IP component is a very convenient package when you need to use IP-based protocols

over USB with different host operating systems. It consist of two different components -

RNDIS and CDC-ECM Combined with the smart capabilities of emUSB-Device-IP to form

a cross-platform USB to Ethernet device that works on every common Host OS that can

handle USB devices.

368 CHAPTER 12 Using only RNDIS or CDC-ECM

12.2 Using only RNDIS or CDC-ECM

Main problem between different Host OSes is that either one IP-over-USB class is supported

which is then not supported on the other Host OS.

Host OS/Protocol RNDIS CDC-ECM

Windows x -

Linux x x

macOS - x

Free/Net/OpenBSD x x

Linux and all BSD distribution work with any IP-over-USB interface and therefore can be

used with either RNDIS or CDC-ECM. macOS does not support RNDIS, third party tools may

work but are not fully compatible and using a new version of macOS the driver or package

may no longer work properly. Windows cannot handle CDC-ECM out-of-the-box. There

are third-party drivers which can handle this but the driver package has to be licensed.

Furthermore a new inf-file needs to be written for your device and as a consequence of

that the driver package itself needs to be certified which involves further costs. Adding new

CDC-ECM devices to the inf-file forces to resign that package once again.

SEGGER’s IP-over-USB solution eliminates these limitations.

12.2.1 Working with emUSB-Device-IP

A IP-over-USB device connected to a PC running the Windows operating system is listed

as a separate network interface in the “Network Connections” window as shown in this

screenshot:

The ping command line utility can be used to test the connection to target as shown below.

If the connection is correctly established the number of the lost packets should be 0.

369 CHAPTER 12 Using only RNDIS or CDC-ECM

On macOS IP-over-USB is similarly available:

And on Ubuntu:

370 CHAPTER 12 Configuration

12.3 Configuration

12.3.1 Initial Configuration

To get emUSB-Device-IP up and running as well as doing an initial test, the configuration

as delivered should not be modified.

12.3.2 Final configuration

The configuration must only be modified when emUSB-Device-IP is used in your final prod-

uct. Refer to section emUSB-Device Configuration on page 41 to get detailed information

about the general emUSB-Device configuration functions which have to be adapted.

12.3.3 Class specific configuration

emUSB-Device-IP specific device information must be provided by the application via the

function USBD_IP_Add(). A sample how to use this function can be found in the IP_Con-

fig_IP_over_USB.c. The file is located in the Sample\IP directory of the emUSB-Device

shipment. The IP_Config_IP_over_USB.c provides a ready to use layer and configuration

file to be used with embOS and embOS/IP.

371 CHAPTER 12 Running the sample application

12.4 Running the sample application

The sample application can be found in the Sample\IP\IP_Config_IP_over_USB.c file of

the emUSB-Device shipment. In order to use the sample application the SEGGER embOS/IP

middleware component is required. To test the emUSB-Device-IP component any of the

embOS/IP sample applications can be used in combination with IP_Config_IP_over_USB.c .

After the sample application is started the USB cable should be connected to the PC and

the chosen embOS/IP sample can be tested by using the URL “usb.local”.

12.4.1 IP_Config_IP_over_USB.c in detail

The main part of the sample application is implemented in the function MainTask() which

runs as an independent task.

// IP_X_Config() - excerpt from IP_Config_IP_over_USB.c

void IP_X_Config(void) {

<...>

IP_SetIFaceConnectHook(IFaceId, _Connect);

IP_AddStateChangeHook(&_Hook, _OnHWChange)

<...>

}

// _Connect() - excerpt from IP_Config_IP_over_USB.c

static int _Connect(unsigned IFaceId) {

// Initialize the DHCP Server for this interface.

IP_DHCPS_Init(IFaceId);

// Initialize the USB stack

// and prepare to use the IP-over-USB connection

USBD_Init();

USBD_SetDeviceInfo(&USB_DeviceInfo);

// Enable IAD makes sure that the device is properly enumerated on Windows

7 on USB 3 Controller

USBD_EnableIAD();

_AddIP();

USBD_Start();

return 0; // Successfully connected.

}

// _AddIP() - excerpt from IP_Config_IP_over_USB.c

static void _AddIP(void) {

USB_IP_INIT_DATA InitData;

InitData.EPOut = USBD_AddEP(USB_DIR_OUT, USB_TRANSFER_TYPE_BULK, 0,

_abReceiveBuffer, sizeof(_abReceiveBuffer));

InitData.EPIn = USBD_AddEP(USB_DIR_IN,

USB_TRANSFER_TYPE_BULK, 0, NULL, 0);

InitData.EPInt = USBD_AddEP(USB_DIR_IN, USB_TRANSFER_TYPE_INT,

5, NULL, 0);

InitData.pDriverAPI = &USB_Driver_IP_NI;

InitData.DriverData.pDriverData = (void *)_IFaceId;

InitData.pRndisDevInfo = &_DeviceInfo;

USBD_IP_Add(&InitData);

}

// _OnHWChange() - excerpt from IP_Config_IP_over_USB.c

static void _OnHWChange(unsigned IFaceId, U8 AdminState, U8 HWState) {

unsigned IsReady;

IP_USE_PARA(AdminState);

IsReady = HWState ? 1 : 0;

372 CHAPTER 12 Running the sample application

_UpdateIPServiceOperation(IFaceId, IsReady);

}

// _UpdateIPServiceOperation() - excerpt from IP_Config_IP_over_USB.c

static void _UpdateIPServiceOperation(unsigned IFaceId, unsigned LinkStatus) {

U32 ServerIpAddr;

U32 SubnetMask;

U32 DNSServer;

U8 USBAddr;

if (IFaceId == _IFaceId) {

if (LinkStatus) {

// As soon as we are enumerated, we know that the USB host has

// assigned a USB address to us.

// We will use this USB address in order to assign

// the embOS/IP interface a IP address.

// The IP address is selected from a so-called

// IP pool for CGN (carrier grade NAT) - RFC6598

// The IP pool for this is 100.64.0.0/10.

// We will use 100.127.<USBAddr>.0/29 -> gives us

// 8 IP addresses, whereas 6 are assignable.

// This is enough for a client/host configuration.

// Therefore we will have the following scenario

// embOS/IP interface: IP: 100.127.<USBAddr>.1

// Host interface: 100.127.<USBAddr>.2 - assigned

// by our DHCP server. SubnetMask = 255.255.255.248

USBAddr = USBD_GetUSBAddr();

ServerIpAddr = IP_BYTES2ADDR(100, 127, USBAddr, 1);

SubnetMask = IP_BYTES2ADDR(0xff,0xff,0xff,0xf8);

// Configure the delayed exec parameters

// IP_SetAddrMaskEx parameters

_SetAddrMaskExPara.Para0 = SEGGER_PTR2ADDR(IFaceId);

_SetAddrMaskExPara.Para1 = SEGGER_PTR2ADDR(ServerIpAddr);

_SetAddrMaskExPara.Para2 = SEGGER_PTR2ADDR(SubnetMask);

// IP_DHCPS_ConfigPool parameters

_DNSServer = ServerIpAddr;

_DHCPS_ConfigPoolPara.Para0 = SEGGER_PTR2ADDR(IFaceId);

_DHCPS_ConfigPoolPara.Para1 = SEGGER_PTR2ADDR(ServerIpAddr + 1);

_DHCPS_ConfigPoolPara.Para2 = SEGGER_PTR2ADDR(SubnetMask);

_DHCPS_ConfigPoolPara.Para3 = SEGGER_PTR2ADDR(4);

// IP_DHCPS_ConfigDNS parameters

_DHCPS_ConfigDNSAddPara.Para0 = SEGGER_PTR2ADDR(IFaceId);

_DHCPS_ConfigDNSAddPara.Para1 = SEGGER_PTR2ADDR(&_DNSServer);

_DHCPS_ConfigDNSAddPara.Para2 = SEGGER_PTR2ADDR(1);

// IP_DHCPS_Start(m)DNS parameters

IP_MEMSET(&_DNSConfig, 0, sizeof(_DNSConfig));

_DNSConfig.sHostname = SERVER_NAME;

_DNSConfig.TTL = 60;

_DNSConfig.apSDConfig = _aSDConfig;

_DNSConfig.NumConfig = SEGGER_COUNTOF(_aSDConfig);

// Queue now the the delayed exec commands

// Assign a local address 100.127.<USBAddr>.1/8

IP_ExecDelayed(&_aIPExecDelayed[IP_SET_ADDRESS_MASK_OPERATION],

IP_SetAddrMaskEx_Delayed,

373 CHAPTER 12 Running the sample application

&_SetAddrMaskExPara,

"SetAddrMaskEx",

_OnDone);

IP_ExecDelayed(&_aIPExecDelayed[IP_DHCPS_CONFIGPOOL_OPERATION],

IP_DHCPS_ConfigPool_Delayed,

&_DHCPS_ConfigPoolPara,

"IP_DHCPS_ConfigPool",

_OnDone);

IP_ExecDelayed(&_aIPExecDelayed[IP_DHCPS_CONFIGDNSADDR_OPERATION],

IP_DHCPS_ConfigDNSAddr_Delayed,

&_DHCPS_ConfigDNSAddPara,

"IP_DHCPS_ConfigDNSAddr",

_OnDone);

IP_ExecDelayed(&_aIPExecDelayed[IP_DHCPS_START_OPERATION],

IP_DHCPS_Start_Delayed,

SEGGER_PTR2ADDR(_IFaceId),

"IP_DHCPS_Start",

_OnDone);

IP_ExecDelayed(&_aIPExecDelayed[IP_MDNS_SERVER_START_OPERATION],

IP_MDNS_SERVER_Start_Delayed,

&_DNSConfig,

"IP_MDNS_SERVER_Start",

_OnDone);

IP_ExecDelayed(&_aIPExecDelayed[IP_DNS_SERVER_START_OPERATION],

IP_DNS_SERVER_Start_Delayed,

&_DNSConfig,

"IP_DNS_SERVER_Start",

_OnDone);

}

if (LinkStatus == 0) {

IP_ExecDelayed(&_aIPExecDelayed[IP_DHCPS_HALT_OPERATION],

IP_DHCPS_Halt_Delayed,

SEGGER_PTR2ADDR(_IFaceId),

"IP_DHCPS_Halt",

_OnDone);

IP_ExecDelayed(&_aIPExecDelayed[IP_MDNS_SERVER_STOP_OPERATION],

IP_MDNS_SERVER_Stop_Delayed,

NULL,

"IP_MDNS_SERVER_Stop",

_OnDone);

IP_ExecDelayed(&_aIPExecDelayed[IP_DNS_SERVER_STOP_OPERATION],

IP_DNS_SERVER_Stop_Delayed,

NULL,

"IP_DNS_SERVER_Stop",

_OnDone);

}

The first step is to initialize the DHCP server component which assigns the IP address for the

PC side. The target is configured with the IP address 100.127.<USBAddr>.1. The USB ad-

dress is assigned by the host PC and is unique in the host system. This makes sure that when

multiple devices using emUSB-Device-IP are connected they receive a different subnet The

DHCP server is configured to distribute IP addresses starting from 100.127.<USBAddr>.2,

therefore the PC will receive the IP address 100.127.<USBAddr>.2. DNS and mDNS is en-

abled to allow name resolution.

374 CHAPTER 12 emUSB-Device-IP + embOS/IP as a "USB

Webserver"

12.5 emUSB-Device-IP + embOS/IP as a "USB

Webserver"

This method of using emUSB-Device-IP provides a unique customer experience where a

USB device can provide a custom web page or any other service through which a customer

can interact with the device.

Initially the PC recognizes an RNDIS device. In case of Windows XP and Vista a driver will be

necessary (the corresponding inf-file can be found in the Windows\USB\RNDIS\WinXP_Vista

folder), Windows 7 and above as well as Linux recognize RNDIS automatically. RNDIS from

the viewpoint of the PC is a normal Network Interface Controller (NIC) and the PC handles it

as such. The default behaviour is to request an IP address from a DHCP server. The PC re-

trieves an IP address from the DHCP-Server in the device. In our standard sample code the

device has the local IP 100.127.<USBAddr>.1 and the PC will get 100.127.<USBAddr>.2

from the DHCP server. With this the configuration is complete and the user can access the

web-interface located on the USB device via the DNS entry - “usb.local”.

375 CHAPTER 12 Target API

12.6 Target API

Function Description

API functions

USBD_IP_Add() Adds support for the IP component to USB

stack.

USBD_IP_Task() Obsolete.

Data structures

USB_IP_INIT_DATA Structure which stores the parameters of

the IP component.

376 CHAPTER 12 Target API

12.6.1 API functions

12.6.1.1 USBD_IP_Add()

Description

Adds support for the IP component to USB stack. Internally CDC-ECM and RNDIS is initial-

ized. The IP component switches automatically between the two.

Prototype

void USBD_IP_Add(const USB_IP_INIT_DATA * pInitData);

Parameters

Parameter Description

pInitData Pointer to a filled USB_IP_INIT_DATA structure data.

377 CHAPTER 12 Target API

12.6.1.2 USBD_IP_Task()

Description

Obsolete. Returns when USB is disconnected.

Prototype

void USBD_IP_Task(void);

378 CHAPTER 12 Target API

12.6.2 Data structures

12.6.2.1 USB_IP_INIT_DATA

Description

Structure which stores the parameters of the IP component.

Type definition

typedef struct {

U8 EPIn;

U8 EPOut;

U8 EPInt;

const USB_IP_NI_DRIVER_API * pDriverAPI;

USB_IP_NI_DRIVER_DATA DriverData;

const USB_RNDIS_DEVICE_INFO * pRndisDevInfo;

} USB_IP_INIT_DATA;

Structure members

Member Description

EPIn Endpoint to send data packets to USB host.

EPOut Endpoint to receive data packets from USB host.

EPInt Endpoint to send notifications to USB host.

pDriverAPI Network interface driver API.

DriverData Data passed at initialization to low-level driver.

pRndisDevInfo Pointer to a filled USB_RNDIS_DEVICE_INFO structure.

Additional information

This structure holds the endpoints that should be used with the IP component. Refer to

USBD_AddEP() for more information about how to add an endpoint.

Chapter 13

Remote NDIS (RNDIS)

This chapter gives a general overview of the Remote Network Driver Interface Specification

class and describes how to get the RNDIS component running on the target.

380 CHAPTER 13 Overview

13.1 Overview

The Remote Network Driver Interface Specification (RNDIS) is a Microsoft proprietary USB

class protocol which can be used to create a virtual Ethernet connection between a USB

device and a host PC. A TCP/IP stack like embOS/IP is required on the USB device side to

handle the actual IP communication. Any available IP protocol (UDP, TPC, FTP, HTTP, etc.)

can be used to exchange data. On a typical Cortex-M CPU running at 120 MHz, a transfer

speed of about 5 MB/s can be achieved when using a high-speed USB connection.

USB RNDIS is supported by all Windows operating systems starting with Windows XP, as

well as by Linux with kernel versions newer than 2.6.34. An .inf file is required for the in-

stallation on Microsoft Windows systems older than Windows 7. The emUSB-Device-RNDIS

package includes .inf files for Windows versions older than Windows 7. OS X will require a

third-party driver to work with RNDIS, which can be downloaded from here: http://joshua-

wise.com/horndis

emUSB-Device-RNDIS contains the following components:

• Generic USB handling

• RNDIS device class implementation

• Network interface driver which uses embOS/IP as TCP/IP stack.

• A sample application demonstrating how to work with RNDIS.

13.1.1 Working with RNDIS

Any USB RNDIS device connected to a PC running the Windows operating system is listed

as a separate network interface in the “Network Connections” window as shown in this

screenshot:

The ping command line utility can be used to test the connection to target as shown below.

If the connection is correctly established the number of the lost packets should be 0.

13.1.2 Additional information

More technical details about RNDIS can be found here:

http://msdn.microsoft.com/en-us/

library/windows/hardware/ff570660%28v=vs.85%29.aspx

381 CHAPTER 13 Configuration

13.2 Configuration

13.2.1 Initial Configuration

To get emUSB-Device-RNDIS up and running as well as doing an initial test, the configu-

ration as delivered should not be modified.

13.2.2 Final configuration

The configuration must only be modified when emUSB-Device is used in your final product.

Refer to section emUSB-Device Configuration on page 41 to get detailed information about

the general emUSB-Device configuration functions which have to be adapted.

13.2.3 Class specific configuration

RNDIS specific device information must be provided by the application via the function USB-

D_RNDIS_SetDeviceInfo() before the USB stack is started using USBD_Start(). A sample

how to use this function can be found in the IP_Config_RNDIS.c. The file is located in the

Sample\RNDIS directory of the emUSB-Device shipment. The IP_Config_RNDIS.c provides

a ready to use layer and configuration file to be used with embOS and embOS/IP.

382 CHAPTER 13 Running the sample application

13.3 Running the sample application

The sample application can be found in the Sample\RNDIS\IP_Config_RNDIS.c file of the

emUSB-Device shipment. In order to use the sample application the SEGGER embOS/IP

middleware component is required. To test the emUSB-Device-RNDIS component any of

the embOS/IP sample applications can be used in combination with IP_Config_RNDIS.c .

After the sample application is started the USB cable should be connected to the PC and

the chosen embOS/IP sample can be tested using the appropriate methods.

13.3.1 IP_Config_RNDIS.c in detail

The main part of the sample application is implemented in the function MainTask() which

runs as an independent task.

// _Connect() - excerpt from IP_Config_RNDIS.c

static int _Connect(unsigned IFaceId) {

U32 Server = IP_BYTES2ADDR(10, 0, 0, 10);

IP_DHCPS_ConfigPool(IFaceId, IP_BYTES2ADDR(10, 0, 0, 11), 0xFF000000, 20);

IP_DHCPS_ConfigDNSAddr(IFaceId, &Server, 1);

IP_DHCPS_Init(IFaceId);

IP_DHCPS_Start(IFaceId);

USBD_Init();

USBD_SetDeviceInfo(&USB_DeviceInfo);

USBD_RNDIS_SetDeviceInfo(&USB_RNDIS_DeviceInfo);

_AddRNDIS();

USBD_Start();

return 0; // Successfully connected.

}

The first step is to initialize the DHCP server component which assigns the IP address for

the PC side. The target is configured with the IP address 10.0.0.10. The DHCP server is

configured to distribute IP addresses starting from 10.0.0.11, therefore the PC will receive

the IP address 10.0.0.11. Then the USB stack is initialized and the RNDIS interface is added

to it. The function _AddRNDIS() configures all required endpoints.

// _AddRNDIS() - excerpt from IP_Config_RNDIS.c

static U8 _abReceiveBuffer[USB_HS_BULK_MAX_PACKET_SIZE];

static void _AddRNDIS(void) {

USB_RNDIS_INIT_DATA InitData;

InitData.EPOut = USBD_AddEP(USB_DIR_OUT,

USB_TRANSFER_TYPE_BULK,

_abReceiveBuffer, sizeof(_abReceiveBuffer));

InitData.EPIn = USBD_AddEP(USB_DIR_IN, USB_TRANSFER_TYPE_BULK,

0, NULL, 0);

InitData.EPInt = USBD_AddEP(USB_DIR_IN, USB_TRANSFER_TYPE_INT,

5, NULL, 0);

InitData.pDriverAPI = &USB_Driver_IP_NI;

InitData.DriverData.pDriverData = (void *)_IFaceId;

USBD_RNDIS_Add(&InitData);

}

The size of _acReceiveBuffer buffer must be a multiple of USB max packet size. USB_Dri-

ver_IP_NI is the network interface driver which implements the connection to the IP stack.

Optionally a HW address may be configured here, which is assigned to the PC network

interface. If not set (pHWAddr = NULL), the HW address is generated automatically later

while setting the interface up.

The IP stack is configured to use the network interface driver of emUSB-Device-RNDIS. For

more information about the configuration of the IP stack refer to embOS/IP manual.

// IP_X_Config() - excerpt from IP_Config.c

#include "USB_Driver_IP_NI.h"

void IP_X_Config(void) {

383 CHAPTER 13 Running the sample application

<...>

// Add and configure the RNDIS driver.

// The local IP address is 10.0.0.10/8.

IFaceId = IP_AddEtherInterface(&USB_IP_Driver);

IP_SetIFaceConnectHook(IFaceId, _Connect);

IP_SetIFaceDisconnectHook(IFaceId, _Disconnect);

_IFaceId = IFaceId;

<...>

}

384 CHAPTER 13 RNDIS + embOS/IP as a "USB Webserver"

13.4 RNDIS + embOS/IP as a "USB Webserver"

This method of using RNDIS provides a unique customer experience where a USB device

can provide a custom web page or any other service through which a customer can interact

with the device.

Initially the PC recognizes an RNDIS device. In case of Windows XP and Vista a driver will be

necessary, Windows 7 and above as well as Linux recognize RNDIS automatically. RNDIS

from the viewpoint of the PC is a normal Network Interface Controller (NIC) and the PC

handles it as such. The default behaviour is to request an IP address from a DHCP server.

The PC retrieves an IP address from the DHCP-Server in the device. In our standard sample

code the device has the local IP 10.0.0.10 and the PC will get 10.0.0.11 from the DHCP

server. With this the configuration is complete and the user can access the web-interface

located on the USB device via 10.0.0.10. To improve the ease-of-use NetBIOS can be used

to give the device an easily readable name.

385 CHAPTER 13 Target API

13.5 Target API

Function Description

API functions

USBD_RNDIS_Add() Adds an RNDIS-class interface to the USB

stack.

USBD_RNDIS_Task() Obsolete.

USBD_RNDIS_SetDeviceInfo() Provides device information used during

USB enumeration to the stack.

Data structures

USB_RNDIS_INIT_DATA Structure which stores the parameters of

the RNDIS interface.

USB_RNDIS_DEVICE_INFO

Device information that must be provid-

ed by the application via the function USB-

D_RNDIS_SetDeviceInfo() before the USB

stack is started using USBD_Start().

USB_IP_NI_DRIVER_API This structure contains the callback func-

tions for the network interface driver.

USB_IP_NI_DRIVER_DATA Configuration data passed to network in-

terface driver at initialization.

386 CHAPTER 13 Target API

13.5.1 API functions

13.5.1.1 USBD_RNDIS_Add()

Description

Adds an RNDIS-class interface to the USB stack.

Prototype

void USBD_RNDIS_Add(const USB_RNDIS_INIT_DATA * pInitData);

Parameters

Parameter Description

pInitData Pointer to initialization data.

Additional information

This function should be called after the initialization of the USB core to add an RNDIS

interface to emUSB-Device. The initialization data is passed to the function in the structure

pointed to by pInitData. Refer to USB_RNDIS_INIT_DATA for more information.

387 CHAPTER 13 Target API

13.5.1.2 USBD_RNDIS_Task()

Description

Obsolete. Returns when USB is disconnected.

Prototype

void USBD_RNDIS_Task(void);

388 CHAPTER 13 Target API

13.5.1.3 USBD_RNDIS_SetDeviceInfo()

Description

Provides device information used during USB enumeration to the stack.

Prototype

void USBD_RNDIS_SetDeviceInfo(const USB_RNDIS_DEVICE_INFO * pDeviceInfo);

Parameters

Parameter Description

pDeviceInfo Pointer to a USB_RNDIS_DEVICE_INFO structure containing

the device information. Must point to static data that is not

changed while the stack is running.

389 CHAPTER 13 Target API

13.5.2 Data structures

13.5.2.1 USB_RNDIS_INIT_DATA

Description

Structure which stores the parameters of the RNDIS interface.

Type definition

typedef struct {

U8 EPIn;

U8 EPOut;

U8 EPInt;

const USB_IP_NI_DRIVER_API * pDriverAPI;

USB_IP_NI_DRIVER_DATA DriverData;

unsigned DataInterfaceNum;

} USB_RNDIS_INIT_DATA;

Structure members

Member Description

EPIn Endpoint for sending data to the host.

EPOut Endpoint for receiving data from the host.

EPInt Endpoint for sending status information.

pDriverAPI Pointer to the Network interface driver API.

DriverData Configuration data for the network interface driver.

DataInterfaceNum Internal use

Additional information

This structure holds the endpoints that should be used by the RNDIS interface (EPin, EPOut

and EPInt). Refer to USBD_AddEP() for more information about how to add an endpoint.

390 CHAPTER 13 Target API

13.5.2.2 USB_RNDIS_DEVICE_INFO

Description

Device information that must be provided by the application via the function USB-

D_RNDIS_SetDeviceInfo() before the USB stack is started using USBD_Start().

Type definition

typedef struct {

U32 VendorId;

char * sDescription;

U16 DriverVersion;

} USB_RNDIS_DEVICE_INFO;

Structure members

Member Description

VendorId

A 24-bit Organizationally Unique Identifier (OUI) of the ven-

dor. This is the same value as the one stored in the first 3

bytes of a HW (MAC) address. Only the least significant 24

bits of the retuned value are used.

sDescription 0-terminated ASCII string describing the device. The string

is then sent to the host system.

DriverVersion 16-bit value representing the firmware version. The high-or-

der byte specifies the major version and the low-order byte

the minor version.

391 CHAPTER 13 Target API

13.5.3 Driver interface

13.5.3.1 USB_IP_NI_DRIVER_API

Description

This structure contains the callback functions for the network interface driver.

Type definition

typedef struct {

USB_IP_NI_INIT * pfInit;

USB_IP_NI_GET_PACKET_BUFFER * pfGetPacketBuffer;

USB_IP_NI_WRITE_PACKET * pfWritePacket;

USB_IP_NI_SET_PACKET_FILTER * pfSetPacketFilter;

USB_IP_NI_GET_LINK_STATUS * pfGetLinkStatus;

USB_IP_NI_GET_LINK_SPEED * pfGetLinkSpeed;

USB_IP_NI_GET_HWADDR * pfGetHWAddr;

USB_IP_NI_GET_STATS * pfGetStats;

USB_IP_NI_GET_MTU * pfGetMTU;

USB_IP_NI_RESET * pfReset;

USB_IP_NI_SET_WRITE_PACKET_FUNC * pfSetWritePacketFunc;

} USB_IP_NI_DRIVER_API;

Structure members

Member Description

pfInit Initializes the driver.

pfGetPacketBuffer Returns a buffer for a data packet.

pfWritePacket Delivers a data packet to target IP stack.

pfSetPacketFilter Configures the type of accepted data packets.

pfGetLinkStatus Returns the status of the connection to target IP stack.

pfGetLinkSpeed Returns the connection speed.

pfGetHWAddr Returns the HW address of the PC.

pfGetStats Returns statistical counters.

pfGetMTU Returns the size of the largest data packet which can be

transferred.

pfReset Resets the driver.

pfSetWritePacketFunc Allows to change the WritePacket callback which was set by

pfInit.

Additional information

The emUSB-Device-RNDIS/emUSB-Device-CDC-ECM component calls the functions of this

API to exchange data and status information with the IP stack running on the target.

392 CHAPTER 13 Target API

13.5.3.2 USB_IP_NI_DRIVER_DATA

Description

Configuration data passed to network interface driver at initialization.

Type definition

typedef struct {

const U8 * pHWAddr;

unsigned NumBytesHWAddr;

void * pDriverData;

} USB_IP_NI_DRIVER_DATA;

Structure members

Member Description

pHWAddr Optional pointer to a HW address (or MAC address) of the

host network interface.

NumBytesHWAddr Number of bytes in the HW address. Typically 6 bytes.

pDriverData Pointer to a user context.

Additional information

When pHWAddr is NULL the MAC is automatically generated.

393 CHAPTER 13 RNDIS IP Driver

13.6 RNDIS IP Driver

This section describes the emUSB-Device RNDIS IP stack interface in detail.

13.6.1 General information

This release comes with IP NI driver which uses embOS/IP as the IP stack. If you are using

embOS/IP this chapter can be ignored. This chapter is for those who wish to write their

own IP stack interface for a third-party IP stack.

The IP interface is handled through an API-table, which contains all relevant functions

necessary for read/write operations and initialization.

13.6.2 Interface function list

As described above, access to network functions is realized through an API-function table

of type USB_IP_NI_DRIVER_API. The structure is declared in USB_Driver_IP_NI.h and it is

described in section Data structures on page 389

394 CHAPTER 13 RNDIS IP Driver

13.6.3 USB_IP_NI_DRIVER_API in detail

13.6.3.1 USB_IP_NI_INIT

Description

Initializes the driver.

Type definition

typedef unsigned (USB_IP_NI_INIT)(const USB_IP_NI_DRIVER_DATA * pDriverData,

USB_IP_WRITE_PACKET * pfWritePacket);

Parameters

Parameter Description

pDriverData in Pointer to driver configuration data.

pfWritePacket Call back function called by the IP stack to transmit a packet

that should be send to the USB host.

Return value

IP NI driver instance ID.

Additional information

This function is called when the RNDIS/ECM interface is added to the USB stack. Typically

the function makes a local copy of the HW address passed in the pDriverData structure.

For more information this structure refer to USB_IP_NI_DRIVER_DATA.

395 CHAPTER 13 RNDIS IP Driver

13.6.3.2 USB_IP_NI_GET_PACKET_BUFFER

Description

Returns a buffer for a data packet.

Type definition

typedef void * (USB_IP_NI_GET_PACKET_BUFFER)(unsigned Id,

unsigned NumBytes);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

NumBytes Size of the requested buffer in bytes.

Return value

≠ NULL Pointer to allocated buffer

= NULL No buffer available

Additional information

The function should allocate a buffer of the requested size. If the buffer can not be allocated

a NULL pointer should be returned. The function is called when a data packet is received

from PC. The packet data is stored in the returned buffer.

396 CHAPTER 13 RNDIS IP Driver

13.6.3.3 USB_IP_NI_WRITE_PACKET

Description

Delivers a data packet to target IP stack.

Type definition

typedef void (USB_IP_NI_WRITE_PACKET)( unsigned Id,

const void * pData,

unsigned NumBytes);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

pData in Data of the received packet.

NumBytes Number of bytes stored in the buffer.

Additional information

The function is called after a data packet has been received from USB. pData points to the

buffer returned by the USB_IP_NI_GET_PACKET_BUFFER function.

397 CHAPTER 13 RNDIS IP Driver

13.6.3.4 USB_IP_NI_SET_PACKET_FILTER

Description

Configures the type of accepted data packets.

Type definition

typedef void (USB_IP_NI_SET_PACKET_FILTER)(unsigned Id,

U32 Mask);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

Mask Type of accepted data packets.

Additional information

The Mask parameter should be interpreted as a boolean value. A value different than 0

indicates that the connection to target IP stack should be established. When the function

is called with the Mask parameter set to 0 the connection to target IP stack should be

interrupted.

398 CHAPTER 13 RNDIS IP Driver

13.6.3.5 USB_IP_NI_GET_LINK_STATUS

Description

Returns the status of the connection to target IP stack.

Type definition

typedef int (USB_IP_NI_GET_LINK_STATUS)(unsigned Id);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

Return value

USB_IP_NI_LINK_STATUS_DISCONNECTED Connected to target IP stack.

USB_IP_NI_LINK_STATUS_CONNECTED Not connected to target IP stack.

399 CHAPTER 13 RNDIS IP Driver

13.6.3.6 USB_IP_NI_GET_LINK_SPEED

Description

Returns the connection speed.

Type definition

typedef U32 (USB_IP_NI_GET_LINK_SPEED)(unsigned Id);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

Return value

≠ 0 The connection speed in units of 100 bits/sec.

= 0 Not connected.

400 CHAPTER 13 RNDIS IP Driver

13.6.3.7 USB_IP_NI_GET_HWADDR

Description

Returns the HW address of the host network interface (PC).

Type definition

typedef void (USB_IP_NI_GET_HWADDR)(unsigned Id,

U8 * pAddr,

unsigned NumBytes);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

pAddr out The HW address.

NumBytes Maximum number of bytes to store into pAddr.

Additional information

The returned HW address is the one passed to the driver in the call to USB_IP_NI_INIT.

Typically the HW address is 6 bytes long.

401 CHAPTER 13 RNDIS IP Driver

13.6.3.8 USB_IP_NI_GET_STATS

Description

Returns statistical counters.

Type definition

typedef U32 (USB_IP_NI_GET_STATS)(unsigned Id,

int Type);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

Type The type of information requested. See table below.

Return value

Value of the requested statistical counter.

Additional information

The counters should be set to 0 when the USB_IP_NI_RESET function is called.

Permitted values for parameter Type

USB_IP_NI_STATS_WRITE_PACKET_OK Number of packets sent without errors

to target IP stack.

USB_IP_NI_STATS_WRITE_PACKET_ERROR Number of packets sent with errors to

target IP stack.

USB_IP_NI_STATS_READ_PACKET_OK Number of packets received without

errors from target IP stack.

USB_IP_NI_STATS_READ_PACKET_ERROR Number of packets received with er-

rors from target IP stack.

USB_IP_NI_STATS_READ_NO_BUFFER Number of packets received from tar-

get IP stack but dropped.

USB_IP_NI_STATS_READ_ALIGN_ERROR Number of packets received from tar-

get IP stack with alignment errors.

USB_IP_NI_STATS_WRITE_ONE_COLLISION Number of packets which were not

sent to target IP stack due to the oc-

currence of one collision.

USB_IP_NI_STATS_WRITE_MORE_COLLISIONS Number of packets which were not

sent to target IP stack due to the oc-

currence of one or more collisions.

402 CHAPTER 13 RNDIS IP Driver

13.6.3.9 USB_IP_NI_GET_MTU

Description

Returns the maximum transmission unit, the size of the largest data packet which can be

transferred.

Type definition

typedef U32 (USB_IP_NI_GET_MTU)(unsigned Id);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

Return value

The MTU size in bytes. Typically 1500 bytes.

403 CHAPTER 13 RNDIS IP Driver

13.6.3.10 USB_IP_NI_RESET

Description

Resets the driver.

Type definition

typedef void (USB_IP_NI_RESET)(unsigned Id);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

404 CHAPTER 13 RNDIS IP Driver

13.6.3.11 USB_IP_NI_SET_WRITE_PACKET_FUNC

Description

Changes the USB_IP_WRITE_PACKET callback which was added via USB_IP_NI_INIT to a

different callback function. This function is only called by the stack when USB Ethernet is

used. It is not called when RNDIS or ECM is used standalone.

Type definition

typedef void (USB_IP_NI_SET_WRITE_PACKET_FUNC)

(unsigned Id,

USB_IP_WRITE_PACKET * pfWritePacket);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

pfWritePacket Call back function called by the IP stack to transmit a packet

that should be send to the USB host.

Chapter 14

CDC-ECM

This chapter gives a general overview of the Communications Device Class / Ethernet Con-

trol Model class and describes how to get the ECM component running on the target.

406 CHAPTER 14 Overview

14.1 Overview

The Communications Device Class / Ethernet Control Model is a USB class protocol of the

USB Implementers Forum which can be used to create a virtual Ethernet connection be-

tween a USB device and a host PC. A TCP/IP stack like embOS/IP is required on the USB

device side to handle the actual IP communication. Any available IP protocol (UDP, TPC,

FTP, HTTP, etc.) can be used to exchange data.

USB ECM is supported by the Linux operating system. To use it on Windows, a third party

driver (not contained in emUSB-Device-ECM) has to be installed on the Windows system.

emUSB-Device-ECM contains the following components:

• Generic USB handling

• ECM device class implementation

• Network interface driver which uses embOS/IP as TCP/IP stack.

• A sample application demonstrating how to work with ECM.

14.1.1 Working with CDC-ECM

Any USB ECM device connected to a PC running the Windows operating system is listed

as a separate network interface in the “Network Connections” window as shown in this

screenshot:

The ping command line utility can be used to test the connection to target as shown below.

If the connection is correctly established the number of the lost packets should be 0. The

following screenshot shows a manual configuration and ping on Linux.

407 CHAPTER 14 Overview

14.1.2 Additional information

More technical details about CDC-ECM can be found here:

http://www.usb.org/developers/docs/devclass_docs/CDC1.2_WMC1.1_052013.zip

408 CHAPTER 14 Configuration

14.2 Configuration

14.2.1 Initial configuration

To get emUSB-Device-ECM up and running as well as doing an initial test, the configuration

as delivered should not be modified. When using on Windows with a third party driver, the

vendor id and product id must match the ids configured in the .inf file of the driver.

14.2.2 Final configuration

The configuration must only be modified when emUSB-Device is used in your final product.

Refer to section emUSB-Device Configuration on page 41 to get detailed information about

the general emUSB-Device configuration functions which have to be adapted.

409 CHAPTER 14 Running the sample application

14.3 Running the sample application

The sample application can be found in the Sample\ECM\IP_Config_ECM.c file of the

emUSB-Device shipment. In order to use the sample application the SEGGER embOS/IP

middleware component is required. To test the emUSB-Device-ECM component any of the

embOS/IP sample applications can be used in combination with IP_Config_ECM.c. After

the sample application is started the USB cable should be connected to the PC and the

chosen embOS/IP sample can be tested using the appropriate methods.

14.3.1 IP_Config_ECM.c in detail

The main part of the sample application is implemented in the function MainTask() which

runs as an independent task.

// _Connect() - excerpt from IP_Config_ECM.c

static int _Connect(unsigned IFaceId) {

U32 Server = IP_BYTES2ADDR(10, 0, 0, 10);

IP_DHCPS_ConfigPool(IFaceId, IP_BYTES2ADDR(10, 0, 0, 11), 0xFF000000, 20);

IP_DHCPS_ConfigDNSAddr(IFaceId, &Server, 1);

IP_DHCPS_Init(IFaceId);

IP_DHCPS_Start(IFaceId);

USBD_Init();

USBD_SetDeviceInfo(&USB_DeviceInfo);

_AddECM();

USBD_Start();

return 0; // Successfully connected.

}

The first step is to initialize the DHCP server component which assigns the IP address for

the PC side. The target is configured with the IP address 10.0.0.10. The DHCP server is

configured to distribute IP addresses starting from 10.0.0.11, therefore the PC will receive

the IP address 10.0.0.11. Then the USB stack is initialized and the ECM interface is added to

it. The function _AddECM() configures all required endpoints and configures the HW address

of the PC network interface.

// _AddECM() - excerpt from IP_Config_ECM.c

static U8 _abReceiveBuffer[USB_HS_BULK_MAX_PACKET_SIZE];

static void _AddECM(void) {

USB_ECM_INIT_DATA InitData;

InitData.EPOut = USBD_AddEP(USB_DIR_OUT,

USB_TRANSFER_TYPE_BULK,

_abReceiveBuffer, sizeof(_abReceiveBuffer));

InitData.EPIn = USBD_AddEP(USB_DIR_IN, USB_TRANSFER_TYPE_BULK,

0, NULL, 0);

InitData.EPInt = USBD_AddEP(USB_DIR_IN, USB_TRANSFER_TYPE_INT,

32, NULL, 0);

InitData.pDriverAPI = &USB_Driver_IP_NI;

InitData.DriverData.pDriverData = (void *)_IFaceId;

#if 0

InitData.DriverData.pHWAddr = "\x00\x22\xC7\xFF\xFF\xF3";

InitData.DriverData.NumBytesHWAddr = 6;

#endif

USBD_ECM_Add(&InitData);

}

The size of _acReceiveBuffer buffer must be a multiple of USB max packet size. USB_Dri-

ver_IP_NI is the network interface driver which implements the connection to the IP stack.

Optionally a HW address may be configured here, which is assigned to the PC network

interface. If not set (pHWAddr = NULL), the HW address is generated automatically later

while setting the interface up.

The IP stack is configured to use the network interface driver of emUSB-Device-ECM. For

more information about the configuration of the IP stack refer to embOS/IP manual.

410 CHAPTER 14 Running the sample application

// IP_X_Config() - excerpt from IP_Config.c

#include "USB_Driver_IP_NI.h"

void IP_X_Config(void) {

<...>

// Add and configure the ECM driver.

// The local IP address is 10.0.0.10/8.

IFaceId = IP_AddEtherInterface(&USB_IP_Driver);

IP_SetAddrMask(0x0A00000A, 0xFF000000);

IP_SetIFaceConnectHook(IFaceId, _Connect);

IP_SetIFaceDisconnectHook(IFaceId, _Disconnect);

_IFaceId = IFaceId;

<...>

}

411 CHAPTER 14 Target API

14.4 Target API

Function Description

API functions

USBD_ECM_Add() Adds an ECM-class interface to the USB

stack.

USBD_ECM_Task() Obsolete.

Data structures

USB_ECM_INIT_DATA Initialization data for ECM interface.

USB_IP_NI_DRIVER_API This structure contains the callback func-

tions for the network interface driver.

USB_IP_NI_DRIVER_DATA Configuration data passed to network in-

terface driver at initialization.

412 CHAPTER 14 Target API

14.4.1 API functions

14.4.1.1 USBD_ECM_Add()

Description

Adds an ECM-class interface to the USB stack.

Prototype

void USBD_ECM_Add(const USB_ECM_INIT_DATA * pInitData);

Parameters

Parameter Description

pInitData Pointer to a USB_ECM_INIT_DATA structure.

Additional information

This function should be called after the initialization of the USB core to add an ECM interface

to emUSB-Device. The initialization data is passed to the function in the structure pointed

to by pInitData. Refer to USB_ECM_INIT_DATA for more information.

413 CHAPTER 14 Target API

14.4.1.2 USBD_ECM_Task()

Description

Obsolete. Returns when USB is disconnected.

Prototype

void USBD_ECM_Task(void);

414 CHAPTER 14 Target API

14.4.2 Data structures

14.4.2.1 USB_ECM_INIT_DATA

Description

Initialization data for ECM interface.

Type definition

typedef struct {

U8 EPIn;

U8 EPOut;

U8 EPInt;

const USB_IP_NI_DRIVER_API * pDriverAPI;

USB_IP_NI_DRIVER_DATA DriverData;

unsigned DataInterfaceNum;

} USB_ECM_INIT_DATA;

Structure members

Member Description

EPIn Endpoint for sending data to the host.

EPOut Endpoint for receiving data from the host. The buffer associ-

ated to this endpoint must be big enough to hold a complete

IP packet.

EPInt Endpoint for sending status information.

pDriverAPI Pointer to the Network interface driver API. See

USB_IP_NI_DRIVER_API.

DriverData Configuration data for the network interface driver.

DataInterfaceNum Internal use.

Additional information

This structure holds the endpoints that should be used by the ECM interface (EPin, EPOut

and EPInt). Refer to USBD_AddEP() for more information about how to add an endpoint.

415 CHAPTER 14 Target API

14.4.3 Driver interface

14.4.3.1 USB_IP_NI_DRIVER_API

Description

This structure contains the callback functions for the network interface driver.

Type definition

typedef struct {

USB_IP_NI_INIT * pfInit;

USB_IP_NI_GET_PACKET_BUFFER * pfGetPacketBuffer;

USB_IP_NI_WRITE_PACKET * pfWritePacket;

USB_IP_NI_SET_PACKET_FILTER * pfSetPacketFilter;

USB_IP_NI_GET_LINK_STATUS * pfGetLinkStatus;

USB_IP_NI_GET_LINK_SPEED * pfGetLinkSpeed;

USB_IP_NI_GET_HWADDR * pfGetHWAddr;

USB_IP_NI_GET_STATS * pfGetStats;

USB_IP_NI_GET_MTU * pfGetMTU;

USB_IP_NI_RESET * pfReset;

USB_IP_NI_SET_WRITE_PACKET_FUNC * pfSetWritePacketFunc;

} USB_IP_NI_DRIVER_API;

Structure members

Member Description

pfInit Initializes the driver.

pfGetPacketBuffer Returns a buffer for a data packet.

pfWritePacket Delivers a data packet to target IP stack.

pfSetPacketFilter Configures the type of accepted data packets.

pfGetLinkStatus Returns the status of the connection to target IP stack.

pfGetLinkSpeed Returns the connection speed.

pfGetHWAddr Returns the HW address of the PC.

pfGetStats Returns statistical counters.

pfGetMTU Returns the size of the largest data packet which can be

transferred.

pfReset Resets the driver.

pfSetWritePacketFunc Allows to change the WritePacket callback which was set by

pfInit.

Additional information

The emUSB-Device-RNDIS/emUSB-Device-CDC-ECM component calls the functions of this

API to exchange data and status information with the IP stack running on the target.

416 CHAPTER 14 Target API

14.4.3.2 USB_IP_NI_DRIVER_DATA

Description

Configuration data passed to network interface driver at initialization.

Type definition

typedef struct {

const U8 * pHWAddr;

unsigned NumBytesHWAddr;

void * pDriverData;

} USB_IP_NI_DRIVER_DATA;

Structure members

Member Description

pHWAddr Optional pointer to a HW address (or MAC address) of the

host network interface.

NumBytesHWAddr Number of bytes in the HW address. Typically 6 bytes.

pDriverData Pointer to a user context.

Additional information

When pHWAddr is NULL the MAC is automatically generated.

417 CHAPTER 14 CDC-ECM IP Driver

14.5 CDC-ECM IP Driver

This section describes the emUSB-Device CDC-ECM IP stack interface in detail.

14.5.1 General information

This release comes with IP NI driver which uses embOS/IP as the IP stack. If you are using

embOS/IP this chapter can be ignored. This chapter is for those who wish to write their

own IP stack interface for a third-party IP stack.

The IP interface is handled through an API-table, which contains all relevant functions

necessary for read/write operations and initialization.

14.5.2 Interface function list

As described above, access to network functions is realized through an API-function table

of type USB_IP_NI_DRIVER_API. The structure is declared in USB_Driver_IP_NI.h and it is

described in section Data structures on page 414

418 CHAPTER 14 CDC-ECM IP Driver

14.5.3 USB_IP_NI_DRIVER_API in detail

14.5.3.1 USB_IP_NI_INIT

Description

Initializes the driver.

Type definition

typedef unsigned (USB_IP_NI_INIT)(const USB_IP_NI_DRIVER_DATA * pDriverData,

USB_IP_WRITE_PACKET * pfWritePacket);

Parameters

Parameter Description

pDriverData in Pointer to driver configuration data.

pfWritePacket Call back function called by the IP stack to transmit a packet

that should be send to the USB host.

Return value

IP NI driver instance ID.

Additional information

This function is called when the RNDIS/ECM interface is added to the USB stack. Typically

the function makes a local copy of the HW address passed in the pDriverData structure.

For more information this structure refer to USB_IP_NI_DRIVER_DATA.

419 CHAPTER 14 CDC-ECM IP Driver

14.5.3.2 USB_IP_NI_GET_PACKET_BUFFER

Description

Returns a buffer for a data packet.

Type definition

typedef void * (USB_IP_NI_GET_PACKET_BUFFER)(unsigned Id,

unsigned NumBytes);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

NumBytes Size of the requested buffer in bytes.

Return value

≠ NULL Pointer to allocated buffer

= NULL No buffer available

Additional information

The function should allocate a buffer of the requested size. If the buffer can not be allocated

a NULL pointer should be returned. The function is called when a data packet is received

from PC. The packet data is stored in the returned buffer.

420 CHAPTER 14 CDC-ECM IP Driver

14.5.3.3 USB_IP_NI_WRITE_PACKET

Description

Delivers a data packet to target IP stack.

Type definition

typedef void (USB_IP_NI_WRITE_PACKET)( unsigned Id,

const void * pData,

unsigned NumBytes);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

pData in Data of the received packet.

NumBytes Number of bytes stored in the buffer.

Additional information

The function is called after a data packet has been received from USB. pData points to the

buffer returned by the USB_IP_NI_GET_PACKET_BUFFER function.

421 CHAPTER 14 CDC-ECM IP Driver

14.5.3.4 USB_IP_NI_SET_PACKET_FILTER

Description

Configures the type of accepted data packets.

Type definition

typedef void (USB_IP_NI_SET_PACKET_FILTER)(unsigned Id,

U32 Mask);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

Mask Type of accepted data packets.

Additional information

The Mask parameter should be interpreted as a boolean value. A value different than 0

indicates that the connection to target IP stack should be established. When the function

is called with the Mask parameter set to 0 the connection to target IP stack should be

interrupted.

422 CHAPTER 14 CDC-ECM IP Driver

14.5.3.5 USB_IP_NI_GET_LINK_STATUS

Description

Returns the status of the connection to target IP stack.

Type definition

typedef int (USB_IP_NI_GET_LINK_STATUS)(unsigned Id);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

Return value

USB_IP_NI_LINK_STATUS_DISCONNECTED Connected to target IP stack.

USB_IP_NI_LINK_STATUS_CONNECTED Not connected to target IP stack.

423 CHAPTER 14 CDC-ECM IP Driver

14.5.3.6 USB_IP_NI_GET_LINK_SPEED

Description

Returns the connection speed.

Type definition

typedef U32 (USB_IP_NI_GET_LINK_SPEED)(unsigned Id);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

Return value

≠ 0 The connection speed in units of 100 bits/sec.

= 0 Not connected.

424 CHAPTER 14 CDC-ECM IP Driver

14.5.3.7 USB_IP_NI_GET_HWADDR

Description

Returns the HW address of the host network interface (PC).

Type definition

typedef void (USB_IP_NI_GET_HWADDR)(unsigned Id,

U8 * pAddr,

unsigned NumBytes);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

pAddr out The HW address.

NumBytes Maximum number of bytes to store into pAddr.

Additional information

The returned HW address is the one passed to the driver in the call to USB_IP_NI_INIT.

Typically the HW address is 6 bytes long.

425 CHAPTER 14 CDC-ECM IP Driver

14.5.3.8 USB_IP_NI_GET_STATS

Description

Returns statistical counters.

Type definition

typedef U32 (USB_IP_NI_GET_STATS)(unsigned Id,

int Type);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

Type The type of information requested. See table below.

Return value

Value of the requested statistical counter.

Additional information

The counters should be set to 0 when the USB_IP_NI_RESET function is called.

Permitted values for parameter Type

USB_IP_NI_STATS_WRITE_PACKET_OK Number of packets sent without errors

to target IP stack.

USB_IP_NI_STATS_WRITE_PACKET_ERROR Number of packets sent with errors to

target IP stack.

USB_IP_NI_STATS_READ_PACKET_OK Number of packets received without

errors from target IP stack.

USB_IP_NI_STATS_READ_PACKET_ERROR Number of packets received with er-

rors from target IP stack.

USB_IP_NI_STATS_READ_NO_BUFFER Number of packets received from tar-

get IP stack but dropped.

USB_IP_NI_STATS_READ_ALIGN_ERROR Number of packets received from tar-

get IP stack with alignment errors.

USB_IP_NI_STATS_WRITE_ONE_COLLISION Number of packets which were not

sent to target IP stack due to the oc-

currence of one collision.

USB_IP_NI_STATS_WRITE_MORE_COLLISIONS Number of packets which were not

sent to target IP stack due to the oc-

currence of one or more collisions.

426 CHAPTER 14 CDC-ECM IP Driver

14.5.3.9 USB_IP_NI_GET_MTU

Description

Returns the maximum transmission unit, the size of the largest data packet which can be

transferred.

Type definition

typedef U32 (USB_IP_NI_GET_MTU)(unsigned Id);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

Return value

The MTU size in bytes. Typically 1500 bytes.

427 CHAPTER 14 CDC-ECM IP Driver

14.5.3.10 USB_IP_NI_RESET

Description

Resets the driver.

Type definition

typedef void (USB_IP_NI_RESET)(unsigned Id);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

428 CHAPTER 14 CDC-ECM IP Driver

14.5.3.11 USB_IP_NI_SET_WRITE_PACKET_FUNC

Description

Changes the USB_IP_WRITE_PACKET callback which was added via USB_IP_NI_INIT to a

different callback function. This function is only called by the stack when USB Ethernet is

used. It is not called when RNDIS or ECM is used standalone.

Type definition

typedef void (USB_IP_NI_SET_WRITE_PACKET_FUNC)

(unsigned Id,

USB_IP_WRITE_PACKET * pfWritePacket);

Parameters

Parameter Description

Id Instance ID returned from USB_IP_NI_INIT.

pfWritePacket Call back function called by the IP stack to transmit a packet

that should be send to the USB host.

Chapter 15

Audio

This chapter gives a general overview of the Audio class and describes how to get the Audio

component running on the target.

430 CHAPTER 15 Overview

15.1 Overview

The USB Audio device class is a USB class protocol which can be used to transfer sound

data from a device to a host and vice versa.

Audio is supported by most operating systems out of the box and the installation of addi-

tional drivers is not required.

emUSB-Device-Audio comes as a complete package and contains the following:

• Generic USB handling

• USB Audio V1 device class implementation

• Sample application showing how to work with Audio

431 CHAPTER 15 Introduction

15.2 Introduction

SEGGER’s implementation of the Audio class V1.0 is designed with minimal resource usage

in mind, especially targeted to embedded devices. The implementation supports the usage

of a “speaker” (input/output audio terminal with a feature terminal for controls) and a

“microphone” (input/output audio terminal).

The speaker and microphone can be used independently of each other, both can be enabled

at the same time allowing audio transfer in either direction.

The Audio class supports no synchronization, commands SET_CUR, GET_CUR, SET_MIN,

GET_MIN, SET_MAX, GET_MAX, SET_RES, GET_RES, for the speaker interface feature unit con-

trols are supported (volume, mute, etc.).

Note

emUSB-Device-Audio does not provide drivers/codecs for any audio peripherals, writ-

ing a driver to interface with the audio hardware is the responsibility of the customer.

With emUSB-Device-Audio Audio data is transfered in the PCM encoding. The Audio class

transfers multiple audio samples in a single packet. In the following sample the audio class

is configured with 2 channels (stereo) and 16 bit data per channel:

The length of a complete audio packet is equal to the bits per sample roundet up to bytes,

multiplied by the number of channels and the sample rate, then divided by 1000 as a packet

is sent every millisecond. For a sample rate of 48000, 16 bits per sample, 2 channels the

calculation is as follows:

48000 * 16/8 * 2 / 1000 = 192 bytes

For a sample rate of 44100, 16 bits per sample, 2 channels the calculation is as follows:

44100 * 16/8 * 2 / 1000 = 176.4 bytes

Since we can not transfer 0.4 bytes the audio packets need to be 176 bytes (44 samples)

and each 10th packet (sample size divided by the remainder: 4 / 0.4) should contain 45

samples (180 bytes) to make sure the sample rate remains at 44100.

432 CHAPTER 15 Configuration

15.3 Configuration

15.3.1 Initial configuration

To get emUSB-Device-Audio up and running as well as doing an initial test, the configuration

as delivered with the sample application should not be modified.

15.3.2 Final configuration

The configuration must only be modified when emUSB-Device is integrated in your final

product. Refer to section emUSB-Device Configuration on page 41 for detailed information

about the generic information functions which have to be adapted.

15.3.3 Using the microphone interface

When using the microphone sample applications with a PC it is not immediately clear

whether they work as the PC only receives the audio data. To listen to the data being sent

from the target running emUSB-Device-Audio to your PC it is necessary to enable a loop-

back mode which will transfer the audio data from the microphone interface to the physical

speakers connected to your PC.

Linux

This guide assumes you are using pulse audio.

• Make sure the device running emUSB-Device-Audio microphone sample is selected as

the default sound input device.

• Make sure your speakers (or headphones) are selected as the default sound output

device.

• Run pactl load-module module-loopback to enable loopback.

• At this point your should hear the sound being produced by the microphone sample.

• You can run pactl unload-module module-loopback to disable the loopback mode.

Windows

• Make sure your speakers (or headphones) are selected as the default sound output

device.

• In the sound configuration of the device running emUSB-Device-Audio microphone

sample tick the “Listen to this device” checkbox and click “Apply”.

• At this point your should hear the sound being produced by the microphone sample.

433 CHAPTER 15 Configuration

Mac

At the time of writing no built-in way of looping back audio is known. But there are a couple

of third party applications out there which can enable loopback mode for macOS.

15.3.4 Using the speaker interface

When using the speaker sample applications the PC merely needs to be configured to use

the device running emUSB-Device-Audio as the default output sound device.

434 CHAPTER 15 Target API

15.4 Target API

Function Description

API functions

USBD_AUDIO_Add() Adds an Audio interface to the USB stack.

USBD_AUDIO_Read_Task() Task function of the Audio component

which processes data received from host.

USBD_AUDIO_Write_Task() Task function of the Audio component

which processes data sent to the host.

USBD_AUDIO_Start_Play() Starts providing audio data to the host us-

ing the microphone terminal of the audio

class.

USBD_AUDIO_Stop_Play() Stops providing audio data to the host.

USBD_AUDIO_Start_Listen() Starts receiving audio data from the host

using the speaker terminal of the audio

class.

USBD_AUDIO_Stop_Listen() Stops receiving audio data from the host.

Data structures

USBD_AUDIO_INIT_DATA Initialization data for the Audio interface.

USBD_AUDIO_MIC_CONF Initialization data for the microphone inter-

face.

USBD_AUDIO_SPEAKER_CONF Initialization data for the speaker inter-

face.

Function definitions

USBD_AUDIO_TX_FUNC Definition of the callback which is called

when audio data is sent.

USBD_AUDIO_RX_FUNC Definition of the callback which is called

when audio data is received.

USBD_AUDIO_CONTROL_FUNC Definition of the callback which is called

when audio commands are received.

435 CHAPTER 15 Target API

15.4.1 API functions

15.4.1.1 USBD_AUDIO_Add()

Description

Adds an Audio interface to the USB stack.

Prototype

USBD_AUDIO_HANDLE USBD_AUDIO_Add(const USBD_AUDIO_INIT_DATA * pInitData);

Parameters

Parameter Description

pInitData Pointer to a USBD_AUDIO_INIT_DATA structure containing val-

ues for the initialization.

Return value

USBD_AUDIO_HANDLE - Handle for the added Audio instance.

Additional information

After the initialization of USB core, this is the first function that needs to be called when

an Audio interface is used with emUSB-Device. The structure USBD_AUDIO_INIT_DATA has

to be initialized before USBD_AUDIO_Add() is called. Refer to USBD_AUDIO_INIT_DATA for

more information.

For the Audio component to be functional one or both of the following functions have to be

created as a task: USBD_AUDIO_Read_Task(), USBD_AUDIO_Write_Task().

436 CHAPTER 15 Target API

15.4.1.2 USBD_AUDIO_Read_Task()

Description

Task function of the Audio component which processes data received from host. Handles

operations of the speaker interface. Has to be created as a separate task.

Prototype

void USBD_AUDIO_Read_Task(void);

Additional information

Only necessary if the speaker interface is used. The function returns only when USB-

D_DeInit() is called.

437 CHAPTER 15 Target API

15.4.1.3 USBD_AUDIO_Write_Task()

Description

Task function of the Audio component which processes data sent to the host. Handles

operations of the microphone interface. Has to be created as a separate task.

Prototype

void USBD_AUDIO_Write_Task(void);

Additional information

Only necessary if the microphone interface is used. The function returns only when USB-

D_DeInit() is called.

438 CHAPTER 15 Target API

15.4.1.4 USBD_AUDIO_Start_Play()

Description

Starts providing audio data to the host using the microphone terminal of the audio class.

Prototype

int USBD_AUDIO_Start_Play(USBD_AUDIO_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to a valid Audio instance, returned by USBD_AU-

DIO_Add().

Return value

= 0 Success.

< 0 An error occurred.

Additional information

This function starts the initial transfer after which the registered TX callback ( USBD_AU-

DIO_TX_FUNC ) is called. The callback is called after every successful transfer and should

move the buffer pointer to the next audio packet accordingly or fill the same buffer with new

data. The callback is called in an interrupt context. The execution of the callback together

with the internal routines must never take longer than 1 millisecond.

439 CHAPTER 15 Target API

15.4.1.5 USBD_AUDIO_Stop_Play()

Description

Stops providing audio data to the host.

Prototype

void USBD_AUDIO_Stop_Play(USBD_AUDIO_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to a valid Audio instance, returned by USBD_AU-

DIO_Add().

440 CHAPTER 15 Target API

15.4.1.6 USBD_AUDIO_Start_Listen()

Description

Starts receiving audio data from the host using the speaker terminal of the audio class.

Prototype

int USBD_AUDIO_Start_Listen(USBD_AUDIO_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to a valid Audio instance, returned by USBD_AU-

DIO_Add().

Return value

= 0 Success.

< 0 An error occurred.

Additional information

This function enables the registered callback function ( USBD_AUDIO_RX_FUNC ) which is

called before the host sends data to the target. Inside the callback you may read the

received data. The callback is called in an interrupt context. The execution of the callback

together with the internal routines must never take longer than 1 millisecond.

441 CHAPTER 15 Target API

15.4.1.7 USBD_AUDIO_Stop_Listen()

Description

Stops receiving audio data from the host.

Prototype

void USBD_AUDIO_Stop_Listen(USBD_AUDIO_HANDLE hInst);

Parameters

Parameter Description

hInst Handle to a valid Audio instance, returned by USBD_AU-

DIO_Add().

442 CHAPTER 15 Target API

15.4.2 Data structures

15.4.2.1 USBD_AUDIO_INIT_DATA

Description

Initialization data for the Audio interface.

Type definition

typedef struct {

U8 EPIn;

U8 EPOut;

U8 * pBufOut;

const U8 * pBufIn;

unsigned InPacketSize;

unsigned OutPacketSize;

USBD_AUDIO_RX_FUNC * pfOnOut;

USBD_AUDIO_TX_FUNC * pfOnIn;

USBD_AUDIO_CONTROL_FUNC * pfOnControl;

void * pControlUserContext;

const USBD_AUDIO_MIC_CONF * pMicConf;

const USBD_AUDIO_SPEAKER_CONF * pSpeakerConf;

int ReadTimeout;

int WriteTimeout;

} USBD_AUDIO_INIT_DATA;

Structure members

Member Description

EPIn Isochronous endpoint for sending data to the host. If micro-

phone functionality is not desired set this to 0.

EPOut Isochronous endpoint for receiving data from the host. If

speaker functionality is not desired set this to 0.

pBufOut Buffer used with OUT transfers (speaker interface).

pBufIn Buffer used with IN transfers (microphone interface).

InPacketSize Size of a single audio IN packet. Must be calculated as fol-

lows: SampleRate * NumChannels * BitsPerSample/8 / 1000

OutPacketSize Size of a single audio OUT packet. Must be calculated as fol-

lows: SampleRate * NumChannels * BitsPerSample/8 / 1000

pfOnOut Pointer to a function of type USBD_AUDIO_RX_FUNC which

handles incoming audio data. Needs to be set when the

speaker interface is used.

pfOnIn Pointer to a function of type USBD_AUDIO_TX_FUNC which

handles outgoing audio data. Needs to be set when the mi-

crophone interface is used.

pfOnControl Pointer to a function of type USBD_AUDIO_CONTROL_FUNC

which handles audio commands. Always needs to be set.

pControlUserContext Pointer to a user context which is passed to the pfOnCon-

trol function. Optional, can be NULL..

pMicConf

Pointer to a structure of type USBD_AUDIO_MIC_CONF which

contains configuration data for the microphone interface. If

microphone functionality is not desired set this pointer to

NULL.

pSpeakerConf

Pointer to a structure of type USBD_AUDIO_SPEAKER_CONF

which contains configuration data for the speaker interface.

If speaker functionality is not desired set this pointer to

NULL.

443 CHAPTER 15 Target API

Member Description

ReadTimeout Initial timeout for read requests (speaker interface). Can be

changed via USBD_AUDIO_Set_Timeouts .

WriteTimeout Initial timeout for write requests (microphone interface). Can

be changed via USBD_AUDIO_Set_Timeouts .

444 CHAPTER 15 Target API

15.4.2.2 USBD_AUDIO_MIC_CONF

Description

Initialization data for the microphone interface.

Type definition

typedef struct {

U8 Controls;

U8 NrChannels;

U8 SubFrameSize;

U8 BitResolution;

U32 SamFreq;

} USBD_AUDIO_MIC_CONF;

Structure members

Member Description

Controls Reserved.

NrChannels Number of audio channels.

SubFrameSize Size of an audio frame in bytes. Must be able to hold Bi-

tResolution bits.

BitResolution Number of bits inside the audio frame dedicated to audio da-

ta. (Any remaining bits are padding.)

SamFreq Sample frequency.

445 CHAPTER 15 Target API

15.4.2.3 USBD_AUDIO_SPEAKER_CONF

Description

Initialization data for the speaker interface .

Type definition

typedef struct {

U8 Controls;

U8 NrChannels;

U8 SubFrameSize;

U8 BitResolution;

U32 SamFreq;

} USBD_AUDIO_SPEAKER_CONF;

Structure members

Member Description

Controls

A bit set to 1 indicates that the mentioned Control is sup-

ported:

• b0: Mute

• b1: Volume

• b2: Bass

• b3: Mid

• b4: Treble

• b5: Graphic Equalizer

• b6: Automatic Gain

• b7: Delay

NrChannels Number of audio channels.

SubFrameSize Size of an audio frame in bytes. Must be able to hold Bi-

tResolution bits.

BitResolution Number of bits inside the audio frame dedicated to audio da-

ta. (Any remaining bits are padding.)

SamFreq Sample frequency.

446 CHAPTER 15 Target API

15.4.3 Function definitions

15.4.3.1 USBD_AUDIO_TX_FUNC

Description

Definition of the callback which is called when audio data is sent. This callback is called in

the context of USBD_AUDIO_Write_Task()

Type definition

typedef void USBD_AUDIO_TX_FUNC( void * pUserContext,

const U8 * * ppNextBuffer,

U32 * pNextPacketSize);

Parameters

Parameter Description

pUserContext User context which is passed to the callback.

ppNextBuffer

Buffer containing audio samples which should match the

configuration from USBD_AUDIO_MIC_CONF . Initially this

points to the pBufIn from the USBD_AUDIO_INIT_DATA struc-

ture. The user can change this pointer to a different buffer

which will be used in the next transaction or fill the same

buffer with new data.

pNextBufferSize Size of the next buffer.

Example

static void _cbOnIn(void * pUserContext,

const U8 ** ppNextBuffer,

U32 * pNextPacketSize) {

USB_MEMCPY(_pBufMic, _pDataSource, PACKET_SIZE_IN);

*ppNextBuffer = _pBufMic;

*pNextPacketSize = PACKET_SIZE_IN;

}

447 CHAPTER 15 Target API

15.4.3.2 USBD_AUDIO_RX_FUNC

Description

Definition of the callback which is called when audio data is received. This callback is called

in the context of USBD_AUDIO_Read_Task().

Type definition

typedef void USBD_AUDIO_RX_FUNC(void * pUserContext,

int NumBytesReceived,

U8 * * ppNextBuffer,

U32 * pNextBufferSize);

Parameters

Parameter Description

pUserContext User context which is passed to the callback.

NumBytesReceived The number of bytes which have been read in this transac-

tion.

ppNextBuffer

Buffer containing audio samples which should match the

configuration from USBD_AUDIO_SPEAKER_CONF . Initially

this points to the pBufOut from the USBD_AUDIO_INIT_DA-

TA structure. The user can change this pointer to a different

buffer which will be used in the next transaction or leave it

as it is and copy the data from this buffer elsewhere.

pNextBufferSize Size of the next buffer.

448 CHAPTER 15 Target API

Example

static U8 _acBuf1[BUFFER_SIZE];

static U8 _acBuf2[BUFFER_SIZE];

static U8 * _pBuf;

static U8 * _pBufComplete;

static U32 _NumBytesInFullBuffer;

static U32 _NumBytesInBuffer;

// Receive callback function.

static void _cbOnOut(void * pUserContext,

int NumBytesReceived,

U8 ** ppNextBuffer,

U32 * pNextBufferSize) {

char MBEvent;

// Check if the _next_ transfer would still fit into the buffer.

// If not - switch the buffer.

if ((_NumBytesInBuffer + NumBytesReceived + PACKET_SIZE_OUT) > BUFFER_SIZE) {

// Switch buffers.

if (_CurrentBuffer == 1) {

_CurrentBuffer = 2;

_pBuf = _acBuf2;

} else {

_CurrentBuffer = 1;

_pBuf = _acBuf1;

}

_NumBytesInFullBuffer = _NumBytesInBuffer + NumBytesReceived;

_NumBytesInBuffer = 0;

MBEvent = BUFFER_FULL;

// Notify the task that a buffer is full.

if (OS_PutMailCond1(&_MailBox, &MBEvent) != 0) {

printf("Missed packet.");

}

} else {

_pBuf += NumBytesReceived;

_NumBytesInBuffer += NumBytesReceived;

}

*ppNextBuffer = _pBuf;

}

449 CHAPTER 15 Target API

15.4.3.3 USBD_AUDIO_CONTROL_FUNC

Description

Definition of the callback which is called when audio commands are received. This callback

is called in an interrupt context.

Type definition

typedef int USBD_AUDIO_CONTROL_FUNC(void * pUserContext,

U8 Event,

U8 Unit,

U8 ControlSelector,

U8 * pBuffer,

U32 NumBytes);

Parameters

Parameter Description

pUserContext User context which is passed to the callback.

Event Audio event ID.

Unit ID of the feature unit. In case of USB_AUDIO_PLAYBACK_* &

USB_AUDIO_RECORD_*: 0.

ControlSelector ID of the control. In case of USB_AUDIO_PLAYBACK_* &

USB_AUDIO_RECORD_*: 0.

pBuffer

In case of GET events: pointer to a buffer into which the

callback should write the reply. In case of SET events: point-

er to a buffer containing the command value. In case of

USB_AUDIO_PLAYBACK_* & USB_AUDIO_RECORD_*: NULL.

NumBytes In case of GET events: requested size of the reply in bytes.

In case of SET events: number of bytes in pBuffer. In case

of USB_AUDIO_PLAYBACK_* & USB_AUDIO_RECORD_*: 0.

Return value

= 0 Audio command was handled by the callback. The stack will send the reply.

≠ 0 Audio command was not handled by the callback. The stack will STALL the re-

quest.

Additional information

USB_AUDIO_PLAYBACK_* & USB_AUDIO_RECORD_* events are sent upon receiving a Set In-

terface USB request for Alternate Setting 1 for the respective interface (microphone or

speaker). By default an Audio interface is set to Alternative Setting 0 in which it can not

send or receive anything. The host switches the Alternative Setting to 1 when it has to

send data to the device, this can be e.g. triggered by pressing “play” in your music player.

Normally the host should switch the device back to Alternative Interface 0 when it has

stopped sending audio data. This works well on Linux and OS X, but does not work reliably

on Windows. When using Windows as a host it seems to depend on the application whether

these events are generated or not. E.g. with some applications you will receive USB_AU-

DIO_PLAYBACK_START when “play” is pressed, but USB_AUDIO_PLAYBACK_STOP will not be

sent when “pause” or “stop” is pressed. Relying on these events to check when the host has

stopped sending data is not advised, instead set timeouts via USBD_AUDIO_Set_Timeouts

and check for timeouts inside your USBD_AUDIO_RX_FUNC and USBD_AUDIO_TX_FUNC .

450 CHAPTER 15 Target API

Example

// Control callback function.

static int _cbOnControl(void * pUserContext,

U8 Event,

U8 Unit,

U8 ControlSelector,

U8 * pBuffer,

U32 NumBytes) {

int r;

r = 0;

switch (Event) {

case USB_AUDIO_SET_CUR:

switch (ControlSelector) {

case USB_AUDIO_MUTE_CONTROL:

if (*pBuffer == 1) {

_SetMute(1);

} else {

_SetMute(0);

}

break;

default:

r = 1;

break;

}

break;

<...>

<...>

}

return r;

}

Chapter 16

Combining USB components

(Multi-Interface)

In some cases, it is necessary to combine different USB components in one device. This

chapter will describe how to do this and which steps are necessary.

452 CHAPTER 16 Overview

16.1 Overview

The USB specification allows implementation of more than one component (function) in a

single device. This is achieved by combining two or more components. These devices will

be recognized by the USB host as composite device and each component will be recognized

as an independent device.

One device, for example a data logger, can have two components: This device can show

log data files that were stored on a NAND flash through the MSD component. And the con-

figuration of the data logger can be changed by using a BULK component, CDC component

or even HID component.

453 CHAPTER 16 Overview

16.1.1 Single interface device classes

Components can be combined because most USB device classes are based on one interface.

This means that those components describe themselves at the interface descriptor level and

thus makes it easy to combine different or even the same device classes into one device.

Such devices classes are MSD, HID and generic bulk.

16.1.2 Multiple interface device classes

In contrast to the single interfaces classes there are classes with multiple interfaces such

as CDC and AUDIO or VIDEO class. These classes define their class identifier in the device

descriptor. All interface descriptors are recognized as part of the component that is defined

in the device descriptor. This prevents the combination of multiple interface device classes

(for example, CDC) with any other component.

454 CHAPTER 16 Overview

16.1.3 IAD class

To remove this limitation the USB organization defines a descriptor type that allows the

combination of single interface device classes with multiple interface device classes. This

descriptor is called an Interface Association Descriptor (IAD). It decouples the multi-inter-

face class from other interfaces.

Since IAD is an extension to the original USB specification, it is not supported by all hosts,

especially older host software. If IAD is not supported, the device may not be enumerated

correctly.

Supported HOST

At the time of writing, IAD is supported by:

• Windows XP with Service pack 2 and newer

• Linux Kernel 2.6.22 and higher

455 CHAPTER 16 Configuration

16.2 Configuration

In general, no configuration is required. By default, emUSB-Device supports up to four

interfaces. If more interfaces are needed the following macro must be modified:

Type Macro Default Description

Numeric USB_MAX_NUM_IF 4Defines the maximum number of in-

terfaces emUSB-Device shall handle.

Numeric USB_MAX_NUM_IAD 3

Defines the maximum number of

Interface Association Descriptors

emUSB-Device shall handle.

456 CHAPTER 16 How to combine

16.3 How to combine

Combining different single interface emUSB-Device components (Bulk, HID, MSD) is an

easy step, all that needs to be done is calling the appropriate USBD_xxx_Add() function. For

adding the CDC component additional steps need to be taken. For detailed information refer

to emUSB-Device component specific modification on page 460 and check the following

sample.

Requirements

• RTOS, every component requires a separate task.

• Sufficient endpoints for all used device classes. Make sure that your USB device

controller has enough endpoints available to handle all the interfaces that shall be

integrated.

Sample application

The following sample application uses embOS as the RTOS. This listing is taken from

USB_CompositeDevice_CDC_MSD.c.

/*********************************************************************

* SEGGER MICROCONTROLLER GmbH & Co. KG *

* Solutions for real time microcontroller applications *

**********************************************************************

* *

* Internet: www.segger.com Support: support@segger.com *

* *

**********************************************************************

* *

* USB device stack for embedded applications *

* *

**********************************************************************

----------------------------------------------------------------------

File : USB_CompositeDevice_CDC_MSD.c

Purpose : Sample showing a USB device with multiple interfaces (CDC+MSD).

-------- END-OF-HEADER ---------------------------------------------

#include <stdio.h>

#include "USB.h"

#include "USB_CDC.h"

#include "BSP.h"

#include "USB_MSD.h"

#include "FS.h"

#include "RTOS.h"

/*********************************************************************

* Static const data

**********************************************************************

// Information that is used during enumeration.

static const USB_DEVICE_INFO _DeviceInfo = {

0x8765, // VendorId

0x1256, // ProductId

"Vendor", // VendorName

"MSD/CDC Composite device", // ProductName

"1234567890ABCDEF" // SerialNumber

};

// String information used when inquiring the volume 0.

457 CHAPTER 16 How to combine

static const USB_MSD_LUN_INFO _Lun0Info = {

"Vendor", // MSD VendorName

"MSD Volume", // MSD ProductName

"1.00", // MSD ProductVer

"134657890" // MSD SerialNo

};

/*********************************************************************

* Static data

**********************************************************************

// Data for MSD Task

static OS_STACKPTR int _aMSDStack[512]; /* Task stacks */

static OS_TASK _MSDTCB; /* Task-control-blocks */

/*********************************************************************

* Static code

**********************************************************************

/*********************************************************************

* _AddMSD

* Function description

* Add mass storage device to USB stack

static void _AddMSD(void) {

static U8 _abOutBuffer[USB_HS_BULK_MAX_PACKET_SIZE];

USB_MSD_INIT_DATA InitData;

USB_MSD_INST_DATA InstData;

InitData.EPIn = USBD_AddEP(1, USB_TRANSFER_TYPE_BULK,

USB_HS_BULK_MAX_PACKET_SIZE,

NULL, 0);

InitData.EPOut = USBD_AddEP(0, USB_TRANSFER_TYPE_BULK,

USB_HS_BULK_MAX_PACKET_SIZE,

_abOutBuffer, sizeof(_abOutBuffer));

USB_MSD_Add(&InitData);

// Add logical unit 0: RAM drive, using SDRAM

memset(&InstData, 0, sizeof(InstData));

InstData.pAPI = &USB_MSD_StorageByName;

InstData.DriverData.pStart = (void *)"";

InstData.pLunInfo = &_Lun0Info;

USB_MSD_AddUnit(&InstData);

}

/*********************************************************************

* _MSDTask

* Function description

* Add mass storage device to USB stack

static void _MSDTask(void) {

while (1) {

while ((USBD_GetState() & (USB_STAT_CONFIGURED | USB_STAT_SUSPENDED)) !=

USB_STAT_CONFIGURED) {

USB_OS_Delay(50);

}

USB_MSD_Task();

}

/*********************************************************************

* _OnLineCoding

458 CHAPTER 16 How to combine

* Function description

* Called whenever a "SetLineCoding" Packet has been received

* Notes

* (1) Context

* This function is called directly from an ISR in most cases.

static void _OnLineCoding(USB_CDC_LINE_CODING * pLineCoding) {

#if 0

printf("DTERate=%u, CharFormat=%u, ParityType=%u, DataBits=%u\n",

pLineCoding->DTERate,

pLineCoding->CharFormat,

pLineCoding->ParityType,

pLineCoding->DataBits);

#else

BSP_USE_PARA(pLineCoding);

#endif

}

/*********************************************************************

* _AddCDC

* Function description

* Add communication device class to USB stack

static void _AddCDC(void) {

static U8 _abOutBuffer[USB_HS_BULK_MAX_PACKET_SIZE];

USB_CDC_INIT_DATA InitData;

InitData.EPIn = USBD_AddEP(USB_DIR_IN, USB_TRANSFER_TYPE_BULK, 0, NULL, 0);

InitData.EPOut = USBD_AddEP(USB_DIR_OUT, USB_TRANSFER_TYPE_BULK, 0,

_abOutBuffer, sizeof(_abOutBuffer));

InitData.EPInt = USBD_AddEP(USB_DIR_IN, USB_TRANSFER_TYPE_INT, 8, NULL, 0);

USBD_CDC_Add(&InitData);

USBD_CDC_SetOnLineCoding(_OnLineCoding);

}

/*********************************************************************

* Public code

**********************************************************************

/*********************************************************************

* MainTask

* USB handling task.

* Modify to implement the desired protocol

#ifdef __cplusplus

extern "C" { /* Make sure we have C-declarations in C++ programs */

#endif

void MainTask(void);

#ifdef __cplusplus

}

#endif

void MainTask(void) {

USBD_Init();

USBD_EnableIAD();

_AddCDC();

_AddMSD();

USBD_SetDeviceInfo(&_DeviceInfo);

USBD_Start();

BSP_SetLED(0);

OS_CREATETASK(&_MSDTCB, "MSDTask", _MSDTask, 200, _aMSDStack);

while (1) {

char ac[64];

int NumBytesReceived;

459 CHAPTER 16 How to combine

// Wait for configuration

while ((USBD_GetState() & (USB_STAT_CONFIGURED | USB_STAT_SUSPENDED)) !=

USB_STAT_CONFIGURED) {

BSP_ToggleLED(0);

USB_OS_Delay(50);

}

BSP_SetLED(0);

NumBytesReceived = USBD_CDC_Receive(&ac[0], sizeof(ac));

if (NumBytesReceived > 0) {

USBD_CDC_Write(&ac[0], NumBytesReceived);

}

/**************************** end of file ***************************/

460 CHAPTER 16 emUSB-Device component specific modification

16.4 emUSB-Device component specific modification

There are different steps for each emUSB-Device component. The next section shows what

needs to be done on both sides: device and host-side.

16.4.1 BULK component

16.4.1.1 Device side

No modification on device side needs to be made.

16.4.1.2 Host side

No modification on host side needs to be made.

16.4.2 MSD component

16.4.2.1 Device side

No modification on device side needs to be made.

16.4.2.2 Host side

No modification on host side needs to be made.

16.4.3 HID component

16.4.3.1 Device side

No modification on device side needs to be made.

16.4.3.2 Host side

No modification on host side needs to be made.

461 CHAPTER 16 emUSB-Device component specific modification

16.4.4 CDC component

16.4.4.1 Device side

In order to combine the CDC component with other components, the function USBD_En-

ableIAD() needs to be called, otherwise the device will not enumerate correctly. Refer to

section How to combine on page 390 and check the listing of the sample application.

16.4.4.2 Host side

Due to a limitation of the internal CDC serial driver of Windows, a composite device with

CDC component and another device component(s) is only properly recognized by Windows

XP SP3 and above. Linux kernel supports IAD with version 2.6.22. For Windows before

Windows 10 the .inf file needs to be modified. The provided .inf file:

;

; Device installation file for

; USB 2 COM port emulation

;

[Version]

Signature="$Windows NT$"

Class=Ports

ClassGuid={4D36E978-E325-11CE-BFC1-08002BE10318}

Provider=%MFGNAME%

LayoutFile=layout.inf

DriverVer=03/26/2007,6.0.2600.1

CatalogFile=usbser.cat

[Manufacturer]

%MFGNAME%=CDCDevice,NT,NTamd64

[DestinationDirs]

DefaultDestDir = 12

[CDCDevice.NT]

%DESCRIPTION%=DriverInstall,USB\VID_8765&PID_1111&Mi_xx

[CDCDevice.NTamd64]

%DESCRIPTION%=DriverInstall,USB\VID_8765&PID_0234&Mi_xx

%DESCRIPTION%=DriverInstall,USB\VID_8765&PID_1111&Mi_xx

[DriverInstall.NT]

Include=mdmcpq.inf

CopyFiles=FakeModemCopyFileSection

AddReg=DriverInstall.NT.AddReg

[DriverInstall.NT.AddReg]

HKR,,DevLoader,,*ntkern

HKR,,NTMPDriver,,usbser.sys

HKR,,EnumPropPages32,,"MsPorts.dll,SerialPortPropPageProvider"

[DriverInstall.NT.Services]

AddService=usbser, 0x00000002, DriverServiceInst

[DriverServiceInst]

DisplayName=%SERVICE%

ServiceType=1

StartType=3

ErrorControl=1

ServiceBinary=%12%\usbser.sys

[Strings]

MFGNAME = "Manufacturer"

462 CHAPTER 16 emUSB-Device component specific modification

DESCRIPTION = "USB CDC serial port emulation"

SERVICE = "USB CDC serial port emulation"

red - required modifications

Please add the red colored text to your .inf file and change xx with the interface number

of the CDC component.

The interface number is a zero based index and is assigned by the emUSB-Device stack

when calling USBD_CDC_Add() function.

463 CHAPTER 16 MSD and MTP combination feature

16.5 MSD and MTP combination feature

MTP is often preferable because of the advantages it offers over MSD. But MTP is not

natively recognized by macOS. To provide a solution which works on all the major operating

systems SEGGER developed a feature which presents the device as a single interface that

enumerates as MTP or as MSD depending on the host PC’s operating system.

16.5.1 Configuration

The code of the combination feature is contained in the files USB_MSD_MTP.c and

USB_MSD_MTP.h. The MSD and MTP emUSB-Device packages are obviously also necessary

for this to work. The combination feature is disabled by default and can be enabled by setting

the configuration define USB_SUPPORT_MSD_MTP_COMBINATION to 1 inside your USB_Conf.h

file.

This system works similar to MSD or MTP. The device information is added via USBD_MSD_MT-

P_Add, storage information is added for the MSD and MTP module (USBD_MSD_AddUnit

and USBD_MTP_AddStorage). And finally the blocking function USBD_MSD_MTP_Task is called

which handles all the communication as well as switching between MSD and MTP. Source

code excerpt from the MSD+MTP sample USB_MSD_MTP_FS_Start.c:

static void _AddMSDMTP(void) {

USB_MSD_INIT_DATA MSDInitData;

USB_MSD_INST_DATA MSDInstData;

USB_MTP_INIT_DATA MTPInitData;

USB_MTP_INST_DATA MTPInstData;

// Set the endpoints in the MSD init data to the same Endpoints as MTP.

MTPInitData.EPIn = USBD_AddEP(1, USB_TRANSFER_TYPE_BULK,

USB_HS_BULK_MAX_PACKET_SIZE,

NULL, 0);

MSDInitData.EPIn = MTPInitData.EPIn;

MTPInitData.EPOut = USBD_AddEP(0, USB_TRANSFER_TYPE_BULK,

USB_HS_BULK_MAX_PACKET_SIZE,

_acReceiveBuffer,

sizeof(_acReceiveBuffer));

MSDInitData.EPOut = MTPInitData.EPOut;

MTPInitData.EPInt = USBD_AddEP(1, USB_TRANSFER_TYPE_INT,

10, NULL, 0);

MTPInitData.pObjectList = _aObjectList;

MTPInitData.NumBytesObjectList = sizeof(_aObjectList);

MTPInitData.pDataBuffer = _aDataBuffer;

MTPInitData.NumBytesDataBuffer = sizeof(_aDataBuffer);

MTPInitData.pMTPInfo = &_MTPInfo;

USBD_SetDeviceInfo(&_DeviceInfo);

USBD_MSD_MTP_Add(&MSDInitData, &MTPInitData);

// Add logical unit 0 to MSD

memset(&MSDInstData, 0, sizeof(MSDInstData));

MSDInstData.pAPI = &USB_MSD_StorageByName;

MSDInstData.DriverData.pStart = (void *)"";

MSDInstData.DriverData.pSectorBuffer = _aSectorBuffer;

MSDInstData.DriverData.NumBytes4Buffer = sizeof(_aSectorBuffer);

MSDInstData.pLunInfo = &_Lun0Info;

USBD_MSD_AddUnit(&MSDInstData);

// Add a storage driver to MTP component.

MTPInstData.pAPI = &USB_MTP_StorageFS;

MTPInstData.sDescription = "MTP volume";

MTPInstData.sVolumeId = "0123456789";

MTPInstData.DriverData.pRootDir = "";

USBD_MTP_AddStorage(&MTPInstData);

464 CHAPTER 16 MSD and MTP combination feature

}

16.5.2 Limitations

Because of the way libMTP recognizes MTP devices on Linux based systems a device which

uses the MTP/MSD combination feature will be recognized as MSD. Unless the device is

added into the libMTP device list (describing this procedure is beyond the scope of this

documentation).

465 CHAPTER 16 MSD and MTP combination feature

16.5.3 Target API

Function Description

API functions

USBD_MSD_MTP_Add() Adds an MSD/MTP interface to the USB

stack.

USBD_MSD_MTP_GetMode() Returns current function mode.

USBD_MSD_MTP_Task() Main task function of MSD/MTP combi-

nation which switches between MSD and

MTP.

466 CHAPTER 16 MSD and MTP combination feature

16.5.3.1 USBD_MSD_MTP_Add()

Description

Adds an MSD/MTP interface to the USB stack.

Prototype

int USBD_MSD_MTP_Add(const USB_MSD_INIT_DATA * pMSDInitData,

const USB_MTP_INIT_DATA * pMTPInitData);

Parameters

Parameter Description

pMSDInitData Pointer to a USB_MSD_INIT_DATA structure.

pMTPInitData Pointer to a USB_MTP_INIT_DATA structure.

Return value

0 = Successfully added.

Additional information

After the initialization of USB core, this is the first function that needs to be called when

an MSD/MTP interface is used with emUSB-Device. The structures USB_MTP_INIT_DATA and

USB_MSD_INIT_DATA have to be initialized before USBD_MSD_MTP_Add() is called. The bulk

endpoints configured for MTP and MSD must be the same. Refer to USB_MTP_INIT_DATA

and USB_MSD_INIT_DATA for more information.

467 CHAPTER 16 MSD and MTP combination feature

16.5.3.2 USBD_MSD_MTP_GetMode()

Description

Returns current function mode.

Prototype

int USBD_MSD_MTP_GetMode(void);

Return value

USBD_MSD_MTP_MODE_NOT_INITED Not connected or not initialized yet.

USBD_MSD_MTP_MODE_MSD Running as MSD.

USBD_MSD_MTP_MODE_MTP Running as MTP.

Additional information

This function can be used to make sure that the application code does not access the storage

medium when running as MSD.

468 CHAPTER 16 MSD and MTP combination feature

16.5.3.3 USBD_MSD_MTP_Task()

Description

Main task function of MSD/MTP combination which switches between MSD and MTP.

Prototype

void USBD_MSD_MTP_Task(void);

Additional information

The function returns when the USB device is detached or suspended.

Chapter 17

Target OS Interface

This chapter describes the functions of the operating system abstraction layer.

470 CHAPTER 17 General information

17.1 General information

emUSB-Device includes an OS abstraction layer which should make it possible to use an

arbitrary operating system together with emUSB-Device. To adapt emUSB-Device to a new

OS one only has to map the functions listed below in section Interface function list to the

native OS functions.

This chapter describes the advanced OS layer used by the USB stack if the preprocessor

define USBD_OS_LAYER_EX is set to 1 in USB_Conf.h. If not set, the old, deprecated OS

layer interface is used.

SEGGER took great care when designing this abstraction layer, to make it easy to under-

stand and to adapt to different operating systems.

17.1.1 Operating system support supplied with this release

In the current version, abstraction layers for embOS and µC/OS-II are available.

A kernel abstraction layer for using emUSB-Device without any RTOS (superloop) is also

supplied.

Abstraction layers for other operating systems are available upon request.

471 CHAPTER 17 Interface function list

17.2 Interface function list

Name Description

API functions

USB_OS_DeInit() Frees all resources used by the OS layer.

USB_OS_Delay() Delays for a given number of ms.

USB_OS_DecRI() Leave a critical region for the USB stack:

Decrements interrupt disable count and

enable interrupts if counter reaches 0.

USB_OS_GetTickCnt() Returns the current system time in mil-

liseconds or system ticks.

USB_OS_IncDI() Enter a critical region for the USB stack:

Increments interrupt disable count and

disables interrupts.

USB_OS_Init() This function initialize all OS objects that

are necessary.

USB_OS_Panic() Halts emUSB-Device.

USB_OS_Signal() Wakes the task waiting for signal.

USB_OS_Wait() Blocks the task until USB_OS_Signal() is

called for a given transaction.

USB_OS_WaitTimed() Blocks the task until USB_OS_Signal() is

called for a given transaction or a timeout

occurs.

472 CHAPTER 17 Interface function list

17.2.0.1 USB_OS_DeInit()

Description

Frees all resources used by the OS layer.

Prototype

void USB_OS_DeInit(void);

473 CHAPTER 17 Interface function list

17.2.0.2 USB_OS_Delay()

Description

Delays for a given number of ms.

Prototype

void USB_OS_Delay(int ms);

Parameters

Parameter Description

ms Number of ms.

474 CHAPTER 17 Interface function list

17.2.0.3 USB_OS_DecRI()

Description

Leave a critical region for the USB stack: Decrements interrupt disable count and enable

interrupts if counter reaches 0.

Prototype

void USB_OS_DecRI(void);

Additional information

The USB stack will perform nested calls to USB_OS_IncDI() and USB_OS_DecRI(). This

function may be called from a task context or from within an interrupt. If called from an

interrupt, it need not do anything.

An alternate implementation would be to

• enable the USB interrupts,

• unlock the mutex or semaphore locked in USB_OS_IncDI()

if the disable count reaches 0.

This may be more efficient, because interrupts of other peripherals can be serviced while

inside a critical section of the USB stack.

475 CHAPTER 17 Interface function list

17.2.0.4 USB_OS_GetTickCnt()

Description

Returns the current system time in milliseconds or system ticks.

Prototype

U32 USB_OS_GetTickCnt(void);

Return value

Current system time.

476 CHAPTER 17 Interface function list

17.2.0.5 USB_OS_IncDI()

Description

Enter a critical region for the USB stack: Increments interrupt disable count and disables

interrupts.

Prototype

void USB_OS_IncDI(void);

Additional information

The USB stack will perform nested calls to USB_OS_IncDI() and USB_OS_DecRI(). This

function may be called from a task context or from within an interrupt. If called from an

interrupt, it need not do anything.

An alternate implementation would be to

• perform a lock using a mutex or semaphore and

• disable the USB interrupts.

This may be more efficient, because interrupts of other peripherals can be serviced while

inside a critical section of the USB stack.

477 CHAPTER 17 Interface function list

17.2.0.6 USB_OS_Init()

Description

This function initialize all OS objects that are necessary.

Prototype

void USB_OS_Init(void);

478 CHAPTER 17 Interface function list

17.2.0.7 USB_OS_Panic()

Description

Halts emUSB-Device. Called if a fatal error is detected.

Prototype

void USB_OS_Panic(const char * pErrMsg);

Parameters

Parameter Description

pErrMsg Pointer to error message string.

479 CHAPTER 17 Interface function list

17.2.0.8 USB_OS_Signal()

Description

Wakes the task waiting for signal.

Prototype

void USB_OS_Signal(unsigned EPIndex,

unsigned TransactCnt);

Parameters

Parameter Description

EPIndex Endpoint index. Signaling must be independent for all end-

points.

TransactCnt Transaction counter. Specifies which transaction has been

finished.

Additional information

This routine is typically called from within an interrupt service routine.

480 CHAPTER 17 Interface function list

17.2.0.9 USB_OS_Wait()

Description

Blocks the task until USB_OS_Signal() is called for a given transaction.

Prototype

void USB_OS_Wait(unsigned EPIndex,

unsigned TransactCnt);

Parameters

Parameter Description

EPIndex Endpoint index. Signaling must be independent for all end-

points.

TransactCnt Transaction counter. Specifies the transaction to wait for.

Additional information

The function must ignore signaling transactions other than given in TransactCnt. If this

transaction was signaled before this function was called, it must return immediately.

This routine is called from a task.

481 CHAPTER 17 Interface function list

17.2.0.10 USB_OS_WaitTimed()

Description

Blocks the task until USB_OS_Signal() is called for a given transaction or a timeout occurs.

Prototype

int USB_OS_WaitTimed(unsigned EPIndex,

unsigned ms,

unsigned TransactCnt);

Parameters

Parameter Description

EPIndex Endpoint index. Signaling must be independent for all end-

points.

ms Timeout time given in ms.

TransactCnt Transaction counter. Specifies the transaction to wait for.

Return value

0 Task was signaled within the given timeout.

1 Timeout occurred.

Additional information

The function must ignore signaling transactions other than given in TransactCnt. If this

transaction was signaled before this function was called, it must return immediately.

USB_OS_WaitTimed() is called from a task. This function is used by all available timed

routines.

Alternatively this function may take the given timeout in units of system ticks of the under-

lying operating system instead of milliseconds. In this case all API functions that support

a timeout parameter use also system ticks for the timeout.

482 CHAPTER 17 Example

17.3 Example

A configuration to use USB with embOS might look like the sample below. This example is

also supplied in the subdirectory OS\embOS\.

/*********************************************************************

* SEGGER MICROCONTROLLER GmbH & Co. KG *

* Solutions for real time microcontroller applications *

**********************************************************************

* *

* Internet: www.segger.com Support: support@segger.com *

* *

**********************************************************************

* *

* USB device stack for embedded applications *

* *

**********************************************************************

----------------------------------------------------------------------

File : USB_OS_embOS.c

Purpose : Kernel abstraction for embOS

Do not modify to allow easy updates !

-------- END-OF-HEADER ---------------------------------------------

#include "USB_Private.h"

#include "RTOS.h"

/*********************************************************************

* Static data

**********************************************************************

static OS_MAILBOX _aMailBox[USB_NUM_EPS + USB_EXTRA_EVENTS];

static U32 _aMBBuffer[USB_NUM_EPS + USB_EXTRA_EVENTS];

/*********************************************************************

* Public code

**********************************************************************

/*********************************************************************

* USB_OS_Init

* Function description

* This function initialize all OS objects that are necessary.

void USB_OS_Init(void) {

unsigned i;

for (i = 0; i < COUNTOF(_aMailBox); i++) {

OS_CreateMB(_aMailBox + i, sizeof(U32), 1, _aMBBuffer + i);

}

/*********************************************************************

* USB_OS_DeInit

* Function description

* Frees all resources used by the OS layer.

void USB_OS_DeInit(void) {

unsigned i;

for (i = 0; i < COUNTOF(_aMailBox); i++) {

OS_DeleteMB(&_aMailBox[i]);

}

483 CHAPTER 17 Example

/**********************************************************

* USB_OS_Signal

* Function description

* Wakes the task waiting for signal.

void USB_OS_Signal(unsigned EPIndex, unsigned TransactCnt) {

U32 Tmp;

do {

OS_GetMail(&_aMailBox[EPIndex], &Tmp);

} while (Tmp != TransactCnt);

}

/**********************************************************

* USB_OS_Wait

* Function description

* Blocks the task until USB_OS_Signal() is called for a given transaction.

void USB_OS_Wait(unsigned EPIndex) {

U32 Tmp;

do {

OS_GetMail(&_aMailBox[EPIndex], &Tmp);

} while (Tmp != TransactCnt);

}

/**********************************************************

* USB_OS_WaitTimed

* Function description

* Blocks the task until USB_OS_Signal() is called for a given transaction or a

timeout

* occurs.

int USB_OS_WaitTimed(unsigned EPIndex, unsigned ms) {

U32 Tmp;

int r;

do {

r = (int)OS_GetMailTimed(&_aMailBox[EPIndex], &Tmp, ms);

} while (r == 0 && Tmp != TransactCnt);

return r;

}

/**********************************************************

* USB_OS_Delay

* Function description

* Delays for a given number of ms.

void USB_OS_Delay(int ms) {

OS_Delay(ms);

}

/**********************************************************

* USB_OS_DecRI

* Function description

* Leave a critical region for the USB stack: Decrements interrupt disable

count and

* enable interrupts if counter reaches 0.

void USB_OS_DecRI(void) {

OS_DecRI();

}

/**********************************************************

* USB_OS_IncDI

484 CHAPTER 17 Example

* Function description

* Enter a critical reagion for the USB stack: Increments interrupt disable

count and

* disables interrupts.

void USB_OS_IncDI(void) {

OS_IncDI();

}

/**********************************************************

* USB_OS_Panic

* Function description

* Halts emUSB-Device. Called if a fatal error is detected.

void USB_OS_Panic(const char *pErrMsg) {

while (pErrMsg);

}

/**********************************************************

* USB_OS_GetTickCnt

* Function description

* Returns the current system time in milliseconds or system ticks.

U32 USB_OS_GetTickCnt(void) {

return OS_Time;

}

/*************************** End of file ****************************/

Chapter 18

Target USB Driver

This chapter describes emUSB-Device hardware interface functions in detail.

486 CHAPTER 18 General information

18.1 General information

Purpose of the USB hardware interface

emUSB-Device does not contain any hardware dependencies. These are encapsulated

through a hardware abstraction layer, which consists of the interface functions described

in this chapter. All of these functions for a particular USB controller are typically located

in a single file, the USB driver. Drivers for hardware which have already been tested with

emUSB-Device are available.

Range of supported USB hardware

The interface has been designed in such a way that it should be possible to use the most

common USB device controllers. This includes USB 1.1 controllers and USB 2.0 controllers,

both as external chips and as part of microcontrollers.

18.1.1 Available USB drivers

An always up to date list can be found at:

https://www.segger.com/emusb-drivers.html

487 CHAPTER 18 Adding a driver to emUSB-Device

18.2 Adding a driver to emUSB-Device

USBD_Init() initializes the internals of the USB stack and is always the first function which

the USB application has to call. USBD_Init() will then call USBD_X_Config(). This function

should be used to perform the following tasks:

• Perform device specific hardware initialisation if neccessary.

• Add a USB driver to your project.

• Optionally install a HWAttach function.

• Install interrupt management functions.

You have to specify the USB device driver which should be used with emUSB-Device. For

this, USBD_AddDriver() should be called in USBD_X_Config() with the identifier of the

driver which is compatible to your hardware as parameter. Refer to the header file USB.h

for a list of all supported devices and their valid identifiers.

The _HWAttach() function should be used to perform hardware-specific actions which are

not part of the USB controller logic (for example, enabling the peripheral clock for USB port).

This function is called from every device driver, but may not be present if your hardware

does not need to perform such actions. A _HWAttach() function may be registered to the

stack by calling USBD_SetAttachFunc() within USBD_X_Config().

Additionally interrupt management functions must be installed using the function USB-

D_SetISRMgmFunc().

Modify USBD_X_Config(), _EnableISR() and if required, _HWAttach().

18.2.1 USBD_X_Config()

Description

Configure the USB stack.

Prototype

void USBD_X_Config(void)

Additional information

This function is always called from USBD_Init().

Example

/* Example excerpt from USB_Config_SAM7A3.c */

#define PID_USB (27) // USB Identifier

#define _AT91C_PIOA_BASE (0xFFFFF400)

#define _AT91C_PIOB_BASE (0xFFFFF600)

#define _AT91C_PMC_BASE (0xFFFFFC00)

#define _PIO_PER_OFFS (0x00)

#define _PIO_OER_OFFS (0x10)

#define _PIO_CODR_OFFS (0x34) /* Clear output data register */

#define _PMC (*(volatile unsigned int*) _AT91C_PMC_BASE)

#define _USB_ID (_PIOB_ID)

#define _USB_OER

(*(volatile unsigned int*) (_AT91C_PIOB_BASE + _PIO_OER_OFFS))

#define _USB_CODR

(*(volatile unsigned int*) (_AT91C_PIOB_BASE + _PIO_CODR_OFFS))

#define _USB_DP_PUP_BIT (1)

static void _HWAttach(void) {

_PMC = (1 << _USB_ID); /* Enable peripheral clock for USB-Port */

_USB_OER = (1 << _USB_DP_PUP_BIT); /* set USB_DP_PUP to output */

_USB_CODR = (1 << _USB_DP_PUP_BIT); /* set _USB_DP_PUP_BIT to low state */

}

static void _EnableISR(USB_ISR_HANDLER * pfISRHandler) {

488 CHAPTER 18 Adding a driver to emUSB-Device

*(U32*)(0xFFFFF080 + 4 * PID_USB) = (U32)pfISRHandler; // Set interrupt vector

*(U32*)(0xFFFFF128) = (1 << PID_USB);

// Clear pending interrupt

*(U32*)(0xFFFFF120) = (1 << PID_USB); // Enable Interrupt

}

void USBD_X_Config(void) {

USBD_AddDriver(&USB_Driver_AtmelSAM7A3);

USBD_SetAttachFunc(_HWAttach);

USBD_SetISRMgmFuncs(_EnableISR, NULL, NULL);

}

Chapter 19

Support

490 CHAPTER 19 Contacting support

19.1 Contacting support

Before contacting support please make sure that you are using the latest version of the

emUSB-Device package. Also please check the chapter Configuring debugging output on

page 37 and run your application with enabled debug support.

If you are a registered emUSB-Device user and you need to contact the emUSB-Device

support please send the following information via email to support_emusb@segger.com:

• Your emUSB-Device registration number.

• emUSB-Device version.

• A detailed description of the problem

• The configuration files USB_Conf*.*

• Any error messages.

Please also take a few moments to help us to improve our service by providing a short

feedback when your support case has been solved.

Chapter 20

Profiling with SystemView

This chapter describes how to configure and enable profiling of emUSB-Device using Sys-

temView.

492 CHAPTER 20 Profiling overview

20.1 Profiling overview

emUSB-Device is instrumented to generate profiling information of API functions and dri-

ver-level functions.

These profiling information expose the run-time behavior of emUSB-Device in an applica-

tion, recording which API functions have been called, how long the execution took, and

revealing which driver-level functions have been called by API functions or events like in-

terrupts.

The profiling information is recorded using SystemView.

SystemView is a real-time recording and visualization tool for profiling data. It exposes

the true run-time behavior of a system, going far deeper than the insight provided by de-

buggers. This is particularly effective when developing and working with complex systems

comprising an OS with multiple threads and interrupts, and one or more middleware com-

ponents.

SystemView can ensure a system performs as designed, can track down inefficiencies, and

show unintended interactions and resource conflicts.

The recording of profiling information with SystemView is minimally intrusive to the system

and can be done on virtually any system. With SEGGER’s Real Time Technology (RTT) and

a J-Link, SystemView can record data in real-time and analyze the data live, while the

system is running.

The emUSB-Device profiling instrumentation can be easily configured and set up.

493 CHAPTER 20 Additional files for profiling

20.2 Additional files for profiling

Additional files are required on target and PC side for full functionality of SystemView.

20.2.1 Additional files on target side

The SystemView module needs to be added to the application to enable profiling. If

not already part of the project, download the sources from https://www.segger.com/sys-

temview.html and add them to the project.

Also make sure that USB_SYSVIEW.c from the /USB/ directory is included in the project.

20.2.2 Additional files on PC side

For fully functional and readable outputs in the SystemView PC application, a description

file for the corresponding middleware is required. This description file extends the values

sent from the target to fully readable text outputs.

While SystemView already comes with the most recent description files at the time the

SystemView release has been built, these files might not be the latest available. The latest

SystemView description files can be found in the emUSB-Device shipment in the folder

/Shared/SystemView/Description/. You can copy these files over to the Description

folder that comes with the SystemView package.

The version at the end of the SystemView description file does not have to match the exact

version of the middleware it is used with. They are valid from this version onwards until a

description file for a newer version is required.

494 CHAPTER 20 Enable profiling

20.3 Enable profiling

Profiling can be included or excluded at compile-time and enabled at run-time. When pro-

filing is excluded, no additional overhead in performance or memory usage is generated.

Even when profiling is enabled the overhead is minimal, due to the efficient implementation

of SystemView.

To include profiling, define USBD_SUPPORT_PROFILE as 1 in the emUSB-Device configuration

(USB_Conf.h) or in the project preprocessor defines.

Per default profiling is included when the global define SUPPORT_PROFILE is set.

#if defined(SUPPORT_PROFILE) && (SUPPORT_PROFILE)

#ifndef USBD_SUPPORT_PROFILE

#define USBD_SUPPORT_PROFILE 1

#endif

To enable profiling at run-time, USBD_SYSVIEW_Init() needs to be called. Profiling can

be enabled at any time, it is recommended to do this in the user-provided configuration

USBD_X_Config():

/*********************************************************************

* USBD_X_Config

void USBD_X_Config(void) {

...

#if USBD_SUPPORT_PROFILE

USBD_SYSVIEW_Init();

#endif

...

495 CHAPTER 20 Recording and analyzing profiling information

20.4 Recording and analyzing profiling information

When profiling is included and enabled emUSB-Device generates profiling events. On a

system which supports RTT (i.e. ARM Cortex-M and Renesas RX) the data can be read and

analyzed with SystemView and a J-Link. Connect the J-Link to the target system using the

default debug interface and start the SystemView host application. If the system does not

support RTT, SystemView can be configured for single-shot or postmortem mode. Please

refer to the SystemView User Manual for more information.

Chapter 21

Debugging

emUSB-Device comes with various debugging options. These includes optional warning and

log outputs, as well as other run-time options which perform checks at run time as well

as options to drop incoming or outgoing packets to test stability of the implementation on

the target system.

497 CHAPTER 21 Message output

21.1 Message output

The debug builds of emUSB-Device include a fine grained debug system which helps to

analyze the correct implementation of the stack in your application. All modules of the USB

stack can output logging and warning messages via terminal I/O, if the specific message

type identifier is added to the log and/or warn filter mask. This approach provides the

opportunity to get and interpret only the logging and warning messages which are relevant

for the part of the stack that you want to debug.

By default, all of the warning messages and none of the logging messages are activated.

All activated messages are forwarded to the functions USB_X_Log() and USB_X_Warn().

These functions are located in the source file USB_ConfigIO.c and may be customized or

replaced if necessary.

498 CHAPTER 21 API functions

21.2 API functions

Function Description

Filter functions

USBD_AddLogFilter() Adds one or more message types to the

logging filter.

USBD_AddWarnFilter() Adds one or more message types to the

warning filter.

USBD_SetLogFilter() Sets the message type(s) for the logging

filter.

USBD_SetWarnFilter() Sets the message type(s) for the warning

filter.

General debug functions/macros

USB_PANIC Called if the stack encounters a critical sit-

uation.

General helper prototypes

USB_X_Log() This function is called by the stack in de-

bug builds with log output.

USB_X_Warn() This function is called by the stack in de-

bug builds with log output.

499 CHAPTER 21 API functions

21.2.1 USBD_AddLogFilter()

Description

Adds one or more message types to the logging filter.

Prototype

void USBD_AddLogFilter(U32 FilterMask);

Parameters

Parameter Description

FilterMask Specifies which logging messages should be added to the fil-

ter mask. Refer to Message types on page 506 for a list of

valid values for parameter FilterMask.

Additional information

USBD_AddLogFilter() can also be used to remove a filter condition which was set before.

It adds the specified filter to the filter mask via a disjunction.

Example

void Application (void) {

USBD_AddLogFilter(USB_MTYPE_DRIVER); // Activate driver logging messages

USBD_Init();

* Do something

}

500 CHAPTER 21 API functions

21.2.2 USBD_AddWarnFilter()

Description

Adds one or more message types to the warning filter.

Prototype

void USBD_AddWarnFilter(U32 FilterMask);

Parameters

Parameter Description

FilterMask Specifies which warning messages should be added to the

filter mask. Refer to Message types on page 506 for a list of

valid values for parameter FilterMask.

Additional information

USBD_AddWarnFilter() can also be used to remove a filter condition which was set before.

It adds the specified filter to the filter mask via a disjunction.

Example

void Application (void) {

USBD_AddWarnFilter(USB_MTYPE_DRIVER); // Activate driver warning messages

USBD_Init();

* Do something

}

501 CHAPTER 21 API functions

21.2.3 USBD_SetLogFilter()

Description

Sets the message type(s) for the logging filter.

Prototype

void USBD_SetLogFilter(U32 FilterMask);

Parameters

Parameter Description

FilterMask Specifies which logging messages should be set to the filter

mask. Refer to Message types on page 506 for a list of valid

values for parameter FilterMask.

Additional information

This function can be called before USBD_Init(). By default, none of filter conditions are

set. The sample application contain a simple implementation which can be easily modified.

502 CHAPTER 21 API functions

21.2.4 USBD_SetWarnFilter()

Description

Sets the message type(s) for the warning filter.

Prototype

void USBD_SetWarnFilter(U32 FilterMask);

Parameters

Parameter Description

FilterMask Specifies which warning messages should be set to the filter

mask. Refer to Message types on page 506 for a list of valid

values for parameter FilterMask.

Additional information

This function can be called before USBD_Init(). By default, none of filter conditions are

set. The sample application contain a simple implementation which can be easily modified.

503 CHAPTER 21 API functions

21.2.5 USB_PANIC

Description

This macro is called by the stack code when it detects a situation that should not be occurring

and the stack can not continue. The intention for the USB_PANIC() macro is to invoke

whatever debugger may be in use by the programmer. In this way, it acts like an embedded

breakpoint.

Prototype

USB_PANIC (const char * sError);

Additional information

This macro maps to a function in debug builds only. If USB_DEBUG > 0, the macro maps

to the stack internal function void USB_OS_Panic ( const char * sError ). USB_OS_Panic()

disables all interrupts to avoid further task switches, outputs sError via terminal I/O and

loops forever. When using an emulator, you should set a breakpoint at the beginning of

this routine or simply stop the program after a failure. The error message is passed to the

function as parameter. In a release build, this macro is defined empty, so that no additional

code will be included by the linker.

504 CHAPTER 21 API functions

21.2.6 USB_X_Log()

Description

This function is called by the stack in debug builds with log output. In a release build, this

function is not be linked in.

Prototype

void USB_X_Log(const char * s);

Parameters

Parameter Description

sPointer to a string holding the log message.

505 CHAPTER 21 API functions

21.2.7 USB_X_Warn()

Description

This function is called by the stack in debug builds with log output. In a release build, this

function is not be linked in.

Prototype

void USB_X_Warn(const char * s);

Parameters

Parameter Description

sPointer to a string holding the warning message.

506 CHAPTER 21 Message types

21.3 Message types

Description

The same message types are used for log and warning messages. Separate filters can be

used for both log and warnings. For details, refer to USBD_SetLogFilter() and USBD_Set-

WarnFilter() as wells as USBD_AddLogFilter() and USBD_AddWarnFilter() for more in-

formation about using the message types.

Definition

#define USB_MTYPE_INIT (1UL << 0)

#define USB_MTYPE_CORE (1UL << 1)

#define USB_MTYPE_CONFIG (1UL << 2)

#define USB_MTYPE_DRIVER (1UL << 3)

#define USB_MTYPE_ENUMERATION (1UL << 4)

#define USB_MTYPE_CDC (1UL << 7)

#define USB_MTYPE_HID (1UL << 8)

#define USB_MTYPE_MSD (1UL << 9)

#define USB_MTYPE_MSD_CDROM (1UL << 10)

#define USB_MTYPE_MSD_PHY (1UL << 11)

#define USB_MTYPE_MTP (1UL << 12)

#define USB_MTYPE_PRINTER (1UL << 13)

#define USB_MTYPE_RNDIS (1UL << 14)

#define USB_MTYPE_SMART_MSD (1UL << 16)

#define USB_MTYPE_UVC (1UL << 17)

#define USB_MTYPE_ECM (1UL << 18)

#define USB_MTYPE_AUDIO (1UL << 19)

Symbols

Definition Description

USB_MTYPE_INIT Activates output of messages from the initialization of the

stack that should be logged.

USB_MTYPE_CORE Activates output of messages from the core of the stack that

should be logged.

USB_MTYPE_CONFIG Activates output of messages from the configuration of the

stack.

USB_MTYPE_DRIVER Activates output of messages from the driver that should be

logged.

USB_MTYPE_ENUMERATION Activates output of messages from enumeration that should

be logged. Note: Since enumeration is handled in an ISR,

use this with care as the timing will be changed greatly.

USB_MTYPE_CDC Activates output of messages from CDC module that should

be logged when a CDC connection is used.

USB_MTYPE_HID Activates output of messages from HID module that should

be logged when a HID connection is used.

USB_MTYPE_MSD Activates output of messages from MSD module that should

be logged when a MSD connection is used.

USB_MTYPE_MSD_CDROM Activates output of messages from MSD CDROM module that

should be logged.

USB_MTYPE_MSD_PHY Activates output of messages from MSD Physical layer that

should be logged.

USB_MTYPE_MTP Activates output of messages from MTP module that should

be logged when a MTP connection is used.

USB_MTYPE_PRINTER Activates output of messages from Printer module that

should be logged when Printer connection is used.

507 CHAPTER 21 Message types

Definition Description

USB_MTYPE_RNDIS Activates output of messages from RNDIS module that

should be logged when a RNIDS connection is used.

USB_MTYPE_SMART_MSD Activates output of messages from Smart-MSD module that

should be logged when a SmartMSD connection is used.

USB_MTYPE_UVC Activates output of messages from UVC module that should

be logged when a UVC connection is used.

USB_MTYPE_ECM Activates output of messages from ECM module that should

be logged when a ECM connection is used.

USB_MTYPE_AUDIO Activates output of messages from Audio module that should

be logged when an audio connection is used.

Chapter 22

Certification

This chapter describes the process of USB driver certification with Microsoft Windows.

509 CHAPTER 22 What is the Windows Hardware Certification and

why do I need it?

22.1 What is the Windows Hardware Certification and

why do I need it?

The Windows Hardware Certification (formerly known as “Windows Logo Certification”)

process will sign a driver with a Microsoft certificate which signifies that the device is com-

patible and safe to use with Microsoft Windows operating systems.

If the device is using a call which requires .inf files and if the driver is not signed the user

will be confronted with messages saying that the driver is not signed and may not be safe to

use with Microsoft Windows. Depending on which Windows version you are using a different

message will be shown. Users of Windows Server 2008, Windows Vista x64, Windows 7 x64

an newer version of the respective distributions will be warned about the missing signature

and the driver will show up as installed, but the driver will not be loaded. The user can

override this security measure by hitting F8 on Windows start-up and selecting “Disable

Driver Signature Enforcement” or editing the registry.

Microsoft Windows Vista/7:

22.2 Certification offer

Customers can complete the certification by themselves. But SEGGER also offers certifica-

tion for our customers. To certify a device a customer needs a valid Vendor ID, registered

at www.usb.org and a free Product ID. Using the Hardware Certification Kit a certification

package is created. The package is sent to Microsoft for confirmation. After the confirmation

is received from Microsoft the customer receives a .cat file which allows the drivers to be

installed without problems.

22.3 Vendor and Product ID

A detailed description of the Vendor and Product ID can be found in chapter Product /

Vendor IDs on page 32.

The customer can acquire a Vendor ID from the USB Implementers Forum, Inc. (www.us-

b.org). This allows to freely decide which Product ID is used for which product.

510 CHAPTER 22 Certification without SEGGER Microcontroller

22.4 Certification without SEGGER Microcontroller

Certification can be completed by the customer themselves. The certification is a lengthy

and complicated process. For further information, as well as the requirements see:

https://msdn.microsoft.com/en-us/library/windows/hardware/jj124227.aspx

Chapter 23

Performance & resource usage

This chapter covers the performance and resource usage of emUSB-Device. It contains

information about the memory requirements in typical systems which can be used to obtain

sufficient estimates for most target systems.

512 CHAPTER 23 Memory footprint

23.1 Memory footprint

emUSB-Device is designed to fit many kinds of embedded design requirements. Several

features can be excluded from a build to get a minimal system. The code size depends on

the API functions called by the application. The code was compiled for a Cortex-M4 CPU

with size optimization. Note that the values are only valid for an average configuration.

The following table shows the approximate RAM and ROM requirement of emUSB-Device

in bytes:

Component ROM RAM Note

USB core 5800 900

Bulk 2000 100

CDC 1300 100

HID 1600 100

MSD 4800 300

+ size of file system + config-

urable sector buffer of minimum

512 bytes (RAM)

MTP 14600 1600

+ size of file system + config-

urable file data buffer of mini-

mum 512 bytes RAM) + config-

urable object buffer (typically 4

kBytes RAM)

Printer 800 2100

RNDIS 5500 1400 + size of the IP stack

ECM 2800 200 + size of the IP stack

IP-Over-USB 7300 1600 + size of the IP stack

SmartMSD 8300 800 + heap of minimum 1700 bytes

RAM

Driver Atmel SAM3U 2200 600

Driver Atmel SAM3X 2000 600

Driver Atmel SAM3S 2200 100

Driver Atmel SAM7S 2200 100

Driver Atmel SAM9X25 1900 500

Driver Atmel SAMA5D2x 1900 500

Driver Atmel SAMV7 2100 3200

Driver EM EFM32GG990 3100 700

Driver Freescale KHCI 2400 700

Driver Freescale KinetisEHCI 3100 2600

Driver Infineon XMC45xx 2900 400

Driver NXP LPC17xx 1600 100

Driver NXP LPC18xx 3200 4100

Driver NXP LPC23xx 1600 100

Driver NXP LPC43xx 3200 4100

Driver Renesas RZ 3300 7800

Driver Renesas RX 2800 700

Driver Renesas SynergyS1 2800 600

Driver Renesas SynergyFS 2800 700

Driver Renesas SynergyHS 3400 4700

513 CHAPTER 23 Memory footprint

Component ROM RAM Note

Driver ST STM32x32 2000 300

Driver ST STM32F107 2900 400

Driver ST STM32F4xxFS 3000 400

Driver ST STM32F4xxHS 3300 3300

Driver ST STM32F7xxFS 3100 600

Driver ST STM32F7xxHS 3200 4900

Driver ST STM32L4xx 2900 600

Driver ST STR91x 1400 0

Driver TI AM335x 1300 7700

Driver TI OMAP L138 1300 2100

Additionally 64 or 512 bytes of RAM (64 for Full Speed and 512 for High Speed devices)

are necessary for each OUT-endpoint as a data buffer. This buffer is assigned within the

application.

514 CHAPTER 23 Performance

23.2 Performance

The tests were run on a LPC4357 CPU running at 180 MHz using the USB Bulk and the USB

MSD component connected to a Linux host.

The following table shows the transfer speed of emUSB-Device:

Description Speed

USB High-Speed controller (device to host) 44.1 MB/s

USB High-Speed controller (host to device) 41.8 MB/s

USB Full-Speed controller 1200 kB/s

Chapter 24

FAQ

This chapter answers some frequently asked questions.

516 CHAPTER 24

Q: Which CPUs can I use emUSB-Device with?

A: It can be used with any CPU (or MPU) for which a C compiler exists. Of course, it will

work faster on 16/32-bit CPUs than on 8-bit CPUs.

Q: When designing my hardware can I just permanently connect the D+ 1.5 kOhm

pull-up resistor to 3.3V to save a MCU pin?

A: No, the pull-up being connected tells the USB host that the device is ready to

communicate. Permanently connecting the pull-up is dangerous as the host may start

to communicate with the device prematurely, before it has finished with the start-up.

Furthermore, when using USB high-speed the device must disconnect the pull-up from

D+ according to the USB 2.0 specification. Any currently know USB high speed controller

(with internal or external USB Highspeed PHY) have internal logic to enable an internal

pull-up initially. So for those controller an external pull-up is not necessary.

Q: When using MSD can I read/write onto the storage medium when the device

is connected to a USB host?

A: No, when a MSC device is connected to a USB host the host is the sole master of

the storage medium. It can write or read at any point in time. Should the application

try to access the storage medium at the same time as the host the results are

unpredictable. To resolve this issue the device needs to detach the storage medium

from the host, see USBD_MSD_RequestDisconnect(), USBD_MSD_Disconnect() and

USBD_MSD_WaitForDisconnection().

Q: Can I combine different USB components together?

A: Yes. See Combining USB components (Multi-Interface) on page 451.

Q: Do I need a real-time operating system (RTOS) to use the emUSB-Device-MSD?

A: No, if your target application is a pure storage application. You do not need an RTOS if

all you want to do is running emUSB-Device-MSD as the only task on the target device.

If your target application is more than just a storage device and needs to perform

other tasks simultaneously, you need an RTOS which handles the multi-tasking. We

recommend using our embOS Real-time OS, since all example and trial projects are

based on it.

Q: Do I need extra file system code to use the emUSB-Device-MSD?

A: No, if you access the target data only from the host. Yes, if you want to access the target

data from within the target itself. There is no extra file system code needed if you only

want to access the data on the target from the host side. The host OS already provides

several file systems. You have to provide file system program code on the target only

if you want to access the data from within the target application itself.

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