Features * MPEGI/II-Layer 3 Hardwired Decoder * * * * * * * * * * * * * * * * * * * * - Stand-alone MP3 Decoder - 48, 44.1, 32, 24, 22.05, 16 kHz Sampling Frequency - Separated Digital Volume Control on Left and Right Channels (Software Control using 31 Steps) - Bass, Medium, and Treble Control (31 Steps) - Bass Boost Sound Effect - Ancillary Data Extraction - CRC Error and MPEG Frame Synchronization Indicators Programmable Audio Output for Interfacing With Common Audio DAC - PCM Format Compatible - I2S Format Compatible 8-bit MCU C51 Core Based (F MAX = 20 MHz) 2304 bytes of Internal RAM 64K bytes of Code Memory - Flash: AT89C51SND1A, ROM: AT83C51SND1A 4K bytes of Boot Flash Memory (AT89C51SND1A) - ISP: Download from USB or UART to any External Memory Cards USB Rev 1.1 Controller - Full Speed Data Transmission Built-in PLL - MP3 Audio Clocks - USB Clock MultiMediaCardTM Interface Compatibility Atmel DataFlash (R) SPI Interface Compatibility IDE/ATAPI Interface 2 Channels 10-bit ADC, 8 kHz (8 true bit) - Battery Voltage Monitoring - Voice Recording Controlled by Software Up to 44 bits of General-purpose I/Os for: - 4-bit Interrupt Keyboard Port for a 4 x n Matrix - Smartmedia(R) Software Interface Two Standard 16-bit Timers/Counters Hardware Watchdog Timer Standard Full Duplex UART with Baud Rate Generator Two-wire Master and Slave Modes Controller SPI Master and Slave Modes Controller Power Management - Power-on reset - Software Programmable MCU Clock - Idle Mode, Power-down Mode Operating Conditions: - 3V, 10%, 25 mA Typical Operating at 25C - Temperature Range: -40C to +85C Packages - TQFP80, PLCC84 (Development Board) - Dice Single Chip Flash with MP3 Decoder and Man Machine Interface AT8xC51SND1A Design Guide Preliminary Description The AT8xC51SND1A is a fully integrated stand-alone hardwired MPEGI/II-Layer 3 decoder with a C51 microcontroller core handling data flow and MP3-player control. The AT89C51SND1A includes 64K bytes of Flash memory and allows In-System Programming through an embedded 4K bytes of Boot Flash Memory. Rev. 4109C-8051-03/02 1 The AT83C51SND1A includes 64K bytes of ROM memory. The AT8xC51SND1A includes 2304 bytes of RAM memory. The AT8xC51SND1A provides all necessary features for man machine interface like timers, keyboard port, serial or parallel interface (USB, two-wire, SPI, IDE), ADC input, I 2 S output, and all external memory interface (NAND or NOR Flash, SmartMedia, MultiMedia). Typical Applications 2 * MP3-Player * PDA, Camera, Mobile Phone MP3 * Car Audio/Multimedia MP3 * Home Audio/Multimedia MP3 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Block Diagram Figure 1. AT8xC51SND1A Block Diagram INT0# INT1# VDD VSS UVDD UVSS AVDD AVSS AREF AIN1:0 TXD RXD T0 T1 SS# MISO MOSI SCK SCL SDA 1 Interrupt Handler Unit RAM 2304 bytes 10-bit A to D Converter UART & BRG Timers 0/1 Watchdog SPI/DataFlash Controller 2-wire Controller 8-BIT INTERNAL BUS C51 (X2 CORE) MP3 Decoder Unit Clock & PLL Unit FLASH ROM 64K bytes FLASH Boot 4K bytes 1 I2S/PCM Audio Interface USB Controller MMC Interface Keyboard Interface I/O Ports IDE Interface 1 FILT X1 X2 RST ISP# ALE DOUT DCLK DSEL SCLK D+ D- MCLK MDAT MCMD KIN3:0 P0-P5 1 Alternate function of Port 1 2 Alternate function of Port 3 3 Alternate function of Port 4 3 4109C-8051-03/02 Clock Controller The AT8xC51SND1A clock controller is based on an on-chip oscillator feeding an onchip Phase Lock Loop (PLL). All internal clocks to the peripherals and CPU core are generated by this controller. Oscillator The AT8xC51SND1A X1 and X2 pins are the input and the output of a single-stage onchip inverter (see Figure 2), that can be configured with off-chip components such as a Pierce oscillator (see Figure 3). Value of capacitors and crystal characteristics are detailed in the Section "DC Characteristics" of the AT8xC51SND1A datasheet. The oscillator outputs three different clocks: a clock for the PLL, a clock for the CPU core, and a clock for the peripherals symbolized as shown in Figure 2. These clocks are either enabled or not enabled, depending on the power reduction mode as detailed in "Power Management" on page 41. The peripheral clock is used to generate the Timer 0, Timer 1, MMC, ADC, SPI, and Port sampling clocks. Figure 2. Oscillator Block Diagram and Symbol /2 X1 PER CLOCK 0 Peripheral Clock 1 Peripheral Clock Symbol CPU Core Clock X2 CPU CLOCK X2 CKCON.0 IDL CPU Core Clock Symbol PCON.0 PD Oscillator Clock PCON.1 OSC CLOCK Oscillator Clock Symbol Figure 3. Crystal Connection X1 C1 Q C2 VSS X2 Feature Unlike standard C51 products that require 12 oscillator clock periods per machine cycle, the AT8xC51SND1A needs only 6 oscillator clock periods per machine cycle. This feature called the "X2 feature" can be enabled using the X2 bit(1) in CKCON (see Table 1) and allows the AT8xC51SND1A to operate in 6 or 12 oscillator clock periods per machine cycle. As shown in Figure 2, both CPU and peripheral clocks are affected by this feature. Figure 4 shows the X2 mode switching waveforms. After reset the standard mode is activated. In standard mode the CPU and peripheral clock frequency is the oscillator frequency divided by 2 while in X2 mode, it is the oscillator frequency. Note: 4 X2 1. The X2 bit reset value depends on the X2B bit in the Hardware Byte (see Table 6 on page 15). Using the AT89C51SND1A (Flash Version) the system can boot either in standard or X2 mode depending on the X2B value. Using AT83C51SND1A (ROM Version) the system always boots in standard mode. X2B bit can be changed to X2 mode later by software. AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Figure 4. Mode Switching Waveforms X1 X1/2 X2 bit Clock STD Mode Note: X2 Mode STD Mode In order to prevent any incorrect operation while operating in X2 mode, you must be aware that all peripherals using clock frequency as time reference (timers...) will have their time reference divided by two. For example, a free running timer generating an interrupt every 20 ms will then generate an interrupt every 10 ms. PLL PLL Description The AT8xC51SND1A PLL is used to generate internal high frequency clock (the PLL Clock) synchronized with an external low-frequency (the Oscillator Clock). The PLL clock provides the MP3 decoder, the audio interface, and the USB interface clocks. Figure 5 shows the internal structure of the PLL. The PFLD block is the Phase Frequency Comparator and Lock Detector. This block makes the comparison between the reference clock coming from the N divider and the reverse clock coming from the R divider and generates some pulses on the Up or Down signal depending on the edge position of the reverse clock. The PLLEN bit in PLLCON register is used to enable the clock generation. When the PLL is locked, the bit PLOCK in PLLCON register (see Table 2) is set. The CHP block is the Charge Pump that generates the voltage reference for the VCO by injecting or extracting charges from the external filter connected on PFILT pin (see Figure 6). Value of the filter components are detailed in the Section "DC Characteristics" of the AT8xC51SND1A datasheet. The VCO block is the Voltage Controlled Oscillator controlled by the voltage Vref produced by the charge pump. It generates a square wave signal: the PLL clock. Figure 5. PLL Block Diagram and Symbol PFILT PLLCON.1 PLLEN N divider OSC CLOCK N6:0 Up PFLD CHP Vref VCO PLL Clock Down PLOCK PLLCON.0 R divider R9:0 OSCclk x ( R + 1 ) PLLclk = ----------------------------------------------N+1 PLL CLOCK PLL Clock Symbol 5 4109C-8051-03/02 Figure 6. PLL Filter Connection PFILT R C2 C1 VSS PLL Programming VSS The PLL is programmed using the flow shown in Figure 7. As soon as clock generation is enabled, you must wait until the lock indicator is set to ensure the clock output is stable. The PLL clock frequency will depend on MP3 decoder clock and audio interface clock frequencies. Figure 7. PLL Programming Flow PLL Programming Configure Dividers N6:0 = xxxxxxb R9:0 = xxxxxxxxxxb Enable PLL PLLRES = 0 PLLEN = 1 PLL Locked? PLOCK = 1? 6 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Registers Table 1. CKCON Register CKCON (S:8Fh) - Clock Control Register 7 6 5 4 3 2 1 0 - WDX2 - - - T1X2 T0X2 X2 Bit Number 7 Bit Mnemonic Description - 6 WDX2 5-3 - 2 1 0 Reserved The value read from this bit is indeterminate. Do not set this bit. Watchdog Clock Control Bit Set to select the oscillator clock divided by two as watchdog clock input (X2 independent). Clear to select the peripheral clock as watchdog clock input (X2 dependent). Reserved The value read from these bits is indeterminate. Do not set these bits. T1X2 Timer 1 Clock Control Bit Set to select the oscillator clock divided by two as timer 1 clock input (X2 independent). Clear to select the peripheral clock as timer 1 clock input (X2 dependent). T0X2 Timer 0 Clock Control Bit Set to select the oscillator clock divided by two as timer 0 clock input (X2 independent). Clear to select the peripheral clock as timer 0 clock input (X2 dependent). X2 System Clock Control Bit Clear to select 12 clock periods per machine cycle (STD mode, FCPU = FPER = FOSC/2). Set to select 6 clock periods per machine cycle (X2 mode, FCPU = FPER = FOSC). Reset Value = 0000 000Xb 7 4109C-8051-03/02 Table 2. PLLCON Register PLLCON (S:E9h) - PLL Control Register. 7 6 5 4 3 2 1 0 R1 R0 - - PLLRES - PLLEN PLOCK Bit Number Bit Mnemonic Description PLL Least Significant Bits R Divider 2 LSB of the 10-bit R divider. 7-6 R1:0 5-4 - 3 PLLRES 2 - 1 PLLEN PLL Enable Bit Set to enable the PLL. Clear to disable the PLL. 0 PLOCK PLL Lock Indicator Set by hardware when PLL is locked. Clear by hardware when PLL is unlocked. Reserved The value read from these bits is always 0. Do not set these bits. PLL Reset Bit Set this bit to reset the PLL. Clear this bit to free the PLL and allow enabling. Reserved The value read from this bit is always 0. Do not set this bit. Reset Value = 0000 1000b Table 3. PLLNDIV Register PLLNDIV (S:EEh) - PLL N Divider Register. 7 6 5 4 3 2 1 0 - N6 N5 N4 N3 N2 N1 N0 Bit Number Bit Mnemonic Description 7 - 6-0 N6:0 Reserved The value read from this bit is always 0. Do not set this bit. PLL N Divider 7-bit N divider. Reset Value = 0000 0000b 8 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 4. PLLRDIV Register PLLRDIV (S:EFh) - PLL R Divider Register 7 6 5 4 3 2 1 0 R9 R8 R7 R6 R5 R4 R3 R2 Bit Number 7-0 Bit Mnemonic Description R9:2 PLL Most Significant Bits R Divider 8 MSB of the 10-bit R divider. Reset Value = 0000 0000b 9 4109C-8051-03/02 Program/Code Memory The AT89C51SND1A and AT83C51SND1A implement 64K bytes of on-chip program/code memory. Figure 8 shows the split of internal and external program/code memory spaces depending on the product. The AT83C51SND1A product provides the internal program/code memory in ROM memory while the AT89C51SND1A product provides it in Flash memory. These two products do not allow external code memory execution. The Flash memory increases EPROM and ROM functionality by in-circuit electrical erasure and programming. The high voltage needed for programming or erasing Flash cells is generated on-chip using the standard VDD voltage, made possible by the internal charge pump. Thus, the AT89C51SND1A can be programmed using only one voltage and allows in application software programming. Hardware programming mode is also available using common programming tool. The AT89C51SND1A implements an additional 4K bytes of on-chip boot Flash memory provided in Flash memory. This boot memory is delivered programmed with a standard boot loader software allowing In-System Programming (ISP). It also contains some Application Programming Interfaces routines named API routines allowing In Application Programming (IAP) by using user's own boot loader. Figure 8. Program/Code Memory Organization FFFFh FFFFh FFFFh F000h F000h 64K bytes Code ROM 64K bytes Code Flash 0000h 0000h AT83C51SND1A ROM Memory Architecture 4K bytes Boot Flash AT89C51SND1A As shown in Figure 9 the AT83C51SND1A ROM memory is composed of two spaces detailed in the following paragraphs. Figure 9. ROM Memory Architecture FFFFh 64K bytes User ROM Memory 0000h 10 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A User Space This space is composed of a 64K bytes ROM memory programmed during the manufacturing process. It contains you's application code. Flash Memory Architecture As shown in Figure 1 the AT89C51SND1A Flash memory is composed of four spaces detailed in the following paragraphs. Figure 1. Flash Memory Architecture Hardware Security Extra Row FFFFh FFFFh 4K bytes Flash Memory F000h Boot 64K bytes User Flash Memory 0000h User Space This space is composed of a 64K bytes Flash memory organized in 512 pages of 128 bytes. It contains you's application code. This space can be read or written by both software and hardware modes. Boot Space This space is composed of a 4K bytes Flash memory. It contains the boot loader for InSystem Programming and the routines for In Application Programming. This space can only be read or written by hardware mode using a parallel programming tool. Hardware Security Space This space is composed of one byte: the Hardware Security Byte (HSB see Table 6) divided in two separate nibbles. The MSN contains the X2 mode configuration bit and the Boot Loader Jump Bit as detailed in Section and can be written by software while the LSN contains the lock system level to protect the memory content against piracy as detailed in Section and can only be written by hardware. 11 4109C-8051-03/02 Extra Row Space This space is composed of two bytes: Hardware Security System * the Software Boot Vector (SBV see Table 7). This byte is used by the software boot loader to build the boot address. * the Software Security Byte (SSB see Figure ). This byte is used to lock the execution of some boot loader commands. The AT89C51SND1A implements three lock bits LB2:0 in the LSN of HSB (see Table 6) providing three levels of security for user's program as described in Table 5 while the AT83C51SND1A is always set in read disabled mode. Level 0 is the level of an erased part and does not enable any security feature. Level 1 locks the hardware programming of both user and boot memories. Level 2 locks also hardware verifying of both user and boot memories Level 3 locks also the external execution. Table 5. Lock Bits Features Hardware Verifying Hardware Programming Software Programming Enable Enable Enable Enable Enable Enable Enable Disable Enable X Enable Enable Disable Disable Enable X Enable Disable Disable Disable Enable Level LB22 LB1 LB0 0 U U U Enable 1 U U P 2 U P P X 33 Notes: Internal Execution External Execution 1. U means unprogrammed, P means programmed and X means don't care (programmed or unprogrammed). 2. LB2 is not implemented in the T8xC51SND1 products. 3. AT89C51SND1A products are delivered with third level programmed to ensure that the code programmed by software using ISP or user's boot loader being secured from any hardware piracy. Boot Memory Execution As internal C51 code space is limited to 64K bytes, some mechanisms are implemented to allow boot memory to be mapped in the code space for execution at addresses from F000h to FFFFh. The boot memory is enabled by setting the ENBOOT bit in AUXR1 (see Figure 2). The three ways to set this bit are detailed in the following sections. Software Boot Mapping The software way to set ENBOOT consists in writing to AUXR1 from you's software. This enables boot loader or API routines execution. Hardware Condition Boot Mapping The hardware condition is based on the ISP# pin. When driving this pin to low level, the chip reset sets ENBOOT and forces the reset vector to F000h instead of 0000h in order to execute the boot loader software. As shown in Figure 10 the hardware condition always allows in-system recovery when user's memory has been corrupted. Programmed Condition Boot Mapping The programmed condition is based on the Boot Loader Jump Bit (BLJB) in HSB. As shown in Figure 10 when this bit is programmed (by hardware or software programming mode), the chip reset set ENBOOT and forces the reset vector to F000h instead of 0000h, in order to execute the boot loader software. 12 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Figure 10. Hardware Boot Process Algorithm RESET Software Process Hardware Process Hard Cond? ISP# = L? Prog Cond? BLJB = P? Standard Init ENBOOT = 0 PC = 0000h FCON = F0h Prog Cond Init ENBOOT = 1 PC = F000h FCON = F0h User's Application Atmel's Boot Loader Hard Cond Init ENBOOT = 1 PC = F000h FCON = 00h The software process (boot loader) is detailed in the section "In System and In-Application Programming" of the AT8xC51SND1A datasheet. Preventing Flash Corruption See "Reset Recommendation to Prevent Flash Corruption" on page 41 in the section Power Management. 13 4109C-8051-03/02 Registers Figure 2. AUXR1 Register AUXR1 (S:A2h) - Auxiliary Register 1 7 6 5 4 3 2 1 0 - - ENBOOT - GF3 0 - DPS Table 4. Bit Number 7-6 Bit Mnemonic Description - Reserved The value read from these bits are indeterminate. Do not set these bits. Enable Boot Flash Set this bit to map the boot flash in the code space between at addresses F000h to FFFFh. Clear this bit to disable boot flash. 5 ENBOOT 4 - 3 GF3 2 0 Always Zero This bit is stuck to logic 0 to allow INC AUXR1 instruction without affecting GF3 flag. 1 - Reserved for Data Pointer Extension. 0 DPS Reserved The value read from this bit is indeterminate. Do not set this bit. General Flag This bit is a general-purpose user flag. Data Pointer Select Bit Set to select second data pointer: DPTR1. Clear to select first data pointer: DPTR0. Reset Value = XXXX 00X0b 14 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Hardware Bytes Table 6. HSB Byte - Hardware Security Byte 7 6 5 4 3 2 1 0 X2B BLJB - - - LB2 LB1 LB0 Table 5. Bit Number Bit Mnemonic Description X2B1 X2 Bit Program this bit to start in X2 mode. Unprogram (erase) this bit to start in standard mode. 6 BLJB Boot Loader Jump Bit Program this bit to execute the boot loader at address F000h on next reset. Unprogram (erase) this bit to execute user's application at address 0000h on next reset. 5-4 - 7 Reserved The value read from these bits is always unprogrammed. Do not program these bits. Reserved 3 The value read from this bit is always unprogrammed. Do not program this bit. 2-0 LB2:0 Hardware Lock Bits Refer to Table 5 for bits description. Reset Value = XXUU UXXX, UUUU UUUU after an hardware full chip erase. Note: 1. X2B initializes the X2 bit in CKCON during the reset phase. 2. Bits 0 to 3 (MSN) can only be programmed by hardware mode. Table 7. SBV Byte - Software Boot Vector 7 6 5 4 3 2 1 0 ADD15 ADD14 ADD13 ADD12 ADD11 ADD10 ADD9 ADD8 Table 3. Bit Number 7-0 Bit Mnemonic Description ADD15:8 MSB of you's boot loader 16-bit address location Refer to the AT8xC51SND1A datasheet for usage information (boot loader dependent). Reset Value = XXXX XXXX, UUUU UUUU after an hardware full chip erase. Table 8. SSB Byte - Software Security Byte 7 6 5 4 3 2 1 0 SSB7 SSB6 SSB5 SSB4 SSB3 SSB2 SSB1 SSB0 Table 4. Bit Number 7-0 Bit Mnemonic Description SSB7:0 Software Security Byte Data Refer to the AT8xC51SND1A datasheet for usage information (boot loader dependent). 15 4109C-8051-03/02 Reset Value = XXXX XXXX, UUUU UUUU after an hardware full chip erase. 16 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Data Memory The AT8xC51SND1A provides data memory access in two different spaces: 1. The internal space mapped in three separate segments: the lower 128 bytes RAM segment the upper 128 bytes RAM segment the expanded 2048 bytes RAM segment 2. The external space. A fourth internal segment is available but dedicated to Special Function Registers, SFRs, (addresses 80h to FFh) accessible by direct addressing mode. For information on this segment, refer to the Section "Special Function Registers", page 24. Figure 11 shows the internal and external data memory spaces organization. Figure 11. Internal and External Data Memory Organization FFFFh 64K bytes External XRAM 7FFh FFh 2K bytes Internal ERAM EXTRAM = 0 00h FFh Upper 128 bytes Internal RAM indirect addressing 80h 7Fh 00h Special Function Registers direct addressing 80h Lower 128 bytes Internal RAM direct or indirect addressing 0800h EXTRAM = 1 0000h Internal Space Lower 128 Bytes RAM The lower 128 bytes of RAM (see Figure 3) are accessible from address 00h to 7Fh using direct or indirect addressing modes. The lowest 32 bytes are grouped into 4 banks of 8 registers (R0 to R7). Two bits RS0 and RS1 in PSW register (see Table 12) select which bank is in use according to Table 9. This allows more efficient use of code space, since register instructions are shorter than instructions that use direct addressing, and can be used for context switching in interrupt service routines. Table 9. Register Bank Selection RS1 RS0 Description 0 0 Register bank 0 from 00h to 07h 0 1 Register bank 1 from 08h to 0Fh 1 0 Register bank 2 from 10h to 17h 1 1 Register bank 3 from 18h to 1Fh The next 16 bytes above the register banks form a block of bit-addressable memory space. The C51 instruction set includes a wide selection of single-bit instructions, and the 128 bits in this area can be directly addressed by these instructions. The bit addresses in this area are 00h to 7Fh. 17 4109C-8051-03/02 Figure 3. Lower 128 bytes Internal RAM Organization 7Fh 30h 2Fh 20h 18h 10h 08h 00h Bit-Addressable Space (Bit Addresses 0-7Fh) 1Fh 17h 0Fh 4 Banks of 8 Registers R0-R7 07h Upper 128 Bytes RAM The upper 128 bytes of RAM are accessible from address 80h to FFh using only indirect addressing mode. Expanded RAM The on-chip 2Kbytes of expanded RAM (ERAM) are accessible from address 0000h to 07FFh using indirect addressing mode through MOVX instructions. In this address range, EXTRAM bit in AUXR register (see Table 13) is used to select the ERAM (default) or the XRAM. As shown in Figure 11 when EXTRAM = 0, the ERAM is selected and when EXTRAM = 1, the XRAM is selected (see Section ). The ERAM memory can be resized using XRS1:0 bits in AUXR register to dynamically increase external access to the XRAM space. Table 10 details the selected ERAM size and address range. Table 10. ERAM Size Selection XRS1 XRS0 0 Note: 18 ERAM Size Address 0 256 bytes 0 to 00FFh 0 1 512 bytes 0 to 01FFh 1 0 1K bytes 0 to 03FFh 1 1 2K bytes 0 to 07FFh Lower 128 bytes RAM, Upper 128 bytes RAM, and expanded RAM are made of volatile memory cells. This means that the RAM content is indeterminate after power-up and must then be initialized properly. AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A External Space Memory Interface The external memory interface comprises the external bus (port 0 and port 2) as well as the bus control signals (RD#, WR#, and ALE). Figure 4 shows the structure of the external address bus. P0 carries address A7:0 while P2 carries address A15:8. Data D7:0 is multiplexed with A7:0 on P0. Table 11 describes the external memory interface signals. Figure 4. External Data Memory Interface Structure RAM PERIPHERAL AT8xC51SND1A A15:8 P2 A15:8 ALE AD7:0 P0 Latch A7:0 A7:0 D7:0 RD# WR# OE WR Table 11. External Data Memory Interface Signals Page Access Mode Signal Name Type A15:8 O AD7:0 I/O ALE O Address Latch Enable ALE signals indicates that valid address information are available on lines AD7:0. RD# O Read Read signal output to external data memory. P3.7 WR# O Write Write signal output to external memory. P3.6 Description Alternate Function Address Lines Upper address lines for the external bus. P2.7:0 Address/Data Lines Multiplexed lower address lines and data for the external memory. P0.7:0 - The AT8xC51SND1A implements a feature called Page Access that disables the output of DPH on P2 when executing MOVX @DPTR instruction. Page Access is enable by setting the DPHDIS bit in AUXR register. Page Access is useful when application uses both ERAM and 256 bytes of XRAM. In this case, software modifies intensively EXTRAM bit to select access to ERAM or XRAM and must save it if used in interrupt service routine. Page Access allows external access above 00FFh address without generating DPH on P2. Thus ERAM is accessed using MOVX @Ri or MOVX @DPTR with DPTR < 0100h, and XRAM is accessed using MOVX @DPTR with DPTR 0100h while keeping P2 for general I/O usage. 19 4109C-8051-03/02 External Bus Cycles This section describes the bus cycles the AT8xC51SND1A executes to read (see Figure 5), and write data (see Figure 6) in the external data memory. External memory cycle takes 6 CPU clock periods. This is equivalent to 12 oscillator clock period in standard mode or 6 oscillator clock periods in X2 mode. For further information on X2 mode, refer to the Section "X2 Feature", page 4. Slow peripherals can be accessed by stretching the read and write cycles. This is done using the M0 bit in AUXR register. Setting this bit changes the width of the RD# and WR# signals from 3 to 15 CPU clock periods. For simplicity, the accompanying figures depict the bus cycle waveforms in idealized form and do not provide precise timing information. For bus cycle timing parameters refer to the Section "AC Characteristics" of the AT8xC51SND1A datasheet. Figure 5. External Data Read Waveforms CPU Clock ALE RD#(1) P0 P2 Notes: DPL or Ri D7:0 DPH or P2(2),(3) P2 1. RD# signal may be stretched using M0 bit in AUXR register. 2. When executing MOVX @Ri instruction, P2 outputs SFR content. 3. When executing MOVX @DPTR instruction, if DPHDIS is set (Page Access Mode), P2 outputs SFR content instead of DPH. Figure 6. External Data Write Waveforms CPU Clock ALE WR#(1) P0 P2 Notes: 20 DPL or Ri P2 D7:0 DPH or P2(2),(3) 1. WR# signal may be stretched using M0 bit in AUXR register. 2. When executing MOVX @Ri instruction, P2 outputs SFR content. 3. When executing MOVX @DPTR instruction, if DPHDIS is set (Page Access Mode), P2 outputs SFR content instead of DPH. AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Dual Data Pointer Description The AT8xC51SND1A implements a second data pointer for speeding up code execution and reducing code size in case of intensive usage of external memory accesses. DPTR0 and DPTR1 are seen by the CPU as DPTR and are accessed using the SFR addresses 83h and 84h that are the DPH and DPL addresses. The DPS bit in AUXR1 register (see Table 14) is used to select whether DPTR is the data pointer 0 or the data pointer 1 (see Figure 7). Figure 7. Dual Data Pointer Implementation DPL0 0 DPL1 1 DPL DPTR0 DPS DPTR1 DPH0 0 DPH1 1 AUXR1.0 DPTR DPH Application Software can take advantage of the additional data pointers to both increase speed and reduce code size, for example, block operations (copy, compare, search ...) are well served by using one data pointer as a "source" pointer and the other one as a "destination" pointer. Hereafter is an example of block move implementation using the two pointers and coded in assembler. The latest C compiler also takes advantage of this feature by providing enhanced algorithm libraries. The INC instruction is a short (2 bytes) and fast (6 CPU clocks) way to manipulate the DPS bit in the AUXR1 register. However, note that the INC instruction does not directly force the DPS bit to a particular state, but simply toggles it. In simple routines, such as the block move example, only the fact that DPS is toggled in the proper sequence matters, not its actual value. In other words, the block move routine works the same whether DPS is '0' or '1' on entry. ; ; ; ; ASCII block move using dual data pointers Modifies DPTR0, DPTR1, A and PSW Ends when encountering NULL character Note: DPS exits opposite of entry state unless an extra INC AUXR1 is added AUXR1EQU0A2h move:movDPTR,#SOURCE ; address of SOURCE incAUXR1 ; switch data pointers movDPTR,#DEST ; address of DEST mv_loop:incAUXR1; switch data pointers movxA,@DPTR; get a byte from SOURCE incDPTR; increment SOURCE address incAUXR1; switch data pointers movx@DPTR,A; write the byte to DEST incDPTR; increment DEST address jnzmv_loop; check for NULL terminator end_move: 21 4109C-8051-03/02 Registers Table 12. PSW Register PSW (S:8Eh) - Program Status Word Register 7 6 5 4 3 2 1 0 CY AC F0 RS1 RS0 OV F1 P Bit Number Bit Mnemonic Description 7 CY Carry Flag Carry out from bit 1 of ALU operands. 6 AC Auxiliary Carry Flag Carry out from bit 1 of addition operands. 5 F0 User Definable Flag 0. 4-3 RS1:0 2 OV Overflow Flag Overflow set by arithmetic operations. 1 F1 User Definable Flag 1. 0 P Parity Bit Set when ACC contains an odd number of 1's. Cleared when ACC contains an even number of 1's. Register Bank Select Bits Refer to Table 9 for bits description. Reset Value = 0000 0000b 22 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 13. AUXR Register AUXR (S:8Eh) - Auxiliary Control Register 7 6 5 4 3 2 1 0 - EXT16 M0 DPHDIS XRS1 XRS0 EXTRAM AO Bit Number Bit Mnemonic Description Reserved The value read from this bit is indeterminate. Do not set this bit. 7 - 6 EXT16 5 M0 4 DPHDIS DPH Disable Bit Set to disable DPH output on P2 when executing MOVX @DPTR instruction. Clear to enable DPH output on P2 when executing MOVX @DPTR instruction. 3-2 XRS1:0 Expanded RAM Size Bits Refer to Table 10 for ERAM size description. 1 EXTRAM 0 AO External 16-bit Access Enable Bit Set to enable 16-bit access mode during MOVX instructions. Clear to disable 16-bit access mode and enable standard 8-bit access mode during MOVX instructions. External Memory Access Stretch Bit Set to stretch RD# or WR# signals duration to 15 CPU clock periods. Clear not to stretch RD# or WR# signals and set duration to 3 CPU clock periods. External RAM Enable Bit Set to select the external XRAM when executing MOVX @Ri or MOVX @DPTR instructions. Clear to select the internal expanded RAM when executing MOVX @Ri or MOVX @DPTR instructions. ALE Output Enable Bit Set to output the ALE signal only during MOVX instructions. Clear to output the ALE signal at a constant rate of FCPU/3. Reset Value = X000 1101b Table 14. AUXR1 Register AUXR1 (S:A2h) - Auxiliary Control Register 1 7 6 5 4 3 2 1 0 - - - - GF3 0 - DPS Bit Number Bit Mnemonic Description Reserved The value read from these bits is indeterminate. Do not set these bits. 7-4 - 3 GF3 2 0 Always Zero This bit is stuck to logic 0 to allow INC AUXR1 instruction without affecting GF3 flag. 1 - Reserved for Data Pointer Extension. 0 DPS General Purpose Flag 3. Data Pointer Select Bit Set to select second data pointer: DPTR1. Clear to select first data pointer: DPTR0. Reset Value = XXXX 00X0b 23 4109C-8051-03/02 Special Function Registers The Special Function Registers (SFRs) of the AT8xC51SND1A derivatives fall into the categories detailed in Table 15 to Table 31. The relative addresses of these SFRs are provided together with their reset values in Table 32. In this table, the bit-addressable registers are identified by Note 1. Table 15. C51 Core SFRs Mnemonic Add Name ACC E0h Accumulator B F0h B Register PSW D0h Program Status Word SP 81h Stack Pointer DPL 82h Data Pointer Low byte DPH 83h Data Pointer High byte 7 6 5 4 3 2 1 0 CY AC F0 RS1 RS0 OV F1 P 7 6 5 4 3 2 1 0 SMOD1 SMOD0 - - GF1 GF0 PD IDL Table 16. System Management SFRs Mnemonic Add Name PCON 87h Power Control AUXR 8Eh Auxiliary Register 0 - EXT16 M0 DPHDIS XRS1 XRS0 EXTRA M AO AUXR1 A2h Auxiliary Register 1 - - ENBOO T - GF3 0 - DPS NVERS FBh Version Number NV7 NV6 NV5 NV4 NV3 NV2 NV1 NV0 7 6 5 4 3 2 1 0 - - - - - - - X2 R1 R0 - - PLLRES - PLLEN PLOCK Table 17. PLL and System Clock SFRs Mnemonic Add Name CKCON 8Fh Clock Control PLLCON E9h PLL Control PLLNDIV EEh PLL N Divider - N6 N5 N4 N3 N2 N1 N0 PLLRDIV EFh PLL R Divider R9 R8 R7 R6 R5 R4 R3 R2 Table 18. Interrupt SFRs Mnemonic Add Name 7 6 5 4 3 2 1 0 IEN0 A8h Interrupt Enable Control 0 EA EAUD EMP3 ES ET1 EX1 ET0 EX0 IEN1 B1h Interrupt Enable Control 1 - EUSB - EKB EADC ESPI EI2C EMMC IPH0 B7h Interrupt Priority Control High 0 - IPHAUD IPHMP3 IPHS IPHT1 IPHX1 IPHT0 IPHX0 IPL0 B8h Interrupt Priority Control Low 0 - IPLAUD IPLMP3 IPLS IPLT1 IPLX1 IPLT0 IPLX0 IPH1 B3h Interrupt Priority Control High 1 - IPHUSB - IPHKB IPHADC IPHSPI IPHI2C IPHMMC IPL1 B2h Interrupt Priority Control Low 1 - IPLUSB - IPLKB IPLADC IPLSPI IPLI2C IPLMMC 24 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 19. Port SFRs Mnemonic Add Name P0 80h 8-bit Port 0 P1 90h 8-bit Port 1 P2 A0h 8-bit Port 2 P3 B0h 8-bit Port 3 P4 C0h 8-bit Port 4 P5 D8h 4-bit Port 5 7 6 5 4 3 2 1 0 - - - - 7 6 5 4 3 2 1 0 FPL3 FPL2 FPL1 FPL0 FPS FMOD1 FMOD0 FBUSY 7 6 5 4 3 2 1 0 Table 20. Flash Memory SFR Mnemonic FCON Add Name D1h Flash Control Table 21. Timer SFRs Mnemonic Add Name TCON 88h Timer/Counter 0 and 1 Control TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0 TMOD 89h Timer/Counter 0 and 1 Modes GATE1 C/T1# M11 M01 GATE0 C/T0# M10 M00 TL0 8Ah Timer/Counter 0 Low Byte TH0 8Ch Timer/Counter 0 High Byte TL1 8Bh Timer/Counter 1 Low Byte TH1 8Dh Timer/Counter 1 High Byte WDTRST A6h WatchDog Timer Reset WDTPRG A7h WatchDog Timer Program - - - - - WTO2 WTO1 WTO0 7 6 5 4 3 2 1 0 Table 22. MP3 Decoder SFRs Mnemonic Add Name MP3CON AAh MP3 Control MPEN MPBBS T CRCEN MSKAN C MSKRE Q MSKLAY MSKSY N MSKCR C MP3STA C8h MP3 Status MPANC MPREQ ERRLAY ERRSY N ERRCR C MPFS1 MPFS0 MPVER MP3STA1 AFh MP3 Status 1 - - - MPFRE Q MPBRE Q - - - 25 4109C-8051-03/02 Table 22. MP3 Decoder SFRs (Continued) Mnemonic Add Name 7 6 5 4 3 2 1 0 MP3DAT ACh MP3 Data MPD7 MPD6 MPD5 MPD4 MPD3 MPD2 MPD1 MPD0 MP3ANC ADh MP3 Ancillary Data AND7 AND6 AND5 AND4 AND3 AND2 AND1 AND0 MP3VOL 9Eh MP3 Audio Volume Control Left - - - VOL4 VOL3 VOL2 VOL1 VOL0 MP3VOR 9Fh MP3 Audio Volume Control Right - - - VOR4 VOR3 VOR2 VOR1 VOR0 MP3BAS B4h MP3 Audio Bass Control - - - BAS4 BAS3 BAS2 BAS1 BAS0 MP3MED B5h MP3 Audio Medium Control - - - MED4 MED3 MED2 MED1 MED0 MP3TRE B6h MP3 Audio Treble Control - - - TRE4 TRE3 TRE2 TRE1 TRE0 MP3CLK EBh MP3 Clock Divider - - - MPCD4 MPCD3 MPCD2 MPCD1 MPCD0 7 6 5 4 3 2 1 0 Table 23. Audio Interface SFRs Mnemonic Add Name AUDCON0 9Ah Audio Control 0 JUST4 JUST3 JUST2 JUST1 JUST0 POL DSIZ HLR AUDCON1 9Bh Audio Control 1 SRC DRQEN MSREQ MUDRN - DUP1 DUP0 AUDEN AUDSTA 9Ch Audio Status SREQ UDRN AUBUS Y - - - - - AUDDAT 9Dh Audio Data AUD7 AUD6 AUD5 AUD4 AUD3 AUD2 AUD1 AUD0 AUDCLK ECh Audio Clock Divider - - - AUCD4 AUCD3 AUCD2 AUCD1 AUCD0 26 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 24. USB Controller SFRs Mnemonic Add Name 7 6 5 4 3 2 1 0 USBCON BCh USB Global Control USBE SUSPCL K SDRMW UP - UPRSM RMWUP E CONFG FADDEN USBADDR C6h USB Address FEN UADD6 UADD5 UADD4 UADD3 UADD2 UADD1 UADD0 USBINT BDh USB Global Interrupt - - WUPCP U EORINT SOFINT - - SPINT USBIEN BEh USB Global Interrupt Enable - - EWUPC PU EEORIN T ESOFIN T - - ESPINT UEPNUM C7h USB Endpoint Number - - - - - - EPNUM 1 EPNUM 0 UEPCONX D4h USB Endpoint X Control EPEN - - - DTGL EPDIR EPTYPE 1 EPTYPE 0 UEPSTAX CEh USB Endpoint X Status DIR - STALLR Q TXRDY STLCRC RXSETU P RXOUT TXCMP UEPRST D5h USB Endpoint Reset - - - - EP3RST EP2RST EP1RST EP0RST UEPINT F8h USB Endpoint Interrupt - - - - EP3INT EP2INT EP1INT EP0INT UEPIEN C2h USB Endpoint Interrupt Enable - - - - EP3INT E EP2INT E EP1INT E EP0INT E UEPDATX CFh USB Endpoint X Fifo Data FDAT7 FDAT6 FDAT5 FDAT4 FDAT3 FDAT2 FDAT1 FDAT0 UBYCTX E2h USB Endpoint X Byte Counter - BYCT6 BYCT5 BYCT4 BYCT3 BYCT2 BYCT1 BYCT0 UFNUML BAh USB Frame Number Low FNUM7 FNUM6 FNUM5 FNUM4 FNUM3 FNUM2 FNUM1 FNUM0 UFNUMH BBh USB Frame Number High - - CRCOK CRCER R - FNUM10 FNUM9 FNUM8 USBCLK EAh USB Clock Divider - - - - - - USBCD1 USBCD0 7 6 5 4 3 2 1 0 Table 25. MMC Controller SFRs Mnemonic Add Name MMCON0 E4h MMC Control 0 DRPTR DTPTR CRPTR CTPTR MBLOC K DFMT RFMT CRCDIS MMCON1 E5h MMC Control 1 BLEN3 BLEN2 BLEN1 BLEN0 DATDIR DATEN RESPE N CMDEN MMCON2 E6h MMC Control 2 MMCEN DCR CCR - - DATD1 DATD0 FLOWC MMSTA DEh MMC Control and Status - - CBUSY CRC16S DATFS CRC7S RESPFS CFLCK MMINT E7h MMC Interrupt MCBI EORI EOCI EOFI F2FI F1FI F2EI F1EI MMMSK DFh MMC Interrupt Mask MCBM EORM EOCM EOFM F2FM F1FM F2EM F1EM MMCMD DDh MMC Command MC7 MC6 MC5 MC4 MC3 MC2 MC1 MC0 MMDAT DCh MMC Data MD7 MD6 MD5 MD4 MD3 MD2 MD1 MD0 MMCLK EDh MMC Clock Divider MMCD7 MMCD6 MMCD5 MMCD4 MMCD3 MMCD2 MMCD1 MMCD0 27 4109C-8051-03/02 Table 26. IDE Interface SFR Mnemonic DAT16H Add F9h Name High Order Data Byte 7 6 5 4 3 2 1 0 D15 D14 D13 D12 D11 D10 D9 D8 7 6 5 4 3 2 1 0 FE/SM0 SM1 SM2 REN TB8 RB8 TI RI BRR TBCK RBCK SPD SRC Table 27. Serial I/O Port SFRs Mnemonic Add Name SCON 98h Serial Control SBUF 99h Serial Data Buffer SADEN B9h Slave Address Mask SADDR A9h Slave Address BDRCON 92h Baud Rate Control BRL 91h Baud Rate Reload Table 28. SPI Controller SFRs Mnemonic Add Name 7 6 5 4 3 2 1 0 SPCON C3h SPI Control SPR2 SPEN SSDIS MSTR CPOL CPHA SPR1 SPR0 SPSTA C4h SPI Status SPIF WCOL - MODF - - - - SPDAT C5h SPI Data SPD7 SPD6 SPD5 SPD4 SPD3 SPD2 SPD1 SPD0 7 6 5 4 3 2 1 0 Table 29. Two-wire Controller SFRs Mnemonic Add Name SSCON 93h Synchronous Serial control SSCR2 SSPE SSSTA SSSTO SSI SSAA SSCR1 SSCR0 SSSTA 94h Synchronous Serial Status SSC4 SSC3 SSC2 SSC1 SSC0 0 0 0 SSDAT 95h Synchronous Serial Data SSD7 SSD6 SSD5 SSD4 SSD3 SSD2 SSD1 SSD0 SSADR 96h Synchronous Serial Address SSA7 SSA6 SSA5 SSA4 SSA3 SSA2 SSA1 SSGC 7 6 5 4 3 2 1 0 Table 30. Keyboard Interface SFRs Mnemonic Add Name KBCON A3h Keyboard Control KINL3 KINL2 KINL1 KINL0 KINM3 KINM2 KINM1 KINM0 KBSTA A4h Keyboard Status KPDE - - - KINF3 KINF2 KINF1 KINF0 28 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 31. A/D Controller SFRs Mnemonic Add Name 7 6 5 4 3 2 1 0 ADCON F3h ADC Control - ADIDL ADEN ADEOC ADSST - - ADCS ADCLK F2h ADC Clock Divider - - - ADCD4 ADCD3 ADCD2 ADCD1 ADCD0 ADDL F4h ADC Data Low Byte - - - - - - ADAT1 ADAT0 ADDH F5h ADC Data High Byte ADAT9 ADAT8 ADAT7 ADAT6 ADAT5 ADAT4 ADAT3 ADAT2 29 4109C-8051-03/02 Table 32. SFR Addresses and Reset Values 0/8 1/9 F8h UEPINT 0000 0000 DAT16H XXXX XXXX F0h B(1) 0000 0000 PLLCON 0000 1000 E8h ACC(1) E0h P5(1) XXXX 1111 D0h PSW1 0000 0000 C8h MP3STA(1) 0000 0001 C0h P4(1) 1111 1111 B8h IPL0(1) X000 0000 B0h 3/B 4/C 5/D 6/E FFh ADCLK 0000 0000 ADCON 0000 0000 ADDL 0000 0000 ADDH 0000 0000 USBCLK 0000 0000 MP3CLK 0000 0000 AUDCLK 0000 0000 MMCLK 0000 0000 PLLNDIV 0000 0000 PLLRDIV 0000 0000 EFh MMCON0 0000 0000 MMCON1 0000 0000 MMCON2 0000 0000 MMINT 0000 0011 E7h MMDAT 1111 1111 MMCMD 1111 1111 MMSTA 0000 0000 MMMSK 1111 1111 DFh UEPCONX 0000 0000 UEPRST 0000 0000 FCON (3) 1111 0000(4) F7h D7h UEPSTAX 0000 0000 UEPDATX 0000 0000 CFh UEPNUM 0000 0000 C7h UEPIEN 0000 0000 SPCON 0001 0100 SPSTA 0000 0000 SPDAT XXXX XXXX USBADDR 1000 0000 SADEN 0000 0000 UFNUML 0000 0000 UFNUMH 0000 0000 USBCON 0000 0000 USBINT 0000 0000 USBIEN 0001 0000 P3(1) 1111 1111 IEN1 0000 0000 IPL1 0000 0000 IPH1 0000 0000 MP3BAS 0000 0000 MP3MED 0000 0000 MP3TRE 0000 0000 A8h IEN0(1) 0000 0000 SADDR 0000 0000 MP3CON 0011 1111 MP3DAT 0000 0000 MP3ANC 0000 0000 A0h P2(1) 1111 1111 98h SCON 0000 0000 90h 88h 80h 7/F NVERS(2) 1000 0010 UBYCTLX 0000 0000 0000 0000 D8h 2/A IPH0 X000 0000 B7h MP3STA1 0100 0001 AFh WDTRST XXX XXXX WDTPRG XXXX X000 A7h MP3VOR 0000 0000 9Fh AUXR1 XXXX 00X0 KBCON 0000 1111 KBSTA 0000 0000 SBUF XXXX XXXX AUDCON0 0000 1000 AUDCON1 1011 0010 AUDSTA 1100 0000 AUDDAT 1111 1111 MP3VOL 0000 0000 P1(1) 1111 1111 BRL 0000 0000 BDRCON XXX0 0000 SSCON 0000 0000 SSSTA 1111 1000 SSDAT 1111 1111 SSADR 1111 1110 TCON(1) 0000 0000 TMOD 0000 0000 TL0 0000 0000 TL1 0000 0000 TH0 0000 0000 TH1 0000 0000 AUXR X000 1101 P0(1) 1111 1111 SP 0000 0111 DPL 0000 0000 DPH 0000 0000 0/8 1/9 2/A 3/B 4/C 5/D BFh 6/E 97h CKCON 0000 000X(5) 8Fh PCON XXXX 0000 87h 7/F Reserved Notes: 30 1. 2. 3. 4. 5. SFR registers with least significant nibble address equal to 0 or 8 are bit-addressable. NVERS reset value depends on the silicon version. FCON register is only available in AT89C51SND1A product. FCON reset value is 00h in case of reset with hardware condition. CKCON reset value depends on the X2B bit (programmed or unprogrammed) in the Hardware Byte. AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Interrupt System The AT8xC51SND1A, like other control-oriented computer architectures, employs a program interrupt method. This operation branches to a subroutine and performs some service in response to the interrupt. When the subroutine completes, execution resumes at the point where the interrupt occurred. Interrupts may occur as a result of internal AT8xC51SND1A activity (e.g., timer overflow) or at the initiation of electrical signals external to the microcontroller (e.g., keyboard). In all cases, interrupt operation is programmed by the system designer, who determines priority of interrupt service relative to normal code execution and other interrupt service routines. All of the interrupt sources are enabled or disabled by the system designer and may be manipulated dynamically. A typical interrupt event chain occurs as follows: * An internal or external device initiates an interrupt-request signal. The AT8xC51SND1A, latches this event into a flag buffer. * The priority of the flag is compared to the priority of other interrupts by the interrupt handler. A high priority causes the handler to set an interrupt flag. * This signals the instruction execution unit to execute a context switch. This context switch breaks the current flow of instruction sequences. The execution unit completes the current instruction prior to a save of the program counter (PC) and reloads the PC with the start address of a software service routine. * The software service routine executes assigned tasks and as a final activity performs a RETI (return from interrupt) instruction. This instruction signals completion of the interrupt, resets the interrupt-in-progress priority and reloads the program counter. Program operation then continues from the original point of interruption. Table 33. Interrupt System Signals Signal Name Type INT0# I External Interrupt 0 See Section "External Interrupts", page 34. P3.2 INT1# I External Interrupt 1 See Section "External Interrupts", page 34. P3.3 KIN3:0 I Keyboard Interrupt Inputs See Section "Keyboard Interface", page 157. Description Alternate Function P1.3:0 Six interrupt registers are used to control the interrupt system. Two 8-bit registers are used to enable separately the interrupt sources: IEN0 and IEN1 registers (see Table 36 and Table 37). Four 8-bit registers are used to establish the priority level of the thirteen sources: IPH0, IPL0, IPH1 and IPL1 registers (see Table 38 to Table 41). Interrupt System Priorities Each of the eleven interrupt sources on the AT8xC51SND1A can be individually programmed to one of four priority levels. This is accomplished by one bit in the Interrupt Priority High registers (IPH0 and IPH1) and one bit in the Interrupt Priority Low registers (IPL0 and IPL1). This provides each interrupt source four possible priority levels according to Table 34. 31 4109C-8051-03/02 Table 34. Priority Levels IPHxx IPLxx Priority Level 0 0 0 Lowest 0 1 1 1 0 2 1 1 3 Highest A low-priority interrupt is always interrupted by a higher priority interrupt but not by another interrupt of lower or equal priority. Higher priority interrupts are serviced before lower priority interrupts. The response to simultaneous occurrence of equal priority interrupts is determined by an internal hardware polling sequence detailed in Table 35. Thus within each priority level there is a second priority structure determined by the polling sequence. The interrupt control system is shown in Figure 12. Table 35. Priority Within Same Level Interrupt Name Priority Number INT0# 1 (Highest Priority) C:0003h H if edge, S if level Timer 0 2 C:000Bh H INT1# 3 C:0013h H if edge, S if level Timer 1 4 C:001Bh H Serial Port 5 C:0023h S MP3 Decoder 6 C:002Bh S Audio Interface 7 C:0033h S MMC Interface 8 C:003Bh S two-wire Controller 9 C:0043h S SPI Controller 10 C:004Bh S A to D Converter 11 C:0053h S Keyboard 12 C:005Bh S Reserved 13 C:0063h - USB 14 C:006Bh S 15 (Lowest Priority) C:0073h - Reserved 32 Interrupt request flag cleared by hardware (H) or by software (S) Interrupt Address Vectors AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Figure 12. Interrupt Control System INT0# 00 01 10 11 External Interrupt 0 Highest Priority Interrupts EX0 00 01 10 11 IEN0.0 Timer 0 ET0 00 01 10 11 IEN0.1 INT1# External Interrupt 1 EX1 00 01 10 11 IEN0.2 Timer 1 ET1 TXD RXD 00 01 10 11 IEN0.3 Serial Port ES 00 01 10 11 IEN0.4 MP3 Decoder EMP3 00 01 10 11 IEN0.5 Audio Interface EAUD MCLK MDAT MCMD 00 01 10 11 IEN0.6 MMC Controller EMMC SCL SDA 00 01 10 11 IEN1.0 two-wire Controller EI2C SCK SI SO 00 01 10 11 IEN1.1 SPI Controller ESPI 00 01 10 11 IEN1.2 AIN1:0 A to D Converter EADC 00 01 10 11 IEN1.3 KIN3:0 Keyboard EKB D+ D- 00 01 10 11 IEN1.4 USB Controller EUSB EA IEN1.6 IEN0.7 Interrupt Enable IPH/L Priority Enable Lowest Priority Interrupts 33 4109C-8051-03/02 External Interrupts INT1:0# Inputs External interrupts INT0# and INT1# (INTn#, n = 0 or 1) pins may each be programmed to be level-triggered or edge-triggered, dependent upon bits IT0 and IT1 (ITn, n = 0 or 1) in TCON register as shown in Figure 8. If ITn = 0, INTn# is triggered by a low level at the pin. If ITn = 1, INTn# is negative-edge triggered. External interrupts are enabled with bits EX0 and EX1 (EXn, n = 0 or 1) in IEN0. Events on INTn# set the interrupt request flag IEn in TCON register. If the interrupt is edge-triggered, the request flag is cleared by hardware when vectoring to the interrupt service routine. If the interrupt is level-triggered, the interrupt service routine must clear the request flag and the interrupt must be deasserted before the end of the interrupt service routine. INT0# and INT1# inputs provide both the capability to exit from Power-down mode on low level signals as detailed in Section "Exiting Power-down Mode", page 43. Figure 8. INT1:0# Input Circuitry INT0/1# INT0/1# Interrupt Request 0 IE0/1 1 TCON.1/3 EX0/1 IEN0.0/2 IT0/1 TCON.0/2 KIN3:0 Inputs External interrupts KIN0 to KIN3 provide the capability to connect a matrix keyboard. For detailed information on these inputs, refer to Section "Keyboard Interface", page 157. Input Sampling External interrupt pins (INT1:0# and KIN3:0) are sampled once per peripheral cycle (6 peripheral clock periods) (see Figure 9). A level-triggered interrupt pin held low or high for more than 6 peripheral clock periods (12 oscillator in standard mode or 6 oscillator clock periods in X2 mode) guarantees detection. Edge-triggered external interrupts must hold the request pin low for at least 6 peripheral clock periods. Figure 9. Minimum Pulse Timings Level-Triggered Interrupt > 1 peripheral cycle 1 cycle Edge-Triggered Interrupt > 1 peripheral cycle 1 cycle 34 1 cycle AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Registers Table 36. IEN0 Register IEN0 (S:A8h) - Interrupt Enable Register 0 7 6 5 4 3 2 1 0 EA EAUD EMP3 ES ET1 EX1 ET0 EX0 Bit Number 7 Bit Mnemonic Description EA Enable All Interrupt Bit Set to enable all interrupts. Clear to disable all interrupts. If EA = 1, each interrupt source is individually enabled or disabled by setting or clearing its interrupt enable bit. 6 EAUD Audio Interface Interrupt Enable Bit Set to enable audio interface interrupt. Clear to disable audio interface interrupt. 5 EMP3 MP3 Decoder Interrupt Enable Bit Set to enable MP3 decoder interrupt. Clear to disable MP3 decoder interrupt. 4 ES Serial Port Interrupt Enable Bit Set to enable serial port interrupt. Clear to disable serial port interrupt. 3 ET1 Timer 1 Overflow Interrupt Enable Bit Set to enable timer 1 overflow interrupt. Clear to disable timer 1 overflow interrupt. 2 EX1 External Interrupt 1 Enable bit Set to enable external interrupt 1. Clear to disable external interrupt 1. 1 ET0 Timer 0 Overflow Interrupt Enable Bit Set to enable timer 0 overflow interrupt. Clear to disable timer 0 overflow interrupt. 0 EX0 External Interrupt 0 Enable Bit Set to enable external interrupt 0. Clear to disable external interrupt 0. Reset Value = 0000 0000b 35 4109C-8051-03/02 Table 37. IEN1 Register IEN1 (S:B1h) - Interrupt Enable Register 1 7 6 5 4 3 2 1 0 - EUSB - EKB EADC ESPI EI2C EMMC Bit Number Bit Mnemonic Description Reserved The value read from this bit is always 0. Do not set this bit. 7 - 6 EUSB 5 - 4 EKB 3 EADC A to D Converter Interrupt Enable Bit Set to enable ADC interrupt. Clear to disable ADC interrupt. 2 ESPI SPI Controller Interrupt Enable Bit Set to enable SPI interrupt. Clear to disable SPI interrupt. 1 EI2C Two-wire Controller Interrupt Enable Bit Set to enable two-wire interrupt. Clear to disable two-wire interrupt. 0 EMMC USB Interface Interrupt Enable Bit Set this bit to enable USB interrupts. Clear this bit to disable USB interrupts. Reserved The value read from this bit is always 0. Do not set this bit. Keyboard Interface Interrupt Enable Bit Set to enable Keyboard interrupt. Clear to disable Keyboard interrupt. MMC Interface Interrupt Enable Bit Set to enable MMC interrupt. Clear to disable MMC interrupt. Reset Value = 0000 0000b 36 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 38. IPH0 Register IPH0 (S:B7h) - Interrupt Priority High Register 0 7 6 5 4 3 2 1 0 - IPHAUD IPHMP3 IPHS IPHT1 IPHX1 IPHT0 IPHX0 Bit Number Bit Mnemonic Description Reserved The value read from this bit is indeterminate. Do not set this bit. 7 - 6 IPHAUD Audio Interface Interrupt Priority Level MSB Refer to Table 34 for priority level description. 5 IPHMP3 MP3 Decoder Interrupt Priority Level MSB Refer to Table 34 for priority level description. 4 IPHS Serial Port Interrupt Priority Level MSB Refer to Table 34 for priority level description. 3 IPHT1 Timer 1 Interrupt Priority Level MSB Refer to Table 34 for priority level description. 2 IPHX1 External Interrupt 1 Priority Level MSB Refer to Table 34 for priority level description. 1 IPHT0 Timer 0 Interrupt Priority Level MSB Refer to Table 34 for priority level description. 0 IPHX0 External Interrupt 0 Priority Level MSB Refer to Table 34 for priority level description. Reset Value = X000 0000b 37 4109C-8051-03/02 Table 39. IPH1 Register IPH1 (S:B3h) - Interrupt Priority High Register 1 7 6 5 4 3 2 1 0 - IPHUSB - IPHKB IPHADC IPHSPI IPHI2C IPHMMC Bit Number Bit Mnemonic Description Reserved The value read from this bit is always 0. Do not set this bit. 7 - 6 IPHUSB 5 - 4 IPHKB 3 IPHADC A to D Converter Interrupt Priority Level MSB Refer to Table 34 for priority level description. 2 IPHSPI SPI Interrupt Priority Level MSB Refer to Table 34 for priority level description. 1 IPHI2C Two-wire Controller Interrupt Priority Level MSB Refer to Table 34 for priority level description. 0 IPHMMC USB Interrupt Priority Level MSB Refer to Table 34 for priority level description. Reserved The value read from this bit is always 0. Do not set this bit. Keyboard Interrupt Priority Level MSB Refer to Table 34 for priority level description. MMC Interrupt Priority Level MSB Refer to Table 34 for priority level description. Reset Value = 0000 0000b 38 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 40. IPL0 Register IPL0 (S:B8h) - Interrupt Priority Low Register 0 7 6 5 4 3 2 1 0 - IPLAUD IPLMP3 IPLS IPLT1 IPLX1 IPLT0 IPLX0 Bit Number Bit Mnemonic Description Reserved The value read from this bit is indeterminate. Do not set this bit. 7 - 6 IPLAUD Audio Interface Interrupt Priority Level LSB Refer to Table 34 for priority level description. 5 IPLMP3 MP3 Decoder Interrupt Priority Level LSB Refer to Table 34 for priority level description. 4 IPLS Serial Port Interrupt Priority Level LSB Refer to Table 34 for priority level description. 3 IPLT1 Timer 1 Interrupt Priority Level LSB Refer to Table 34 for priority level description. 2 IPLX1 External Interrupt 1 Priority Level LSB Refer to Table 34 for priority level description. 1 IPLT0 Timer 0 Interrupt Priority Level LSB Refer to Table 34 for priority level description. 0 IPLX0 External Interrupt 0 Priority Level LSB Refer to Table 34 for priority level description. Reset Value = X000 0000b 39 4109C-8051-03/02 Table 41. IPL1 Register IPL1 (S:B2h) - Interrupt Priority Low Register 1 7 6 5 4 3 2 1 0 - IPLUSB - IPLKB IPLADC IPLSPI IPLI2C IPLMMC Bit Number Bit Mnemonic Description Reserved The value read from this bit is always 0. Do not set this bit. 7 - 6 IPLUSB 5 - 4 IPLKB 3 IPLADC A to D Converter Interrupt Priority Level LSB Refer to Table 34 for priority level description. 2 IPLSPI SPI Interrupt Priority Level LSB Refer to Table 34 for priority level description. 1 IPLI2C Two-wire Controller Interrupt Priority Level LSB Refer to Table 31 for priority level description. 0 IPLMMC USB Interrupt Priority Level LSB Refer to Table 34 for priority level description. Reserved The value read from this bit is always 0. Do not set this bit. Keyboard Interrupt Priority Level LSB Refer to Table 34 for priority level description. MMC Interrupt Priority Level LSB Refer to Table 34 for priority level description. Reset Value = 0000 0000b 40 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Power Management Two power reduction modes are implemented in the AT8xC51SND1A: the Idle mode and the Power-down mode. These modes are detailed in the following sections. In addition to these power reduction modes, the clocks of the core and peripherals can be dynamically divided by 2 using the X2 mode detailed in Section "X2 Feature", page 4. Reset A reset is required after applying power at turn-on. To achieve a valid reset, the reset signal must be maintained for at least 2 machine cycles (24 oscillator clock periods) while the oscillator is running. A device reset initializes the AT8xC51SND1A and vectors the CPU to address 0000h. RST input has a pull-down resistor allowing power-on reset by simply connecting an external capacitor to VDD as shown in Figure 10. Resistor value and input characteristics are discussed in the Section "DC Characteristics" of the AT8xC51SND1A datasheet. The status of the Port pins during reset is detailed in Table 42. Figure 10. Reset Circuitry and Power-On Reset VDD To CPU core and peripherals + R RST RST RST VSS a. RST input circuitry b. Power-on Reset Table 42. Pin Conditions in Special Operating Modes Mode Port 0 Port 1 Port 2 Port 3 Port 4 Port 5 MMC Audio Floating High High High High High Floating 1 Idle Data Data Data Data Data Data Data Data Powerdown Data Data Data Data Data Data Data Data Reset Note: Reset Recommendation to Prevent Flash Corruption 1. Refer to Section "Audio Output Interface", page 67. A bad reset sequence will lead to bad microcontroller initialization and system registers like SFR's, Program Counter, etc. will not be correctly initialized. A bad initialization may lead to unpredictable behaviour of the C51 microcontroller. An example of this situation may occur in an instance where the bit ENBOOT in AUXR1 register is initialized from the hardware bit BLJB upon reset. Since this bit allows mapping of the bootloader in the code area, a reset failure can be critical. If one wants the ENBOOT cleared inorder to unmap the boot from the code area (yet due to a bad reset) the bit ENBOOT in SFR's may be set. If the value of Program Counter is accidently in the range of the boot memory addresses then a flash access (write or erase) may corrupt the Flash on-chip memory . It is recommended to use an external reset circuitry featuring power supply monitoring to prevent system malfunction during periods of insufficient power supply voltage(power supply failure, power supply switched off). 41 4109C-8051-03/02 Idle Mode Idle mode is a power reduction mode that reduces the power consumption. In this mode, program execution halts. Idle mode freezes the clock to the CPU at known states while the peripherals continue to be clocked (refer to Section "Oscillator", page 4). The CPU status before entering Idle mode is preserved, i.e., the program counter and program status word register retain their data for the duration of Idle mode. The contents of the SFRs and RAM are also retained. The status of the Port pins during Idle mode is detailed in Table 42. Entering Idle Mode To enter Idle mode, you must set the IDL bit in PCON register (see Table 43). The AT8xC51SND1A enters Idle mode upon execution of the instruction that sets IDL bit. The instruction that sets IDL bit is the last instruction executed. Note: Exiting Idle Mode If IDL bit and PD bit are set simultaneously, the AT8xC51SND1A enters Power-down mode. Then it does not go in Idle mode when exiting Power-down mode. There are two ways to exit Idle mode: 1. Generate an enabled interrupt. - Hardware clears IDL bit in PCON register which restores the clock to the CPU. Execution resumes with the interrupt service routine. Upon completion of the interrupt service routine, program execution resumes with the instruction immediately following the instruction that activated Idle mode. The general-purpose flags (GF1 and GF0 in PCON register) may be used to indicate whether an interrupt occurred during normal operation or during Idle mode. When Idle mode is exited by an interrupt, the interrupt service routine may examine GF1 and GF0. 2. Generate a reset. - Note: Power-down Mode 42 During the time that execution resumes, the internal RAM cannot be accessed; however, it is possible for the Port pins to be accessed. To avoid unexpected outputs at the Port pins, the instruction immediately following the instruction that activated Idle mode should not write to a Port pin or to the external RAM. The Power-down mode places the AT8xC51SND1A in a very low power state. Powerdown mode stops the oscillator and freezes all clocks at known states (refer to the Section "Oscillator", page 4). The CPU status prior to entering Power-down mode is preserved, i.e., the program counter, program status word register retain their data for the duration of Power-down mode. In addition, the SFRs and RAM contents are preserved. The status of the Port pins during Power-down mode is detailed in Table 42. Note: Entering Power-down Mode A logic high on the RST pin clears IDL bit in PCON register directly and asynchronously. This restores the clock to the CPU. Program execution momentarily resumes with the instruction immediately following the instruction that activated the Idle mode and may continue for a number of clock cycles before the internal reset algorithm takes control. Reset initializes the AT8xC51SND1A and vectors the CPU to address C:0000h. VDD may be reduced to as low as VRET during Power-down mode to further reduce power dissipation. Take care, however, that VDD is not reduced until Power-down mode is invoked. To enter Power-down mode, set PD bit in PCON register. The AT8xC51SND1A enters the Power-down mode upon execution of the instruction that sets PD bit. The instruction that sets PD bit is the last instruction executed. AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Exiting Power-down Mode If VDD was reduced during the Power-down mode, do not exit Power-down mode until VDD is restored to the normal operating level. There are two ways to exit the Power-down mode: 1. Generate an enabled external interrupt. - Note: The AT8xC51SND1A provides capability to exit from Power-down using INT0#, INT1#, and KIN3:0 inputs. In addition, using KIN input provides high or low level exit capability (see Section "Keyboard Interface", page 157). Hardware clears PD bit in PCON register which starts the oscillator and restores the clocks to the CPU and peripherals. Using INTx# input, execution resumes when the input is released (see Figure 13) while using KINx input, execution resumes after counting 1024 clock ensuring the oscillator is restarted properly (see Figure 14). This behavior is necessary for decoding the key while it is still pressed. In both cases, execution resumes with the interrupt service routine. Upon completion of the interrupt service routine, program execution resumes with the instruction immediately following the instruction that activated Power-down mode. 1. The external interrupt used to exit Power-down mode must be configured as level sensitive (INT0# and INT1#) and must be assigned the highest priority. In addition, the duration of the interrupt must be long enough to allow the oscillator to stabilize. The execution will only resume when the interrupt is deasserted. 2. Exit from power-down by external interrupt does not affect the SFRs nor the internal RAM content. Figure 13. Power-down Exit Waveform Using INT1:0# INT1:0# OSC Active phase Power-down phase Oscillator restart phase Active phase Figure 14. Power-down Exit Waveform Using KIN3:0 KIN3:01 OSC Active phase Note: Power-down phase 1024 clock count Active phase 1. KIN3:0 can be high or low level triggered. 2. Generate a reset. - A logic high on the RST pin clears PD bit in PCON register directly and asynchronously. This starts the oscillator and restores the clock to the CPU and peripherals. Program execution momentarily resumes with the instruction immediately following the instruction that activated Power-down mode and may continue for a number of clock cycles before the internal 43 4109C-8051-03/02 reset algorithm takes control. Reset initializes the AT8xC51SND1A and vectors the CPU to address 0000h. Notes: Registers 1. During the time that execution resumes, the internal RAM cannot be accessed; however, it is possible for the Port pins to be accessed. To avoid unexpected outputs at the Port pins, the instruction immediately following the instruction that activated the Power-down mode should not write to a Port pin or to the external RAM. 2. Exit from power-down by reset redefines all the SFRs, but does not affect the internal RAM content. Table 43. PCON Register PCON (S:87h) - Power configuration Register 7 6 5 4 3 2 1 0 - - - - GF1 GF0 PD IDL Bit Number Bit Mnemonic Description Reserved The value read from these bits is indeterminate. Do not set these bits. 7-4 - 3 GF1 General-purpose flag 1 One use is to indicate whether an interrupt occurred during normal operation or during Idle mode. 2 GF0 General-purpose flag 0 One use is to indicate whether an interrupt occurred during normal operation or during Idle mode. PD Power-down Mode bit Cleared by hardware when an interrupt or reset occurs. Set to activate the Power-down mode. If IDL and PD are both set, PD takes precedence. IDL Idle Mode bit Cleared by hardware when an interrupt or reset occurs. Set to activate the Idle mode. If IDL and PD are both set, PD takes precedence. 1 0 Reset Value = XXXX 0000b 44 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Timers/Counters The AT8xC51SND1A implements two general-purpose, 16-bit Timers/Counters. They are identified as Timer 0 and Timer 1, and can be independently configured to operate in a variety of modes as a Timer or as an event Counter. When operating as a Timer, the Timer/Counter runs for a programmed length of time, then issues an interrupt request. When operating as a Counter, the Timer/Counter counts negative transitions on an external pin. After a preset number of counts, the Counter issues an interrupt request. The various operating modes of each Timer/Counter are described in the following sections. Timer/Counter Operations For instance, a basic operation is Timer registers THx and TLx (x = 0, 1) connected in cascade to form a 16-bit Timer. Setting the run control bit (TRx) in TCON register (see Table 44) turns the Timer on by allowing the selected input to increment TLx. When TLx overflows it increments THx; when THx overflows it sets the Timer overflow flag (TFx) in TCON register. Setting the TRx does not clear the THx and TLx Timer registers. Timer registers can be accessed to obtain the current count or to enter preset values. They can be read at any time but TRx bit must be cleared to preset their values, otherwise the behavior of the Timer/Counter is unpredictable. The C/Tx# control bit selects Timer operation or Counter operation by selecting the divided-down peripheral clock or external pin Tx as the source for the counted signal. TRx bit must be cleared when changing the mode of operation, otherwise the behavior of the Timer/Counter is unpredictable. For Timer operation (C/Tx# = 0), the Timer register counts the divided-down peripheral clock. The Timer register is incremented once every peripheral cycle (6 peripheral clock periods). The Timer clock rate is FPER/6, i.e. FOSC/12 in standard mode or FOSC/6 in X2 mode. For Counter operation (C/Tx# = 1), the Timer register counts the negative transitions on the Tx external input pin. The external input is sampled every peripheral cycles. When the sample is high in one cycle and low in the next one, the Counter is incremented. Since it takes 2 cycles (12 peripheral clock periods) to recognize a negative transition, the maximum count rate is FPER/12, i.e. F OSC/24 in standard mode or FOSC/12 in X2 mode. There are no restrictions on the duty cycle of the external input signal, but to ensure that a given level is sampled at least once before it changes, it should be held for at least one full peripheral cycle. Timer Clock Controller As shown in Figure 15 the Timer 0 (FT0) and Timer 1 (FT1) clocks are derived from either the peripheral clock (FPER) or the oscillator clock (FOSC) depending on the T0X2 and T1X2 bits in CKCON register. These clocks are issued from the Clock Controller block as detailed in Section "CKCON Register", page 7. When T0X2 or T1X2 bit is set, the Timer 0 or Timer 1 clock frequency is fixed and equal to the oscillator clock frequency divided by 2. When cleared, the Timer clock frequency is equal to the oscillator clock frequency divided by 2 in standard mode or to the oscillator clock frequency in X2 mode. 45 4109C-8051-03/02 Figure 15. Timer 0 and Timer 1 Clock Controller and Symbols PER CLOCK 0 Timer 0 Clock PER CLOCK 0 Timer 1 Clock 1 OSC CLOCK 1 OSC CLOCK /2 T0X2 T1X2 CKCON.1 CKCON.2 TIM0 CLOCK TIM1 CLOCK Timer 0 Clock Symbol Timer 0 /2 Timer 1 Clock Symbol Timer 0 functions as either a Timer or event Counter in four modes of operation. Figure 16 to Figure 22 show the logical configuration of each mode. Timer 0 is controlled by the four lower bits of TMOD register (see Table 45) and bits 0, 1, 4 and 5 of TCON register (see Table 44). TMOD register selects the method of Timer gating (GATE0), Timer or Counter operation (T/C0#) and mode of operation (M10 and M00). TCON register provides Timer 0 control functions: overflow flag (TF0), run control bit (TR0), interrupt flag (IE0) and interrupt type control bit (IT0). For normal Timer operation (GATE0 = 0), setting TR0 allows TL0 to be incremented by the selected input. Setting GATE0 and TR0 allows external pin INT0# to control Timer operation. Timer 0 overflow (count rolls over from all 1s to all 0s) sets TF0 flag generating an interrupt request. It is important to stop Timer/Counter before changing mode. Mode 0 (13-bit Timer) Mode 0 configures Timer 0 as a 13-bit Timer which is set up as an 8-bit Timer (TH0 register) with a modulo 32 prescaler implemented with the lower five bits of TL0 register (see Figure 16). The upper three bits of TL0 register are indeterminate and should be ignored. Prescaler overflow increments TH0 register. Figure 17 gives the overflow period calculation formula. Figure 16. Timer/Counter x (x = 0 or 1) in Mode 0 TIMx CLOCK /6 0 TLx (5 bits) 1 THx (8 bits) Overflow TFx TCON reg Timer x Interrupt Request Tx C/Tx# TMOD reg INTx# GATEx TMOD reg TRx TCON reg Figure 17. Mode 0 Overflow Period Formula TFxPER= 46 6 (16384 - (THx, TLx)) FTIMx AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Mode 1 (16-bit Timer) Mode 1 configures Timer 0 as a 16-bit Timer with TH0 and TL0 registers connected in cascade (see Figure 18). The selected input increments TL0 register. Figure 19 gives the overflow period calculation formula when in timer mode. Figure 18. Timer/Counter x (x = 0 or 1) in Mode 1 TIMx CLOCK /6 0 THx (8 bits) 1 TLx (8 bits) Overflow TFx TCON reg Tx Timer x Interrupt Request C/Tx# TMOD reg INTx# GATEx TRx TMOD reg TCON reg Figure 19. Mode 1 Overflow Period Formula TFxPER= Mode 2 (8-bit Timer with AutoReload) 6 (65536 - (THx, TLx)) FTIMx Mode 2 configures Timer 0 as an 8-bit Timer (TL0 register) that automatically reloads from TH0 register (see Table 46). TL0 overflow sets TF0 flag in TCON register and reloads TL0 with the contents of TH0, which is preset by software. When the interrupt request is serviced, hardware clears TF0. The reload leaves TH0 unchanged. The next reload value may be changed at any time by writing it to TH0 register. Figure 21 gives the autoreload period calculation formula when in timer mode. Figure 20. Timer/Counter x (x = 0 or 1) in Mode 2 TIMx CLOCK /6 0 TLx (8 bits) 1 Tx Overflow TFx TCON reg Timer x Interrupt Request C/Tx# TMOD reg INTx# GATEx TMOD reg THx (8 bits) TRx TCON reg Figure 21. Mode 2 Autoreload Period Formula TFxPER= Mode 3 (Two 8-bit Timers) 6 (256 - THx) FTIMx Mode 3 configures Timer 0 such that registers TL0 and TH0 operate as separate 8-bit Timers (see Figure 22). This mode is provided for applications requiring an additional 8bit Timer or Counter. TL0 uses the Timer 0 control bits C/T0# and GATE0 in TMOD register, and TR0 and TF0 in TCON register in the normal manner. TH0 is locked into a Timer function (counting FT1/6) and takes over use of the Timer 1 interrupt (TF1) and run control (TR1) bits. Thus, operation of Timer 1 is restricted when Timer 0 is in mode 3. Figure 21 gives the autoreload period calculation formulas for both TF0 and TF1 flags. 47 4109C-8051-03/02 Figure 22. Timer/Counter 0 in Mode 3: Two 8-bit Counters TIM0 CLOCK /6 0 1 TL0 (8 bits) Overflow TH0 (8 bits) Overflow TF0 TCON.5 T0 Timer 0 Interrupt Request C/T0# TMOD.2 INT0# GATE0 TR0 TMOD.3 TIM0 CLOCK TCON.4 /6 TF1 TCON.7 Timer 1 Interrupt Request TR1 TCON.6 Figure 23. Mode 3 Overflow Period Formula TF0PER = Timer 1 TF1PER = 6 (256 - TH0) FTIM0 Timer 1 is identical to Timer 0 excepted for Mode 3 which is a hold-count mode. Following comments help to understand the differences: Mode 0 (13-bit Timer) 48 6 (256 - TL0) FTIM0 * Timer 1 functions as either a Timer or event Counter in three modes of operation. Figure 16 to Figure 20 show the logical configuration for modes 0, 1, and 2. Timer 1's mode 3 is a hold-count mode. * Timer 1 is controlled by the four high-order bits of TMOD register (see Figure 45) and bits 2, 3, 6 and 7 of TCON register (see Figure 44). TMOD register selects the method of Timer gating (GATE1), Timer or Counter operation (C/T1#) and mode of operation (M11 and M01). TCON register provides Timer 1 control functions: overflow flag (TF1), run control bit (TR1), interrupt flag (IE1) and interrupt type control bit (IT1). * Timer 1 can serve as the Baud Rate Generator for the Serial Port. Mode 2 is best suited for this purpose. * For normal Timer operation (GATE1 = 0), setting TR1 allows TL1 to be incremented by the selected input. Setting GATE1 and TR1 allows external pin INT1# to control Timer operation. * Timer 1 overflow (count rolls over from all 1s to all 0s) sets the TF1 flag generating an interrupt request. * When Timer 0 is in mode 3, it uses Timer 1's overflow flag (TF1) and run control bit (TR1). For this situation, use Timer 1 only for applications that do not require an interrupt (such as a Baud Rate Generator for the Serial Port) and switch Timer 1 in and out of mode 3 to turn it off and on. * It is important to stop the Timer/Counter before changing modes. Mode 0 configures Timer 1 as a 13-bit Timer, which is set up as an 8-bit Timer (TH1 register) with a modulo-32 prescaler implemented with the lower 5 bits of the TL1 register (see Figure 16). The upper 3 bits of TL1 register are ignored. Prescaler overflow increments TH1 register. AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Mode 1 (16-bit Timer) Mode 1 configures Timer 1 as a 16-bit Timer with TH1 and TL1 registers connected in cascade (see Figure 18). The selected input increments TL1 register. Mode 2 (8-bit Timer with AutoReload) Mode 2 configures Timer 1 as an 8-bit Timer (TL1 register) with automatic reload from TH1 register on overflow (see Figure 20). TL1 overflow sets TF1 flag in TCON register and reloads TL1 with the contents of TH1, which is preset by software. The reload leaves TH1 unchanged. Mode 3 (Halt) Placing Timer 1 in mode 3 causes it to halt and hold its count. This can be used to halt Timer 1 when TR1 run control bit is not available i.e. when Timer 0 is in mode 3. Interrupt Each Timer handles one interrupt source that is the timer overflow flag TF0 or TF1. This flag is set every time an overflow occurs. Flags are cleared when vectoring to the Timer interrupt routine. Interrupts are enabled by setting ETx bit in IEN0 register. This assumes interrupts are globally enabled by setting EA bit in IEN0 register. Figure 24. Timer Interrupt System Timer 0 Interrupt Request TF0 TCON.5 ET0 IEN0.1 Timer 1 Interrupt Request TF1 TCON.7 ET1 IEN0.3 49 4109C-8051-03/02 Registers Table 44. TCON Register TCON (S:88h) - Timer/Counter Control Register 7 6 5 4 3 2 1 0 TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0 Bit Number Bit Mnemonic Description 7 TF1 Timer 1 Overflow Flag Cleared by hardware when processor vectors to interrupt routine. Set by hardware on Timer/Counter overflow, when Timer 1 register overflows. 6 TR1 Timer 1 Run Control Bit Clear to turn off Timer/Counter 1. Set to turn on Timer/Counter 1. 5 TF0 Timer 0 Overflow Flag Cleared by hardware when processor vectors to interrupt routine. Set by hardware on Timer/Counter overflow, when Timer 0 register overflows. 4 TR0 Timer 0 Run Control Bit Clear to turn off Timer/Counter 0. Set to turn on Timer/Counter 0. 3 IE1 Interrupt 1 Edge Flag Cleared by hardware when interrupt is processed if edge-triggered (see IT1). Set by hardware when external interrupt is detected on INT1# pin. 2 IT1 Interrupt 1 Type Control Bit Clear to select low level active (level triggered) for external interrupt 1 (INT1#). Set to select falling edge active (edge triggered) for external interrupt 1. 1 IE0 Interrupt 0 Edge Flag Cleared by hardware when interrupt is processed if edge-triggered (see IT0). Set by hardware when external interrupt is detected on INT0# pin. 0 IT0 Interrupt 0 Type Control Bit Clear to select low level active (level triggered) for external interrupt 0 (INT0#). Set to select falling edge active (edge triggered) for external interrupt 0. Reset Value = 0000 0000b 50 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 45. TMOD Register TMOD (S:89h) - Timer/Counter Mode Control Register 7 6 5 4 3 2 1 0 GATE1 C/T1# M11 M01 GATE0 C/T0# M10 M00 Bit Bit Number Mnemonic Description 7 GATE1 Timer 1 Gating Control Bit Clear to enable Timer 1 whenever TR1 bit is set. Set to enable Timer 1 only while INT1# pin is high and TR1 bit is set. 6 C/T1# Timer 1 Counter/Timer Select Bit Clear for Timer operation: Timer 1 counts the divided-down system clock. Set for Counter operation: Timer 1 counts negative transitions on external pin T1. 5 M11 4 M01 Timer 1 Mode Select Bits M11 M01 Operating mode 0 0 Mode 0: 8-bit Timer/Counter (TH1) with 5-bit prescaler (TL1). 0 1 Mode 1: 16-bit Timer/Counter. 1 0 Mode 2: 8-bit auto-reload Timer/Counter (TL1).(1) 1 1 Mode 3: Timer 1 halted. Retains count. 3 GATE0 Timer 0 Gating Control Bit Clear to enable Timer 0 whenever TR0 bit is set. Set to enable Timer/Counter 0 only while INT0# pin is high and TR0 bit is set. 2 C/T0# Timer 0 Counter/Timer Select Bit Clear for Timer operation: Timer 0 counts the divided-down system clock. Set for Counter operation: Timer 0 counts negative transitions on external pin T0. M10 1 Timer 0 Mode Select Bit M10 M00 Operating mode 0 0 Mode 0: 8-bit Timer/Counter (TH0) with 5-bit prescaler (TL0). 0 1 Mode 1: 16-bit Timer/Counter. 1 0 Mode 2: 8-bit auto-reload Timer/Counter (TL0).(2) M00 0 1 1 Mode 3: TL0 is an 8-bit Timer/Counter. TH0 is an 8-bit Timer using Timer 1's TR0 and TF0 bits. Notes: 1. Reloaded from TH1 at overflow. 2. Reloaded from TH0 at overflow. Reset Value = 0000 0000b Table 46. TH0 Register TH0 (S:8Ch) - Timer 0 High Byte Register 7 6 5 4 3 2 1 0 - - - - - - - - Bit Number 7:0 Bit Mnemonic Description High Byte of Timer 0. Reset Value = 0000 0000b 51 4109C-8051-03/02 Table 47. TL0 Register TL0 (S:8Ah) - Timer 0 Low Byte Register 7 6 5 4 3 2 1 0 - - - - - - - - Bit Number Bit Mnemonic Description 7:0 Low Byte of Timer 0. Reset Value = 0000 0000b Table 48. TH1 Register TH1 (S:8Dh) - Timer 1 High Byte Register 7 6 5 4 3 2 1 0 - - - - - - - - Bit Number Bit Mnemonic Description 7:0 High Byte of Timer 1. Reset Value = 0000 0000b Table 49. TL1 Register TL1 (S:8Bh) - Timer 1 Low Byte Register 7 6 5 4 3 2 1 0 - - - - - - - - Bit Number 7:0 Bit Mnemonic Description Low Byte of Timer 1. Reset Value = 0000 0000b 52 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Watchdog Timer The AT8xC51SND1A implements a hardware Watchdog Timer (WDT) that automatically resets the chip if it is allowed to time out. The WDT provides a means of recovering from routines that do not complete successfully due to software or hardware malfunctions. Description The WDT consists of a 14-bit prescaler followed by a 7-bit programmable counter. As shown in Figure 25, the 14-bit prescaler is fed by the WDT clock detailed in Section "Watchdog Clock Controller", page 53. The Watchdog Timer Reset register (WDTRST, see Table 51) provides control access to the WDT, while the Watchdog Timer Program register (WDTPRG, see Figure 12) provides time-out period programming. Three operations control the WDT: * Chip reset clears and disables the WDT. * Programming the time-out value to the WDTPRG register. * Writing a specific two-byte sequence to the WDTRST register clears and enables the WDT. Figure 25. WDT Block Diagram WDT CLOCK 14-bit Prescaler /6 7-bit Counter OV RST RST To internal reset SET WTO2:0 1Eh-E1h Decoder System Reset RST WDTPRG.2:0 EN MATCH OSC CLOCK Pulse Generator RST WDTRST Watchdog Clock Controller As shown in Figure 26 the WDT clock (FWDT ) is derived from either the peripheral clock (FPER) or the oscillator clock (FOSC) depending on the WTX2 bit in CKCON register. These clocks are issued from the Clock Controller block as detailed in Section "Clock Controller", page 4. When WTX2 bit is set, the WDT clock frequency is fixed and equal to the oscillator clock frequency divided by 2. When cleared, the WDT clock frequency is equal to the oscillator clock frequency divided by 2 in standard mode or to the oscillator clock frequency in X2 mode. Figure 26. WDT Clock Controller and Symbol PER CLOCK 0 WDT Clock 1 OSC CLOCK /2 WDT CLOCK WDT Clock Symbol WTX2 CKCON.6 53 4109C-8051-03/02 Watchdog Operation After reset, the WDT is disabled. The WDT is enabled by writing the sequence 1Eh and E1h into the WDTRST register. As soon as it is enabled, there is no way except the chip reset to disable it. If it is not cleared using the previous sequence, the WDT overflows and forces a chip reset. This overflow generates a high level 96 oscillator periods pulse on the RST pin to globally reset the application. The WDT time-out period can be adjusted using WTO2:0 bits located in the WDTPRG register accordingly to the formula shown in Figure 11. In this formula, WTOval represents the decimal value of WTO2:0 bits. Table 50 reports the time-out period depending on the WDT frequency. Figure 11. WDT Time-Out Formula 6 ((214 2WTOval) - 1) FWDT WDTTO = Table 50. WDT Time-Out Computation FWDT 8 MHz (1) 10 MHz (1) 12 MHz(2) 16 MHz(2) 20 MHz(2) WTO2 WTO1 WTO0 0 0 0 16.38 ms 12.28 ms 9.83 ms 8.19 ms 6.14 ms 4.92 ms 0 0 1 32.77 ms 24.57 ms 19.66 ms 16.38 ms 12.28 ms 9.83 ms 0 1 0 65.54 ms 49.14 ms 39.32 ms 32.77 ms 24.57 ms 19.66 ms 0 1 1 131.07 ms 98.28 ms 78.64 ms 65.54 ms 49.14 ms 39.32 ms 1 0 0 262.14 ms 196.56 ms 157.29 ms 131.07 ms 98.28 ms 78.64 ms 1 0 1 524.29 ms 393.12 ms 314.57 ms 262.14 ms 196.56 ms 157.29 ms 1 1 0 1.05 s 786.24 ms 629.15 ms 524.29 ms 393.12 ms 314.57 ms 1 1 1 2.10 s 1.57 s 1.26 s 1.05 s 786.24 ms 629.15 ms Notes: 6 MHz (1) 1. These frequencies are achieved in X1 mode, FWDT = F OSC / 2. 2. These frequencies are achieved in X2 mode, FWDT = F OSC. WDT Behavior During Idle and Power-down Modes Operation of the WDT during power reduction modes deserves special attention. The WDT continues to count while the AT8xC51SND1A is in Idle mode. This means that you must dedicate some internal or external hardware to service the WDT during Idle mode. One approach is to use a peripheral Timer to generate an interrupt request when the Timer overflows. The interrupt service routine then clears the WDT, reloads the peripheral Timer for the next service period and puts the AT8xC51SND1A back into Idle mode. The Power-down mode stops all phase clocks. This causes the WDT to stop counting and to hold its count. The WDT resumes counting from where it left off if the Powerdown mode is terminated by INT0#, INT1# or keyboard interrupt. To ensure that the WDT does not overflow shortly after exiting the Power-down mode, it is recommended to clear the WDT just before entering Power-down mode. The WDT is cleared and disabled if the Power-down mode is terminated by a reset. 54 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Registers Table 51. WDTRST Register WDTRST (S:A6h Write only) - Watchdog Timer Reset Register 7 6 5 4 3 2 1 0 - - - - - - - - Bit Number 7-0 Bit Mnemonic Description - Watchdog Control Value. Reset Value = XXXX XXXXb Figure 12. WDTPRG Register WDTPRG (S:A7h) - Watchdog Timer Program Register 7 6 5 4 3 2 1 0 - - - - - WTO2 WTO1 WTO0 Bit Number Bit Mnemonic Description 7-3 - 2-0 WTO2:0 Reserved The value read from these bits is indeterminate. Do not set these bits. Watchdog Timer Time-Out Selection Bits Refer to Table 50 for time-out periods. Reset Value = XXXX X000b= 55 4109C-8051-03/02 MP3 Decoder The AT8xC51SND1A implements a MPEG I/II audio layer 3 decoder better known as MP3 decoder. In MPEG I (ISO 11172-3) three layers of compression have been standardized supporting three sampling frequencies: 48, 44.1, and 32 kHz. Among these layers, layer 3 allows highest compression rate of about 12:1 while still maintaining CD audio quality. For example, 3 minutes of CD audio (16-bit PCM, 44.1 kHz) data, which needs about 32M Bytes of storage, can be encoded into only 2.7M Bytes of MPEG I audio layer 3 data. In MPEG II (ISO 13818-3), three additional sampling frequencies: 24, 22.05, and 16 kHz are supported for low bit rates applications. The AT8xC51SND1A can decode in real-time the MPEG I audio layer 3 encoded data into a PCM audio data, and also supports MPEG II audio layer 3 additional frequencies. Additional features are supported by the AT8xC51SND1A MP3 decoder such as volume control, bass, medium, and treble controls, bass boost effect and ancillary data extraction. Decoder Description The C51 core interfaces to the MP3 decoder through nine special function registers: MP3CON, the MP3 Control register (see Table 57); MP3STA, the MP3 Status register (see Table 58); MP3DAT, the MP3 Data register (see Table 59); MP3ANC, the Ancillary Data register (see Table 60); MP3VOL and MP3VOR, the MP3 Volume Left and Right Control registers (see Table 61 and Table 62); MP3BAS, MP3MED, and MP3TRE, the MP3 Bass, Medium, and Treble Control registers (see Table 63, Table 64, and Table 65); and MPCLK, the MP3 Clock Divider register (see Table 66). Figure 27 shows the MP3 decoder block diagram. Figure 27. MP3 Decoder Block Diagram Audio Data From C51 8 1K bytes Frame Buffer MP3DAT Header Checker Huffman Decoder MPxREQ ERRxxx MPFS1:0 MPVER MP3STA1.n MP3STA.5:3 MP3STA.2:1 MP3STA.0 Dequantizer Stereo Processor Side Information MP3 CLOCK Ancillary Buffer MP3ANC MPEN MP3CON.7 Anti-Aliasing MPBBST MP3CON.6 56 MP3VOL IMDCT MP3VOR MP3BAS Sub-band Synthesis MP3MED 16 Decoded Data To Audio Interface MP3TRE AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A MPEG I Limitations In order to optimize the MP3 decoder, in MPEG I version some bit rates are not achievable due to frame size for such bit rates. Table 52 shows the available decoded bit rates depending on the sampling frequency. All the available bit rates are achievable in MPEG II version. Table 52. MPEG I Decoding Bit Rates Description Bit Rate (kHz) Sample Frequency (kHz) 32 40 48 56 64 80 96 112 128 160 192 224 32 X X X X X X X X X X X X 44.1 X X X X X X X X X X X X X 48 X X X X X X X X X X X X X MP3 Data 256 320 X The MP3 decoder does not start any frame decoding before having a complete frame in its input buffer(1). In order to manage the load of MP3 data in the frame buffer, a hardware handshake consisting of data request and data acknowledgment is implemented. Each time the MP3 decoder needs MP3 data, it sets the MPREQ and MPFREQ flags respectively in MP3STA and MP3STA1 registers. MPREQ flag can generate an interrupt if enabled as explained in Section . The CPU must then load data in the buffer by writing it through MP3DAT register thus acknowledging the previous request. As shown in Figure 28, the MPFREQ flag remains set while data is requested by the decoder. It is cleared when no more data is requested and set again when new data are requested. Note: 1. The first request after enable, consists in 1024 bytes of data to fill in the input buffer. Figure 28. Data Timing Diagram MPREQ Flag Cleared when reading MP3STA MPFREQ Flag Write to MP3DAT MP3 Clock The MP3 decoder clock is generated by division of the PLL clock. The division factor is given by MPCD4:0 bits in MP3CLK register. Figure 29 shows the MP3 decoder clock generator and its calculation formula. The MP3 decoder clock frequency depends only on the incoming MP3 frames. Figure 29. MP3 Clock Generator and Symbol MP3CLK PLL CLOCK MPCD4:0 MP3 Decoder Clock PL Lclk M P3clk = ---------------------------MPCD + 1 MP3 CLOCK MP3 Clock Symbol As soon as the frame header has been decoded and the MPEG version extracted, the minimum MP3 input frequency must be programmed according to Table 53. 57 4109C-8051-03/02 Table 53. MP3 Clock Frequency MPEG Version Minimum MP3 Clock (MHz) I 21 II 10.5 Audio Controls Volume Control The MP3 decoder implements volume control on both right and left channels. The MP3VOR and MP3VOL registers allow a 32-step volume control according to Table 54. Table 54. Volume Control Equalization Control VOL4:0 or VOR4:0 Volume Gain (dB) 00000 Mute 00001 -33 00010 -27 11110 -1.5 11111 0 Sound can be adjusted using a 3-band equalizer: a bass band under 680 Hz, a medium band from 680 Hz to 4080 Hz and a treble band over 4080 kHz. The MP3BAS, MP3MED, and MP3TRE registers allow a 32-step gain control in each band according to Table 55. Table 55. Bass, Medium, Treble Control Special Effect 58 BAS4:0 or MED4:0 or TRE4:0 Gain (dB) 00000 - 00001 -14 00010 -10 11110 +1 11111 +1.5 The MPBBST bit in MP3CON register allows enabling of a bass boost effect with the following characteristics: gain increase of +15 dB in the frequency under 120 Hz and gain increase of +6 dB in the frequency range 120 to 240 Hz. AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Decoding Errors The three different errors that can appear during frame processing are detailed in the following sections. All these errors can trigger an interrupt as explained in Section "Interrupt", page 60. Layer Error The ERRSYN flag in MP3STA is set when a non-supported layer is decoded in the header of the frame that has been sent to the decoder. Synchronization Error The ERRSYN flag in MP3STA is set when no synchronization pattern is found in the data that have been sent to the decoder. CRC Error When the CRC of a frame does not match the one calculated, the flag ERRCRC in MP3STA is set. In this case, depending on the CRCEN bit in MP3CON, the frame is played or rejected. In both cases, noise may appear at audio output. Frame Information The MP3 frame header contains information on the audio data contained in the frame. These informations are made available in the MP3STA register for you information. MPVER and MPFS1:0 bits allow decoding of the sampling frequency according to Table 56. MPVER bit gives the MPEG version (2 or 1). Table 56. MP3 Frame Frequency Sampling Ancillary Data MPVER MPFS1 MPFS0 Fs (kHz) 0 0 0 22.05 (MPEG II) 0 0 1 24 (MPEG II) 0 1 0 16 (MPEG II) 0 1 1 Reserved 1 0 0 44.1 (MPEG I) 1 0 1 48 (MPEG I) 1 1 0 32 (MPEG I) 1 1 1 Reserved MP3 frames also contain data bits called ancillary data. These data are made available in the MP3ANC register for each frame. As shown in Figure 13, the ancillary data are available by bytes when MPANC flag in MP3STA register is set. MPANC flag is set when the ancillary buffer is not empty (at least one ancillary data is available) and is cleared only when there is no more ancillary data in the buffer. This flag can generate an interrupt as explained in Section "Interrupt", page 60. When set, software must read all bytes to empty the ancillary buffer. Figure 13. Ancillary Data Block Diagram Ancillary Data To C51 8 MP3ANC 8 7-Byte Ancillary Buffer MPANC MP3STA.7 59 4109C-8051-03/02 Interrupt Description As shown in Figure 30, the MP3 decoder implements five interrupt sources reported in ERRCRC, ERRSYN, ERRLAY, MPREQ, and MPANC flags in MP3STA register. All these sources are maskable separately using MSKCRC, MSKSYN, MSKLAY, MSKREQ, and MSKANC mask bits respectively in MP3CON register. The MP3 interrupt is enabled by setting ESMP3 bit in IEN0 register. This assumes interrupts are globally enabled by setting EA bit in IEN0 register. All interrupt flags but MPREQ and MPANC are cleared when reading MP3STA register. The MPREQ flag is cleared by hardware when no more data is requested (see Figure 28) and MPANC flag is cleared by hardware when the ancillary buffer becomes empty. Figure 30. MP3 Decoder Interrupt System MPANC MP3STA.7 MSKANC MP3CON.4 MPREQ MP3STA.6 MSKREQ ERRLAY MP3 Decoder Interrupt Request MP3CON.3 MP3STA.5 ERRSYN MSKLAY EMP3 MP3CON.2 IEN0.5 MP3STA.4 MSKSYN ERRCRC MP3CON.1 MP3STA.3 MSKCRC MP3CON.0 Management 60 Reading the MP3STA register automatically clears the interrupt flags (acknowledgment) except the MPREQ and MPANC flags. This implies that register content must be saved and tested, interrupt flag by interrupt flag to be sure not to forget any interrupts. AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Figure 31. MP3 Interrupt Service Routine Flow MP3 Decoder ISR Read MP3STA Data Request? MPFREQ = 1? Data Request Handler Write MP3 Data to MP3DAT Ancillary Data?(1) MPANC = 1? Ancillary Data Handler Sync Error?(1) ERRSYN = 1? Read ANN2:0 Ancillary Bytes From MP3ANC Synchro Error Handler Reload MP3 Frame Through MP3DAT Layer Error?(1) ERRSYN = 1? Layer Error Handler CRC Error Handler Load New MP3 Frame Through MP3DAT Note: 1. Test these bits only if needed (unmasked interrupt). 61 4109C-8051-03/02 Registers Table 57. MP3CON Register MP3CON (S:AAh) - MP3 Decoder Control Register 7 6 5 4 3 2 1 0 MPEN MPBBST CRCEN MSKANC MSKREQ MSKLAY MSKSYN MSKCRC Bit Number Bit Mnemonic Description MP3 Decoder Enable Bit Set to enable the MP3 decoder. Clear to disable the MP3 decoder. 7 MPEN 6 MPBBST Bass Boost Bit Set to enable the bass boost sound effect. Clear to disable the bass boost sound effect. 5 CRCEN CRC Check Enable Bit Set to enable processing of frame that contains CRC error. Frame is played whatever the error. Clear to disable processing of frame that contains CRC error. Frame is skipped. 4 MSKANC MPANC Flag Mask Bit Set to prevent the MPANC flag from generating a MP3 interrupt. Clear to allow the MPANC flag to generate a MP3 interrupt. 3 MSKREQ MPREQ Flag Mask Bit Set to prevent the MPREQ flag from generating a MP3 interrupt. Clear to allow the MPREQ flag to generate a MP3 interrupt. 2 MSKLAY ERRLAY Flag Mask Bit Set to prevent the ERRLAY flag from generating a MP3 interrupt. Clear to allow the ERRLAY flag to generate a MP3 interrupt. 1 MSKSYN ERRSYN Flag Mask Bit Set to prevent the ERRSYN flag from generating a MP3 interrupt. Clear to allow the ERRSYN flag to generate a MP3 interrupt. 0 MSKCRC ERRCRC Flag Mask Bit Set to prevent the ERRCRC flag from generating a MP3 interrupt. Clear to allow the ERRCRC flag to generate a MP3 interrupt. Reset Value = 0011 1111b 62 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 58. MP3STA Register MP3STA (S:C8h Read Only) - MP3 Decoder Status Register 7 6 5 4 3 2 1 0 MPANC MPREQ ERRLAY ERRSYN ERRCRC MPFS1 MPFS0 MPVER Bit Number Bit Mnemonic Description 7 MPANC Ancillary Data Available Flag Set by hardware as soon as one ancillary data is available (buffer not empty). Cleared by hardware when no more ancillary data is available (buffer empty). 6 MPREQ MP3 Data Request Flag Set by hardware when MP3 decoder request data. Cleared when reading MP3STA. 5 ERRLAY Invalid Layer Error Flag Set by hardware when an invalid layer is encountered. Cleared when reading MP3STA. 4 ERRSYN Frame Synchronization Error Flag Set by hardware when no synchronization pattern is encountered in a frame. Cleared when reading MP3STA. 3 ERRCRC CRC Error Flag Set by hardware when a frame handling CRC is corrupted. Cleared when reading MP3STA. 2-1 MPFS1:0 Frequency Sampling Bits Refer to Table 56 for bits description. 0 MPVER MPEG Version Bit Set by the MP3 decoder when the loaded frame is a MPEG-I frame. Cleared by the MP3 decoder when the loaded frame is a MPEG-II frame. Reset Value = 0000 0001b Table 59. MP3DAT Register MP3DAT (S:ACh) - MP3 Data Register 7 6 5 4 3 2 1 0 MPD7 MPD6 MPD5 MPD4 MPD3 MPD2 MPD1 MPD0 Bit Number 7-0 Bit Mnemonic Description MPD7:0 Input Stream Data Buffer 8-bit MP3 stream data input buffer. Reset Value = 0000 0000b 63 4109C-8051-03/02 Table 60. MP3ANC Register MP3ANC (S:ADh Read Only) - MP3 Ancillary Data Register 7 6 5 4 3 2 1 0 AND7 AND6 AND5 AND4 AND3 AND2 AND1 AND0 Bit Number 7-0 Bit Mnemonic Description AND7:0 Ancillary Data Buffer MP3 ancillary data byte buffer. Reset Value = 0000 0000b Table 61. MP3VOL Register MP3VOL (S:9Eh) - MP3 Volume Left Control Register 7 6 5 4 3 2 1 0 - - - VOL4 VOL3 VOL2 VOL1 VOL0 Bit Number Bit Mnemonic Description 7-5 - Reserved The value read from these bits is always 0. Do not set these bits. 4-0 VOL4:0 Volume Left Value Refer to Table 54 for the left channel volume control description. Reset Value = 0000 0000b Table 62. MP3VOR Register MP3VOR (S:9Fh) - MP3 Volume Right Control Register 7 6 5 4 3 2 1 0 - - - VOR4 VOR3 VOR2 VOR1 VOR0 Bit Number Bit Mnemonic Description 7-5 - Reserved The value read from these bits is always 0. Do not set these bits. 4-0 VOR4:0 Volume Right Value Refer to Table 54 for the right channel volume control description. Reset Value = 0000 0000b 64 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 63. MP3BAS Register MP3BAS (S:B4h) - MP3 Bass Control Register 7 6 5 4 3 2 1 0 - - - BAS4 BAS3 BAS2 BAS1 BAS0 Bit Number Bit Mnemonic Description 7-5 - 4-0 BAS4:0 Reserved The value read from these bits is always 0. Do not set these bits. Bass Gain Value Refer to Table 55 for the bass control description. Reset Value = 0000 0000b Table 64. MP3MED Register MP3MED (S:B5h) - MP3 Medium Control Register 7 6 5 4 3 2 1 0 - - MED5 MED4 MED3 MED2 MED1 MED0 Bit Number Bit Mnemonic Description 7-6 - 5-0 MED5:0 Reserved The value read from these bits is always 0. Do not set these bits. Medium Gain Value Refer to Table 55 for the medium control description. Reset Value = 0000 0000b Table 65. MP3TRE Register MP3TRE (S:B6h) - MP3 Treble Control Register 7 6 5 4 3 2 1 0 - - TRE5 TRE4 TRE3 TRE2 TRE1 TRE0 Bit Number Bit Mnemonic Description 7-6 - 5-0 TRE5:0 Reserved The value read from these bits is always 0. Do not set these bits. Treble Gain Value Refer to Table 55 for the treble control description. Reset Value = 0000 0000b 65 4109C-8051-03/02 Table 66. MP3CLK Register MP3CLK (S:EBh) - MP3 Clock Divider Register 7 6 5 4 3 2 1 0 - - - MPCD4 MPCD3 MPCD2 MPCD1 MPCD0 Bit Number Bit Mnemonic Description 7-5 - 4-0 MPCD4:0 Reserved The value read from these bits is always 0. Do not set these bits. MP3 Decoder Clock Divider 5-bit divider for MP3 decoder clock generation. Reset Value = 0000 0000b 66 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Audio Output Interface The T8xC51SND1 implements an audio output interface allowing the audio bitstream to be output in various formats. It is compatible with right and left justification PCM and I2S formats and thanks to the on-chip PLL (see Section "Clock Controller", page 4) allows connection of almost all of the commercial audio DAC families available on the market. The audio bitstream can be from two different types: Description * The MP3 decoded bitstream coming from the MP3 decoder for playing songs. * The audio bitstream coming from the MCU for outputting voice or sounds. The C51 core interfaces to the audio interface through five special function registers: AUDCON0 and AUDCON1, the Audio Control registers (see Table 68 and Table 69); AUDSTA, the Audio Status register (see Table 70); AUDDAT, the Audio Data register (see Table 71); and AUDCLK, the Audio Clock Divider register (see Table 72). Figure 32 shows the audio interface block diagram, blocks are detailed in the following sections. Figure 32. Audio Interface Block Diagram SCLK AUD CLOCK DCLK Clock Generator 0 DSEL AUDEN 1 AUDCON1.0 Data Ready HLR DSIZ AUDCON0.0 AUDCON0.1 POL AUDCON0.2 Audio Data From MP3 Decoder 16 MP3 Buffer 16 0 16 Sample Request To MP3 Decoder DRQEN AUDCON1.6 Data Converter DOUT 1 JUST4:0 SRC AUDCON0.7:3 AUDCON1.7 SREQ Audio Data From C51 8 Audio Buffer AUDDAT AUDSTA.7 UDRN AUDSTA.6 AUBUSY DUP1:0 AUDSTA.5 AUDCON1.2:1 67 4109C-8051-03/02 Clock Generator The audio interface clock is generated by division of the PLL clock. The division factor is given by AUCD4:0 bits in CLKAUD register. Figure 14 shows the audio interface clock generator and its calculation formula. The audio interface clock frequency depends on the incoming MP3 frames and the audio DAC used. Figure 14. Audio Clock Generator and Symbol AUDCLK PLL CLOCK AUCD4:0 Audio Interface Clock AUD CLOCK Audio Clock Symbol PLLclk AUDclk = --------------------------AUCD + 1 As soon as audio interface is enabled by setting AUDEN bit in AUDCON1 register, the master clock generated by the PLL is output on the SCLK pin which is the DAC system clock. This clock is output at 256 or 384 times the sampling frequency depending on the DAC capabilities. HLR bit in AUDCON0 register must be set according to this rate for properly generating the audio bit clock on the DCLK pin and the word selection clock on the DSEL pin. These clocks are not generated when no data is available at the data converter input. For DAC compatibility, the bit clock frequency is programmable for outputting 16 bits or 32 bits per channel using the DSIZ bit in AUDCON0 register (see Section "Data Converter", page 68), and the word selection signal is programmable for outputting left channel on low or high level according to POL bit in AUDCON0 register as shown in Figure 15. Figure 15. DSEL Output Polarity Data Converter 68 POL = 0 Left Channel Right Channel POL = 1 Left Channel Right Channel The data converter block converts the audio stream input from the 16-bit parallel format to a serial format. For accepting all PCM formats and I2 S format, JUST4:0 bits in AUDCON0 register are used to shift the data output point. As shown in Figure 33, these bits allow MSB justification by setting JUST4:0 = 00000, LSB justification by setting JUST4:0 = 10000, I2S Justification by setting JUST4:0 = 00001, and more than 16-bit LSB justification by filling the low significant bits with logic 0. AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Figure 33. Audio Output Format DSEL DCLK DOUT Left Channel 1 2 3 Right Channel 13 14 15 LSB MSB B14 16 B1 1 2 3 13 14 15 LSB MSB B14 16 B1 I2S Format with DSIZ = 0 and JUST4:0 = 00001. DSEL DCLK Left Channel 1 DOUT 2 Right Channel 3 17 MSB B14 LSB 18 32 1 2 3 17 MSB B14 LSB 18 32 I2S Format with DSIZ = 1 and JUST4:0 = 00001. DSEL DCLK DOUT Left Channel 1 2 3 Right Channel 13 14 MSB B14 15 B1 16 1 2 3 13 14 LSB MSB B15 15 B1 16 LSB MSB/LSB Justified Format with DSIZ = 0 and JUST4:0 = 00000. DSEL DCLK Left Channel 1 16 DOUT 17 Right Channel 18 31 MSB B14 B1 32 1 16 LSB 17 18 31 MSB B14 B1 32 LSB 16-bit LSB Justified Format with DSIZ = 1 and JUST4:0 = 10000. DSEL DCLK DOUT Left Channel 1 15 16 MSB B16 Right Channel 30 B2 31 B1 32 LSB 1 15 16 MSB B16 30 B2 31 B1 32 LSB 18-bit LSB Justified Format with DSIZ = 1 and JUST4:0 = 01110. The data converter receives its audio stream from two sources selected by the SRC bit in AUDCON1 register. When cleared, the audio stream comes from the MP3 decoder (see Section "MP3 Decoder", page 56) for song playing. When set, the audio stream is coming from the C51 core for voice or sound playing. As soon as first audio data is input to the data converter, it enables the clock generator for generating the bit and word clocks. Audio Buffer In voice or sound playing mode, the audio stream comes from the C51 core through an audio buffer. The data is 8-bit format and is sampled at 8 kHz. The audio buffer adapts the sample format and rate. The sample format is extended to 16 bits by filling the LSB to 00h. Rate is adapted to the DAC rate by duplicating the data using DUP1:0 bits in AUDCON1 register according to Table 67. The audio buffer interfaces to the C51 core through three flags: the sample request flag (SREQ in AUDSTA register), the under-run flag (UNDR in AUDSTA register) and the busy flag (AUBUSY in AUDSTA register). SREQ and UNDR can generate an interrupt request as explained in Section "Interrupt Request", page 70. The buffer size is 8 bytes large. SREQ is set when the samples number switches from 4 to 3 and reset when the samples number switches from 4 to 5; UNDR is set when the buffer becomes empty signaling that the audio interface ran out of samples; and AUBUSY is set when the buffer is full. 69 4109C-8051-03/02 Table 67. Sample Duplication Factor DUP1 DUP0 Factor 0 0 No sample duplication, DAC rate = 8 kHz (C51 rate). 0 1 One sample duplication, DAC rate = 16 kHz (2 x C51 rate). 1 0 Two samples duplication, DAC rate = 32 kHz (4 x C51 rate). 1 1 Three samples duplication, DAC rate = 48 kHz (6 x C51 rate). MP3 Buffer In song playing mode, the audio stream comes from the MP3 decoder through a buffer. The MP3 buffer is used to store the decoded MP3 data and interfaces to the decoder through a 16-bit data input and data request signal. This signal asks for data when the buffer has enough space to receive new ones. Data request is conditioned by the DREQEN bit in AUDCON1 register. When set, the buffer requests data to the MP3 decoder. When cleared no more data is requested but data are output until the buffer becomes empty. This bit can be used to suspend the audio generation (pause mode). Interrupt Request The audio interrupt request can be generated by two sources when in C51 audio mode: a sample request when SREQ flag in AUDSTA register is set to logic 1, and an underrun condition when UDRN flag in AUDSTA register is set to logic 1. Both sources can be enabled separately by masking one of them using the MSREQ and MUDRN bits in AUDCON1 register. A global enable of the audio interface is provided by setting the EAUD bit in IEN0 register. The interrupt is requested each time one of the two sources is set to one. The source flags are cleared by writing some data in the audio buffer through AUDDAT, but the global audio interrupt flag is cleared by hardware when the interrupt service routine is executed. Figure 16. Audio Interface Interrupt System UDRN AUDSTA.6 Audio Interrupt Request MUDRN AUDCON1.4 SREQ EAUD AUDSTA.7 IEN0.6 MSREQ AUDCON1.5 MP3 Song Playing 70 In MP3 song playing mode, the operations to do are to configure the PLL and the audio interface according to the DAC selected. The audio clock is programmed to generate the 256*Fs or 384*Fs as explained in Section "Clock Generator", page 68. Figure 34 shows the configuration flow of the audio interface when in MP3 song mode. AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Figure 34. MP3 Mode Audio Configuration Flow MP3 Mode Configuration Program Audio Clock Configure Interface HLR = X DSIZ = X POL = X JUST4:0 = XXXXXb SRC = 0 Voice or Sound Playing Enable DAC System Clock AUDEN = 1 Wait For DAC Set-up Time Enable Data Request DRQEN = 1 In voice or sound playing mode, the operations required are to configure the PLL and the audio interface according to the DAC selected. The audio clock is programmed to generate the 256*Fs or 384*Fs as for the MP3 playing mode. The data flow sent by the C51 is then regulated by interrupt and data is loaded 4 bytes by 4 bytes. Figure 35 shows the configuration flow of the audio interface when in voice or sound mode. Figure 35. Voice or Sound Mode Audio Flows Voice/Song Mode Configuration Program Audio Clock Configure Interface HLR = X DSIZ = X POL = X JUST4:0 = XXXXXb DUP1:0 = XX Enable DAC system clock AUDEN = 1 Note: Audio Interrupt Service Routine Wait for DAC Enable Time Sample Request? SREQ = 1? Select Audio SRC = 1 Load 4 Samples in the Audio Buffer Under-run Condition1 Load 8 Samples in the Audio Buffer Enable Interrupt Set MSREQ & MUDRN1 EAUD = 1 1. An under-run occurrence signifies that C51 core did not respond to the previous sample request interrupt. It may never occur for a correct voice/sound generation. It is you's responsibility to mask it or not. 71 4109C-8051-03/02 Registers Table 68. AUDCON0 Register AUDCON0 (S:9Ah) - Audio Interface Control Register 0 7 6 5 4 3 2 1 0 JUST4 JUST3 JUST2 JUST1 JUST0 POL DSIZ HLR Bit Number Bit Mnemonic Description Audio Stream Justification Bits Refer to Section "Data Converter", page 68 for bits description. 7-3 JUST4:0 2 POL DSEL Signal Output Polarity Set to output the left channel on high level of DSEL output (PCM mode). Clear to output the left channel on the low level of DSEL output (I2S mode). 1 DSIZ Audio Data Size Set to select 32-bit data output format. Clear to select 16-bit data output format. 0 HLR High/Low Rate Bit Set by software when the PLL clock frequency is 384*Fs. Clear by software when the PLL clock frequency is 256*Fs. Reset Value = 0000 1000b Table 69. AUDCON1 Register AUDCON1 (S:9Bh) - Audio Interface Control Register 1 7 6 5 4 3 2 1 0 SRC DRQEN MSREQ MUDRN - DUP1 DUP0 AUDEN Bit Number Bit Mnemonic Description 7 SRC Audio Source Bit Set to select C51 as audio source for voice or sound playing. Clear to select the MP3 decoder output as audio source for song playing. 6 DRQEN MP3 Decoded Data Request Enable Bit Set to enable data request to the MP3 decoder and to start playing song. Clear to disable data request to the MP3 decoder. 5 MSREQ Audio Sample Request Flag Mask Bit Set to prevent the SREQ flag from generating an audio interrupt. Clear to allow the SREQ flag to generate an audio interrupt. 4 MUDRN Audio Sample Under-run Flag Mask Bit Set to prevent the UDRN flag from generating an audio interrupt. Clear to allow the UDRN flag to generate an audio interrupt. 3 - 2-1 DUP1:0 Audio Duplication Factor Refer to Table 67 for bits description. 0 AUDEN Audio Interface Enable Bit Set to enable the audio interface. Clear to disable the audio interface. Reserved The value read from this bit is always 0. Do not set this bit. Reset Value = 1011 0010b 72 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 70. AUDSTA Register AUDSTA (S:9Ch Read Only) - Audio Interface Status Register 7 6 5 4 3 2 1 0 SREQ UDRN AUBUSY - - - - - Bit Number Bit Mnemonic Description SREQ Audio Sample Request Flag Set in C51 audio source mode when the audio interface request samples (buffer half empty). This bit generates an interrupt if not masked and if enabled in IEN0. Cleared by hardware when samples are loaded in AUDDAT. UDRN Audio Sample Under-run Flag Set in C51 audio source mode when the audio interface runs out of samples (buffer empty). This bit generates an interrupt if not masked and if enabled in IEN0. Cleared by hardware when samples are loaded in AUDDAT. 5 AUBUSY Audio Interface Busy Bit Set in C51 audio source mode when the audio interface can not accept more sample (buffer full). Cleared by hardware when buffer is no more full. 4-0 - 7 6 Reserved The value read from these bits is always 0. Do not set these bits. Reset Value = 1100 0000b Table 71. AUDDAT Register AUDDAT (S:9Dh) - Audio Interface Data Register 7 6 5 4 3 2 1 0 AUD7 AUD6 AUD5 AUD4 AUD3 AUD2 AUD1 AUD0 Bit Number 7-0 Bit Mnemonic Description AUD7:0 Audio Data 8-bit sampling data for voice or sound playing. Reset Value = 1111 1111b Table 72. AUDCLK Register AUDCLK (S:ECh) - Audio Clock Divider Register 7 6 5 4 3 2 1 0 - - - AUCD4 AUCD3 AUCD2 AUCD1 AUCD0 Bit Number Bit Mnemonic Description 7-5 - 4-0 AUCD4:0 Reserved The value read from these bits is always 0. Do not set these bits. Audio Clock Divider 5-bit divider for audio clock generation. Reset Value = 0000 0000b 73 4109C-8051-03/02 Universal Serial Bus The AT8xC51SND1A implements an Universal Serial Bus (USB) device controller supporting Full-speed data transfer. In addition to the default control endpoint 0, it provides 3 other endpoints, which can be configured in Control, Bulk, Interrupt or Isochronous types. This allows to develop firmware conforming to most USB device classes, for example the AT8xC51SND1A supports: USB Mass Storage Class CBI Transport * USB Mass Storage Class Control/Bulk/Interrupt (CBI) Transport, Revision 1.0 - December 14, 1998 * USB Mass Storage Class Bulk-Only Transport, Revision 1.0 - September 31, 1999 * USB Device Firmware Upgrade Class, Revision 1.0 - May 13, 1999 Within the CBI framework, the Control endpoint is used to transport command blocks as well as to transport standard USB requests. One Bulk Out endpoint is used to transport data from the host to the device. One Bulk In endpoint is used to transport data from the device to the host. And one interrupt endpoint may also be used to signal command completion (protocol 0) but it is optional and may not be used (protocol 1). The following AT8xC51SND1A configuration adheres to that requirements: USB Mass Storage Class Bulk-Only Transport * Endpoint 0: 32 bytes, Control In-Out * Endpoint 1: 64 bytes, Bulk Out * Endpoint 2: 64 bytes, Bulk In * Endpoint 3: 8 bytes, Interrupt In Within the Bulk-only framework, the Control endpoint is only used to transport classspecific and standard USB requests for device set-up and configuration. One Bulk-out endpoint is used to transport commands and data from the host to the device. One Bulk in endpoint is used to transport status and data from the device to the host. No interrupt endpoint is needed. The following AT8xC51SND1A configuration adheres to that requirements: USB Device Firmware Upgrade (DFU) * Endpoint 0: 32 bytes, Control In-Out * Endpoint 1: 64 bytes, Bulk Out * Endpoint 2: 64 bytes, Bulk In * Endpoint 3: not used The USB Device Firmware Update (DFU) protocol can be used to upgrade the on-chip Flash memory of the AT89C51SND1A. This allows installing product enhancements and patches to devices that are already in the field. Two different configurations and descriptor sets are used to support DFU functions. The Run-Time configuration co-exist with the usual functions of the device, which shall be USB Mass Storage for AT89C51SND1A. It is used to initiate DFU from the normal operating mode. The DFU configuration is used to perform the firmware update after device re-configuration and USB reset. It excludes any other function. Only the default control pipe (endpoint 0) is used to support DFU services in both configurations. The only possible value for the MaxPacketSize in the DFU configuration is 32 bytes, which is the size of the FIFO implemented for endpoint 0. 74 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Description The USB device controller provides the hardware that the AT8xC51SND1A needs to interface a USB link to a data flow stored in a double port memory. It requires a 48 MHz reference clock provided by the clock controller as detailed in Section "Clock Controller", page 75. This clock is used to generate a 12 MHz Full Speed bit clock from the received USB differential data flow and to transmit data according to full speed USB device tolerance. Clock recovery is done by a Digital Phase Locked Loop (DPLL) block. The Serial Interface Engine (SIE) block performs NRZI encoding and decoding, bit stuffing, CRC generation and checking, and the serial-parallel data conversion. The Universal Function Interface (UFI) controls the interface between the data flow and the Dual Port Ram, but also the interface with the C51 core itself. Figure 36. USB Device Controller Block Diagram USB CLOCK 48 MHz D+ 12 MHz DPLL USB Buffer D- UFI To/From C51 Core SIE Clock Controller The USB controller clock is generated by division of the PLL clock. The division factor is given by USBCD1:0 bits in USBCLK register (see Table 87). Figure 37 shows the USB controller clock generator and its calculation formula. The USB controller clock frequency must always be 48 MHz. Figure 37. USB Clock Generator and Symbol USBCLK PLL CLOCK USBCD1:0 48 MHz USB Clock PL Lclk USBclk = -------------------------------USBCD + 1 USB CLOCK USB Clock Symbol 75 4109C-8051-03/02 Serial Interface Engine (SIE) The SIE performs the following functions: * NRZI data encoding and decoding. * Bit stuffing and unstuffing. * CRC generation and checking. * ACKs and NACKs automatic generation. * TOKEN type identifying. * Address checking. * Clock recovery (using DPLL). Figure 38. SIE Block Diagram End of Packet Detector SYNC Detector Start of Packet Detector NRZI ` NRZ Bit Unstuffing Packet Bit Counter PID Decoder Address Decoder Serial to Parallel Converter D+ DUSB 48 MHz CLOCK Clock Recover 8 Data Out SysClk (12 MHz) CRC5 & CRC16 Generator/Check USB Pattern Generator Parallel to Serial Converter Bit Stuffing NRZI Converter CRC16 Generator Function Interface Unit (UFI) 8 Data In The Function Interface Unit provides the interface between the AT8xC51SND1A and the SIE. It manages transactions at the packet level with minimal intervention from the device firmware, which reads and writes the endpoint FIFOs. Figure 40 shows typical USB IN and OUT transactions reporting the split in the hardware (UFI) and software (C51) load. 76 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Figure 39. UFI Block Diagram Transfer Control FSM 12 MHz DPLL Asynchronous Information USBCON USBADDR USBINT USBIEN UEPNUM UEPCONX UEPSTAX UEPRST UEPINT UEPIEN UEPDATX UBYCTX UFNUMH UFNUML To/From C51 Core Endpoint 3 Endpoint 2 Endpoint Control USB side To/From SIE Endpoint Control C51 side Endpoint 1 Endpoint 0 Figure 40. USB Typical Transaction Load OUT Transactions: HOST UFI C51 OUT DATA0 (n bytes) OUT ACK DATA1 C51 interrupt OUT DATA1 NACK ACK Endpoint FIFO read (n bytes) IN Transactions: HOST UFI C51 IN IN NACK IN DATA1 Endpoint FIFO write ACK DATA1 C51 interrupt Endpoint FIFO write USB Interrupt System As shown in Figure 41, the USB controller of the AT8xC51SND1A handles sixteen interrupt sources. These sources are separated in two groups: the endpoints interrupts and the controller interrupts, combined together to appear as single interrupt source for the C51 core. The USB interrupt is enabled by setting the EUSB bit in IEN1. Controller Interrupt Sources There are four controller interrupt sources which can be enabled separately in USBIEN: * SPINT: Suspend Interrupt Flag. This flag triggers an interrupt when a USB Suspend (Idle bus for three frame periods: a J state for 3 ms) is detected. * SOFINT: Start Of Frame Interrupt Flag. This flag triggers an interrupt when a USB start of frame packet has been received. * EORINT: End Of Reset Interrupt Flag. This flag triggers an interrupt when a End Of Reset has been detected by the USB controller. * WUPCPU: Wake Up CPU Interrupt Flag. This flag triggers an interrupt when the USB controller is in SUSPEND state and is re-activated by a non-idle signal from USB line. 77 4109C-8051-03/02 Endpoint Interrupt Sources Each endpoint supports four interrupt sources reported in UEPSTAX and combined together to appear as a single endpoint interrupt source in UEPINT. Each endpoint interrupt can be enabled separately in UEPIEN. * TXCMP: Transmitted In Data Interrupt Flag. This flag triggers an interrupt after an IN packet has been transmitted for Isochronous endpoints or after it has been accepted (ACK'ed) by the host for Control, Bulk and Interrupt endpoints. * RXOUT: Received Out Data Interrupt Flag. This flag triggers an interrupt after a new packet has been received. * RXSETUP: Receive Setup Interrupt Flag. This flag triggers an interrupt when a valid SETUP packet has been received from the host. * STLCRC: Stall Sent Interrupt Flag/CRC Error Interrupt Flag. This flag triggers an interrupt after a STALL handshake has been sent on the bus, for Control, Bulk and Interrupt endpoints. This flag triggers an interrupt when the last data received is corrupted for Isochronous endpoints. Figure 41. USB Interrupt Control Block Diagram Endpoint x (x = 0.3) TXCMP UEPSTAX.0 RXOUT UEPSTAX.1 EPxINT UEPINT.x RXSETUP EPxIE UEPSTAX.2 UEPIEN.x STLCRC UEPSTAX.3 USB interrupt WUPCPU USBINT.5 EWUPCPU EUSB USBIEN.5 IEN1.6 EORINT USBINT.4 EEORINT USBIEN.4 SOFINT USBINT.3 ESOFINT USBIEN.3 SPINT USBINT.0 ESPINT USBIEN.0 78 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Registers Table 73. USBCON Register USBCON (S:BCh) - USB Global Control Register 7 6 5 4 3 2 1 0 USBE SUSPCLK SDRMWUP - UPRSM RMWUPE CONFG FADDEN Bit Number Bit Mnemonic Description 7 USBE 6 SUSPCLK 5 Suspend USB Clock Bit Set to disable the 48 MHz clock input (Resume Detection is still active). Clear to enable the 48 MHz clock input. Send Remote Wake-Up Bit Set to force an external interrupt on the USB controller for Remote Wake UP purpose. SDRMWUP An upstream resume is send only if the bit RMWUPE is set, all USB clocks are enabled AND the USB bus was in SUSPEND state for at least 5 ms. See UPRSM below. Cleared by software. 4 - 3 UPRSM 2 USB Enable Bit Set to enable the USB controller. Clear to disable and reset the USB controller. RMWUPE Reserved The value read from this bit is always 0. Do not set this bit. Upstream Resume Bit (read only) Set by hardware when SDRMWUP has been set and if RMWUPE is enabled. Cleared by hardware after the upstream resume has been sent. Remote Wake-Up Enable Bit Set to enabled request an upstream resume signaling to the host. Clear after the upstream resume has been indicated by RSMINPR. Note: Do not set this bit if the host has not set the DEVICE_REMOTE_WAKEUP feature for the device. 1 0 CONFG Configuration Bit Set after a SET_CONFIGURATION request with a non-zero value has been correctly processed. Clear by software when a SET_CONFIGURATION request with a zero value is received. Cleared by hardware on hardware reset or when an USB reset is detected on the bus. FADDEN Function Address Enable Bit Set by the device firmware after a successful status phase of a SET_ADDRESS transaction. It shall not be cleared afterwards by the device firmware. Cleared by hardware on hardware reset or when an USB reset is received. When this bit is cleared, the default function address is used (0). Reset Value = 0000 0000b 79 4109C-8051-03/02 Table 74. USBADDR Register USBADDR (S:C6h) - USB Address Register 7 6 5 4 3 2 1 0 FEN UADD6 UADD5 UADD4 UADD3 UADD2 UADD1 UADD0 Bit Number Bit Mnemonic Description 7 6-0 Function Enable Bit Set to enable the function. The device firmware shall set this bit after it has received a USB reset and participate in the following configuration process with the default address (FEN is reset to 0). Cleared by hardware at power-up, should not be cleared by the device firmware once set. FEN UADD6:0 USB Address Bits This field contains the default address (0) after power-up or USB bus reset. It shall be written with the value set by a SET_ADDRESS request received by the device firmware. Reset Value = 0000 0000b Table 75. USBINT Register USBINT (S:BDh) - USB Global Interrupt Register 7 6 5 4 3 2 1 0 - - WUPCPU EORINT SOFINT - - SPINT Bit Bit Number Mnemonic Description 7-6 5 - Reserved The value read from these bits is always 0. Do not set these bits. Wake Up CPU Interrupt Flag Set by hardware when the USB controller is in SUSPEND state and is re-activated WUPCPU by a non-idle signal from USB line (not by an upstream resume). This triggers a USB interrupt when EWUPCPU is set in the USBIEN. Cleared by software after re-enabling all USB clocks. 4 EORINT End of Reset Interrupt Flag Set by hardware when a End of Reset has been detected by the USB controller. This triggers a USB interrupt when EEORINT is set in USBIEN. Cleared by software. 3 SOFINT Start of Frame Interrupt Flag Set by hardware when an USB Start of Frame packet (SOF) has been properly received. This triggers a USB interrupt when ESOFINT is set in USBIEN. Cleared by software. 2-1 - 0 SPINT Reserved The value read from these bits is always 0. Do not set these bits. Suspend Interrupt Flag Set by hardware when a USB Suspend (Idle bus for three frame periods: a J state for 3 ms) is detected. This triggers a USB interrupt when ESPINT is set in USBIEN. Cleared by software. Reset Value = 0000 0000b 80 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 76. USBIEN Register USBIEN (S:BEh) - USB Global Interrupt Enable Register 7 6 5 4 3 2 1 0 - - EWUPCPU EEORINT ESOFINT - - ESPINT Bit Number Bit Mnemonic Description 7-6 - 5 Reserved The value read from these bits is always 0. Do not set these bits. Wake Up CPU Interrupt Enable Bit EWUPCPU Set to enable the Wake Up CPU interrupt. Clear to disable the Wake Up CPU interrupt. 4 EEOFINT End Of Reset Interrupt Enable Bit Set to enable the End Of Reset interrupt. This bit is set after reset. Clear to disable End Of Reset interrupt. 3 ESOFINT Start Of Frame Interrupt Enable Bit Set to enable the SOF interrupt. Clear to disable the SOF interrupt. 2-1 - 0 ESPINT Reserved The value read from these bits is always 0. Do not set these bits. Suspend Interrupt Enable Bit Set to enable Suspend interrupt. Clear to disable Suspend interrupt. Reset Value = 0001 0000b Table 77. UEPNUM Register UEPNUM (S:C7h) - USB Endpoint Number 7 6 5 4 3 2 1 0 - - - - - - EPNUM1 EPNUM0 Bit Number 7-2 1-0 Bit Mnemonic Description - Reserved The value read from these bits is always 0. Do not set these bits. Endpoint Number Bits EPNUM1: Set this field with the number of the endpoint which shall be accessed when 0 reading or writing to registers UEPSTAX, UEPDATX, UBYCTLX or UEPCONX. Reset Value = 0000 0000b 81 4109C-8051-03/02 Table 78. UEPCONX Register UEPCONX (S:D4h) - USB Endpoint X Control Register (X = EPNUM set in UEPNUM) 7 6 5 4 3 2 1 0 EPEN - - - DTGL EPDIR EPTYPE1 EPTYPE0 Bit Number Bit Mnemonic Description 7 EPEN 6-4 - Endpoint Enable Bit Set to enable the endpoint according to the device configuration. Endpoint 0 shall always be enabled after a hardware or USB bus reset and participate in the device configuration. Clear to disable the endpoint according to the device configuration. Reserved The value read from this bit is always 0. Do not set this bit. Data Toggle Status Bit (Read-only) Set by hardware when a DATA1 packet is received. Cleared by hardware when a DATA0 packet is received. 3 DTGL 2 EPDIR 1-0 Note: When a new data packet is received without DTGL toggling from 1 to 0 or 0 to 1, a packet may have been lost. When this occurs for a Bulk endpoint, the device firmware shall consider the host has retried transmitting a properly received packet because the host has not received a valid ACK, then the firmware shall discard the new packet (N.B. The endpoint resets to DATA0 only upon configuration). For interrupt endpoints, data toggling is managed as for Bulk endpoints when used. For Control endpoints, each SETUP transaction starts with a DATA0 and data toggling is then used as for Bulk endpoints until the end of the Data stage (for a control write transfer); the Status stage completes the data transfer with a DATA1 (for a control read transfer). For Isochronous endpoints, the device firmware shall retrieve every new data packet and may ignore this bit. Endpoint Direction Bit Set to configure IN direction for Bulk, Interrupt and Isochronous endpoints. Clear to configure OUT direction for Bulk, Interrupt and Isochronous endpoints. This bit has no effect for Control endpoints. Endpoint Type Bits Set this field according to the endpoint configuration (Endpoint 0 shall always be configured as Control): EPTYPE1: 00Control endpoint 0 01Isochronous endpoint 10Bulk endpoint 11Interrupt endpoint Reset Value = 0000 0000b 82 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 79. UEPSTAX Register UEPSTAX (Soh) - USB Endpoint X Status and Control Register (X = EPNUM set in UEPNUM) 7 6 5 4 3 2 1 0 DIR - STALLRQ TXRDY STLCRC RXSETUP RXOUT TXCMP Bit Bit Number Mnemonic Description 7 DIR 6 - 5 STALLRQ 4 3 2 1 0 Control Endpoint Direction Bit This bit is relevant only if the endpoint is configured in Control type. Set for the data stage. Clear otherwise. Note: This bit shall be configured on RXSETUP interrupt before any other bit is changed. This also determines the status phase (IN for a control write and OUT for a control read). This bit shall be cleared for status stage of a Control Out transaction. Reserved The value read from this bits is always 0. Do not set this bit. Stall Handshake Request Bit Set to send a STALL answer to the host for the next handshake.Clear otherwise. TXRDY TX Packet Ready Control Bit Set after a packet has been written into the endpoint FIFO for IN data transfers. Data shall be written into the endpoint FIFO only after this bit has been cleared. Set this bit without writing data to the endpoint FIFO to send a Zero Length Packet, which is generally recommended and may be required to terminate a transfer when the length of the last data packet is equal to MaxPacketSize (e.g. for control read transfers). Cleared by hardware, as soon as the packet has been sent for Isochronous endpoints, or after the host has acknowledged the packet for Control, Bulk and Interrupt endpoints. STLCRC Stall Sent Interrupt Flag/CRC Error Interrupt Flag For Control, Bulk and Interrupt Endpoints: Set by hardware after a STALL handshake has been sent as requested by STALLRQ. Then, the endpoint interrupt is triggered if enabled in UEPIEN. Cleared by hardware when a SETUP packet is received (see RXSETUP). For Isochronous Endpoints: Set by hardware if the last data received is corrupted (CRC error on data). Then, the endpoint interrupt is triggered if enabled in UEPIEN. Cleared by hardware when a non corrupted data is received. Received SETUP Interrupt Flag Set by hardware when a valid SETUP packet has been received from the host. RXSETUP Then, all the other bits of the register are cleared by hardware and the endpoint interrupt is triggered if enabled in UEPIEN. Clear by software after reading the SETUP data from the endpoint FIFO. RXOUT Received OUT Data Interrupt Flag Set by hardware after an OUT packet has been received. Then, the endpoint interrupt is triggered if enabled in UEPIEN and all the following OUT packets to the endpoint are rejected (NACK'ed) until this bit is cleared. However, for Control endpoints, an early SETUP transaction may overwrite the content of the endpoint FIFO, even if its Data packet is received while this bit is set. Clear by software after reading the OUT data from the endpoint FIFO. TXCMP Transmitted IN Data Complete Interrupt Flag Set by hardware after an IN packet has been transmitted for Isochronous endpoints and after it has been accepted (ACK'ed) by the host for Control, Bulk and Interrupt endpoints. Then, the endpoint interrupt is triggered if enabled in UEPIEN. Clear by software before setting again TXRDY. Reset Value = 0000 0000b 83 4109C-8051-03/02 Table 80. UEPRST Register UEPRST (S:D5h) - USB Endpoint FIFO Reset Register 7 6 5 4 3 2 1 0 - - - - EP3RST EP2RST EP1RST EP0RST Bit Number Bit Mnemonic Description Reserved The value read from these bits is always 0. Do not set these bits. 7-4 - 3 EP3RST Endpoint 3 FIFO Reset Set and clear to reset the endpoint 3 FIFO prior to any other operation, upon hardware reset or when an USB bus reset has been received. 2 EP2RST Endpoint 2 FIFO Reset Set and clear to reset the endpoint 2 FIFO prior to any other operation, upon hardware reset or when an USB bus reset has been received. 1 EP1RST Endpoint 1 FIFO Reset Set and clear to reset the endpoint 1 FIFO prior to any other operation, upon hardware reset or when an USB bus reset has been received. 0 EP0RST Endpoint 0 FIFO Reset Set and clear to reset the endpoint 0 FIFO prior to any other operation, upon hardware reset or when an USB bus reset has been received. Reset Value = 0000 0000b Table 81. UEPINT Register UEPINT (S:F8h Read-only) - USB Endpoint Interrupt Register 7 6 5 4 3 2 1 0 - - - - EP3INT EP2INT EP1INT EP0INT Bit Number 7-4 3 2 1 0 Bit Mnemonic Description - Reserved The value read from these bits is always 0. Do not set these bits. EP3INT Endpoint 3 Interrupt Flag Set by hardware when an interrupt is triggered in UEPSTAX and the endpoint 3 interrupt is enabled in UEPIEN. Must be cleared by software. EP2INT Endpoint 2 Interrupt Flag Set by hardware when an interrupt is triggered in UEPSTAX and the endpoint 2 interrupt is enabled in UEPIEN. Must be cleared by software. EP1INT Endpoint 1 Interrupt Flag Set by hardware when an interrupt is triggered in UEPSTAX and the endpoint 1 interrupt is enabled in UEPIEN. Must be cleared by software. EP0INT Endpoint 0 Interrupt Flag Set by hardware when an interrupt is triggered in UEPSTAX and the endpoint 0 interrupt is enabled in UEPIEN. Must be cleared by software. Reset Value = 0000 0000b 84 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 82. UEPIEN Register UEPIEN (S:C2h) - USB Endpoint Interrupt Enable Register 7 6 5 4 3 2 1 0 - - - - EP3INTE EP2INTE EP1INTE EP0INTE Bit Number Bit Mnemonic Description Reserved The value read from these bits is always 0. Do not set these bits. 7-4 - 3 EP3INTE Endpoint 3 Interrupt Enable Bit Set to enable the interrupts for endpoint 3. Clear to disable the interrupts for endpoint 3. 2 EP2INTE Endpoint 2 Interrupt Enable Bit Set to enable the interrupts for endpoint 2. Clear this bit to disable the interrupts for endpoint 2. 1 EP1INTE Endpoint 1 Interrupt Enable Bit Set to enable the interrupts for the endpoint 1. Clear to disable the interrupts for the endpoint 1. 0 EP0INTE Endpoint 0 Interrupt Enable Bit Set to enable the interrupts for the endpoint 0. Clear to disable the interrupts for the endpoint 0. Reset Value = 0000 0000b Table 83. UEPDATX Register UEPDATX (S:CFh) - USB Endpoint X FIFO Data Register (X = EPNUM set in UEPNUM) 7 6 5 4 3 2 1 0 FDAT7 FDAT6 FDAT5 FDAT4 FDAT3 FDAT2 FDAT1 FDAT0 Bit Number 7-0 Bit Mnemonic Description FDAT7:0 Endpoint X Fifo Data Data byte to be written to Fifo or data byte to be read from the Fifo, for the Endpoint X (see EPNUM). Reset Value = XXh 85 4109C-8051-03/02 Table 84. UBYCTLX Register UBYCTX (S:E2h) - USB Endpoint X Byte Count Register (X = EPNUM set in UEPNUM) 7 6 5 4 3 2 1 0 - BYCT6 BYCT5 BYCT4 BYCT3 BYCT2 BYCT1 BYCT0 Bit Number Bit Mnemonic Description 7 - 6-0 BYCT7:0 Reserved The value read from this bits is always 0. Do not set this bit. Byte Count Byte count of a received data packet. This byte count is equal to the number of data bytes received after the Data PID. Reset Value = 0000 0000b Table 85. UFNUML Register UFNUML (S:BAh, Read-only) - USB Frame Number Low Register 7 6 5 4 3 2 1 0 FNUM7 FNUM6 FNUM5 FNUM4 FNUM3 FNUM2 FNUM1 FNUM0 Bit Number 7-0 Bit Mnemonic Description FNUM7:0 Frame Number Lower 8 bits of the 11-bit Frame Number. Reset Value = 00h 86 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 86. UFNUMH Register UFNUMH (S:BBh, Read-only) - USB Frame Number High Register 7 6 5 4 3 2 1 0 - - CRCOK CRCERR - FNUM10 FNUM9 FNUM8 Bit Number Bit Mnemonic 7-3 - 5 Description Reserved The value read from these bits is always 0. Do not set these bits. CRCOK Frame Number CRC OK Bit Set by hardware after a non corrupted Frame Number in Start of Frame Packet is received. Updated after every Start Of Frame packet reception. Note: The Start Of Frame interrupt is generated just after the PID receipt. 4 CRCERR Frame Number CRC Error Bit Set by hardware after a corrupted Frame Number in Start of Frame Packet is received. Updated after every Start Of Frame packet reception. Note: The Start Of Frame interrupt is generated just after the PID receipt. Reserved The value read from this bits is always 0. Do not set this bit. 3 - 2-0 FNUM10:8 Frame Number Upper 3 bits of the 11-bit Frame Number. It is provided in the last received SOF packet. FNUM does not change if a corrupted SOF is received. Reset Value = 00h Table 87. USBCLK Register USBCLK (S:EAh) - USB Clock Divider Register 7 6 5 4 3 2 1 0 - - - - - - USBCD1 USBCD0 Bit Number Bit Mnemonic Description 7-2 - 1-0 USBCD1:0 Reserved The value read from these bits is always 0. Do not set these bits. USB Controller Clock Divider 2-bit divider for USB controller clock generation. Reset Value = 0000 0000b 87 4109C-8051-03/02 MultiMediaCard Controller The AT8xC51SND1A implements a MultiMediaCard (MMC) controller. The MMC is used to store MP3 encoded audio files in removable flash memory cards that can be easily plugged or removed from the application. Card Concept The basic MultiMediaCard concept is based on transferring data via a minimal number of signals. Card Signals The communication signals are: * CLK: with each cycle of this signal an one bit transfer on the command and data lines is done. The frequency may vary from zero to the maximum clock frequency. * CMD: is a bidirectional command channel used for card initialization and data transfer commands. The CMD signal has two operation modes: open-drain for initialization mode and push-pull for fast command transfer. Commands are sent from the MultiMediaCard bus master to the card and responses from the cards to the host. * DAT: is a bidirectional data channel. The DAT signal operates in push-pull mode. Only one card or the host is driving this signal at a time. Card Registers Within the card interface five registers are defined: OCR, CID, CSD, RCA and DSR. These can be accessed only by corresponding commands. The 32-bit Operation Conditions Register (OCR) stores the VDD voltage profile of the card. The register is optional and can be read only. The 128-bit wide CID register carries the card identification information (Card ID) used during the card identification procedure. The 128-bit wide Card-Specific Data register (CSD) provides information on how to access the card contents. The CSD defines the data format, error correction type, maximum data access time, data transfer speed, and whether the DSR register can be used. The 16-bit Relative Card Address register (RCA) carries the card address assigned by the host during the card identification. This address is used for the addressed host-card communication after the card identification procedure. The 16-bit Driver Stage Register (DSR) can be optionally used to improve the bus performance for extended operating conditions (depending on parameters like bus length, transfer rate or number of cards). Bus Concept The MultiMediaCard bus is designed to connect either solid-state mass-storage memory or I/O-devices in a card format to multimedia applications. The bus implementation allows the coverage of application fields from low-cost systems to systems with a fast data transfer rate. It is a single master bus with a variable number of slaves. The MultiMediaCard bus master is the bus controller and each slave is either a single mass storage card (with possibly different technologies such as ROM, OTP, Flash etc.) or an I/O-card with its own controlling unit (on card) to perform the data transfer. The MultiMediaCard bus also includes power connections to supply the cards. The bus communication uses a special protocol (MultiMediaCard bus protocol) which is applicable for all devices. Therefore, the payload data transfer between the host and the cards can be bidirectional. 88 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Bus Lines The MultiMediaCard bus architecture requires all cards to be connected to the same set of lines. No card has an individual connection to the host or other devices, which reduces the connection costs of the MultiMediaCard system. The bus lines can be divided into three groups: Bus Protocol * Power supply: VSS1 and V SS2, VDD - used to supply the cards. * Data transfer: MCMD, MDAT - used for bidirectional communication. * Clock: MCLK - used to synchronize data transfer across the bus. After a power-on reset, the host must initialize the cards by a special message-based MultiMediaCard bus protocol. Each message is represented by one of the following tokens: * Command: a command is a token which starts an operation. A command is transferred serially from the host to the card on the MCMD line. * Response: a response is a token which is sent from an addressed card (or all connected cards) to the host as an answer to a previously received command. It is transferred serially on the MCMD line. * Data: data can be transferred from the card to the host or vice-versa. Data is transferred serially on the MDAT line. Card addressing is implemented using a session address assigned during the initialization phase, by the bus controller to all currently connected cards. Individual cards are identified by their CID number. This method requires that every card will have an unique CID number. To ensure uniqueness of CIDs the CID register contains 24 bits (MID and OID fields) which are defined by the MMCA. Every card manufacturers is required to apply for an unique MID (and optionally OID) number. MultiMediaCard bus data transfers are composed of these tokens. One data transfer is a bus operation. There are different types of operations. Addressed operations always contain a command and a response token. In addition, some operations have a data token, the others transfer their information directly within the command or response structure. In this case no data token is present in an operation. The bits on the MDAT and the MCMD lines are transferred synchronous to the host clock. Two types of data transfer commands are defined: * Sequential commands: These commands initiate a continuous data stream, they are terminated only when a stop command follows on the MCMD line. This mode reduces the command overhead to an absolute minimum. * Block-oriented commands: These commands send a data block succeeded by CRC bits. Both read and write operations allow either single or multiple block transmission. A multiple block transmission is terminated when a stop command follows on the MCMD line similarly to the stream read. Figure 17 to Figure 45 show the different types of operations, on these figures, grayed tokens are from host to card(s) while white tokens are from card(s) to host. Figure 17. Sequential Read Operation Stop Command MCMD Command Response MDAT Command Response Data Stream Data Transfer Operation Data Stop Operation 89 4109C-8051-03/02 Figure 42. (Multiple) Block Read Operation Stop Command MCMD Command Response MDAT Command Response Data Block CRC Data Block CRC Data Block CRC Block Read Operation Data Stop Operation Multiple Block Read Operation As shown in Figure 43 and Figure 44 the data write operation uses a simple busy signalling of the write operation duration on the data line (MDAT). Figure 43. Sequential Write Operation Stop Command MCMD Command Response Command MDAT Data Stream Response Busy Data Transfer Operation Data Stop Operation Figure 44. (Multiple) Block Write Operation Stop Command MCMD Command Response Command Data Block CRC Status Busy MDAT Response Data Block CRC Status Busy Block Write Operation Data Stop Operation Multiple Block Write Operation Figure 45. No Response and No Data Operation MCMD Command Command Response MDAT No Response Operation Command Token Format No Data Operation As shown in Figure 46, commands have a fixed code length of 48 bits. Each command token is preceded by a Start bit: a low level on MCMD line and succeeded by an End bit: a high level on MCMD line. The command content is preceded by a Transmission bit: a high level on MCMD line for a command token (host to card) and succeeded by a 7-bit CRC so that transmission errors can be detected and the operation may be repeated. Command content contains the command index and address information or parameters. Figure 46. Command Token Format 0 1 Content CRC 1 Total Length = 48 90 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 88. Command Token Format Bit Position 47 46 45:40 39:8 7:1 0 Width (bits) 1 1 6 32 7 1 Value `0' `1' - - - `1' Start bit Transmission bit Command Index Argument CRC7 End bit Description Response Token Format There are five types of response tokens (R1 to R5). As shown in Figure 18, responses have a code length of 48 bits or 136 bits. A response token is preceded by a Start bit: a low level on MCMD line and succeeded by an End bit: a high level on MCMD line. The command content is preceded by a Transmission bit: a low level on MCMD line for a response token (card to host) and succeeded (R1,R2,R4,R5) or not (R3) by a 7-bit CRC. Response content contains mirrored command and status information (R1 response), CID register or CSD register (R2 response), OCR register (R3 response), or RCA register (R4 and R5 response). Figure 18. Response Token Format R1, R4, R5 0 0 Content CRC 1 Total Length = 48 R3 0 0 Content 1 Total Length = 48 R2 0 0 Content = CID or CSD CRC 1 Total Length = 136 bits Table 89. R1 Response Format (Normal Response) Bit Position 47 46 45:40 39:8 7:1 0 Width (bits) 1 1 6 32 7 1 Value `0' `0' - - - `1' Start bit Transmission bit Command Index Card Status CRC7 End bit Description Table 90. R2 Response Format (CID and CSD registers) Bit Position 135 134 [133:128] [127:1] 0 Width (bits) 1 1 6 32 1 Value `0' `0' `111111' - `1' Start bit Transmission bit Reserved Argument End bit Description 91 4109C-8051-03/02 Table 91. R3 Response Format (OCR Register) Bit Position 47 46 [45:40] [39:8] [7:1] 0 Width (bits) 1 1 6 32 7 1 Value `0' `0' `111111' - `1111111' `1' Start bit Transmission bit Reserved OCR register Reserved End bit Description Table 92. R4 Response Format (Fast I/O) Bit Position 47 46 [45:40] [39:8] [7:1] 0 Width (bits) 1 1 6 32 7 1 Value `0' `0' `100111' - - `1' Start bit Transmission bit Command Index Argument CRC7 End bit Description Table 93. R5 Response Format Bit Position 47 46 [45:40] [39:8] [7:1] 0 Width (bits) 1 1 6 32 7 1 Value `0' `0' `101000' - - `1' Start bit Transmission bit Command Index Argument CRC7 End bit Description Data Packet Format There are two types of data packets: stream and block. As shown in Figure 19, stream data packets have an indeterminate length while block packets have a fixed length depending on the block length. Each data packet is preceded by a Start bit: a low level on MCMD line and succeeded by an End bit: a high level on MCMD line. Due to the fact that there is no predefined end in stream packets, CRC protection is not included in this case. The CRC protection algorithm for block data is a 16-bit CCITT polynomial. Figure 19. Data Token Format Sequential Data 0 Block Data 0 Content Content 1 CRC 1 Block Length Clock Control 92 The MMC bus clock signal can be used by the host to turn the cards into energy saving mode or to control the data flow (to avoid under-run or over-run conditions) on the bus. The host is allowed to lower the clock frequency or shut it down. There are a few restrictions the host must follow: * The bus frequency can be changed at any time (under the restrictions of maximum data transfer frequency, defined by the cards, and the identification frequency defined by the specification document). * It is an obvious requirement that the clock must be running for the card to output data or response tokens. After the last MultiMediaCard bus transaction, the host is AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A required, to provide 8 (eight) clock cycles for the card to complete the operation before shutting down the clock. Following is a list of the various bus transactions: Description * A command with no response. 8 clocks after the host command End bit. * A command with response. 8 clocks after the card command End bit. * A read data transaction. 8 clocks after the End bit of the last data block. * A write data transaction. 8 clocks after the CRC status token. * The host is allowed to shut down the clock of a "busy" card. The card will complete the programming operation regardless of the host clock. However, the host must provide a clock edge for the card to turn off its busy signal. Without a clock edge the card (unless previously disconnected by a deselect command-CMD7) will force the MDAT line down, forever. The MMC controller interfaces to the C51 core through the following eight special function registers: MMCON0, MMCON1, MMCON2, the three MMC control registers (see Figure 95 to Figure ); MMSTA, the MMC status register (see Figure 98); MMINT, the MMC interrupt register (see Figure ); MMMSK, the MMC interrupt mask register (see Figure 100); MMCMD, the MMC command register (see Figure 101); MMDAT, the MMC data register (see Figure ); and MMCLK, the MMC clock register (see Figure 103). As shown in Figure 47, the MMC controller is divided in four blocks: the clock generator that handles the MCLK (formally the MMC CLK) output to the card, the command line controller that handles the MCMD (formally the MMC CMD) line traffic to or from the card, the data line controller that handles the MDAT (formally the MMC DAT) line traffic to or from the card, and the interrupt controller that handles the MMC controller interrupt sources. These blocks are detailed in the following sections. Figure 47. MMC Controller Block Diagram MCLK OSC CLOCK Clock Generator Command Line Controller MCMD Interrupt Controller Internal Bus Clock Generator Data Line Controller 8 MMC Interrupt Request MDAT The MMC clock is generated by division of the oscillator clock (FOSC) issued from the Clock Controller block as detailed in Section "Oscillator", page 4. The division factor is given by MMCD7:0 bits in MMCLK register. Figure 48 shows the MMC clock generator and its output clock calculation formula. 93 4109C-8051-03/02 Figure 48. MMC Clock Generator and Symbol OSC CLOCK Controller Clock OSCclk MMCclk = ----------------------------MMCD + 1 MMCLK MMCEN MMCD7:0 MMCON2.7 MMC Clock MMC CLOCK MMC Clock Symbol As soon as MMCEN bit in MMCON2 is set, the MMC controller receives its system clock. The MMC command and data clock is generated on MCLK output and sent to the command line and data line controllers. Figure 49 shows the MMC controller configuration flow. As exposed in Section , MMCD7:0 bits can be used to dynamically increase or reduce the MMC clock. Figure 49. Configuration Flow MMC Controller Configuration Configure MMC Clock MMCLK = XXh MMCEN = 1 FLOWC = 0 94 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Command Line Controller As shown in Figure 50, the command line controller is divided in two channels: the command transmitter channel that handles the command transmission to the card through the MCMD line and the command receiver channel that handles the response reception from the card through the MCMD line. These channels are detailed in the following sections. Figure 50. Command Line Controller Block Diagram TX Pointer 5-byte FIFO CTPTR MMCMD Write MMCON0.4 Data Converter // -> Serial CRC7 Generator TX COMMAND Line Finished State Machine CFLCK MMINT.5 EOCI MMSTA.0 CMDEN RX Pointer CRPTR MMCON0.5 MCMD MMCON1.0 Command Transmitter 17-byte FIFO Data Converter Serial -> // MMSTA.2 MMSTA.1 CRC7S RESPFS CRC7 and Format Checker MMCMD Read RX COMMAND Line Finished State Machine RESPEN EORI CRCDIS MMCON1.1 MMCON0.1 MMCON0.0 Command Receiver Command Transmitter RFMT MMINT.6 For sending a command to the card, user must load the command index (1 byte) and argument (4 bytes) in the command transmit FIFO using the MMCMD register. Before starting transmission by setting and clearing the CMDEN bit in MMCON1 register, user must first configure: * RESPEN bit in MMCON1 register to indicate whether a response is expected or not. * RFMT bit in MMCON0 register to indicate the response size expected. * CRCDIS bit in MMCON0 register to indicate whether the CRC7 included in the response will be computed or not. In order to avoid CRC error, CRCDIS may be set for response that do not include CRC7. Figure 20 summarizes the command transmission flow. As soon as command transmission is enabled, the CFLCK flag in MMSTA is set indicating that write to the FIFO is locked. This mechanism is implemented to avoid command overrun. The end of the command transmission is signalled to you by the EOCI flag in MMINT register becoming set. This flag may generate an MMC interrupt request as detailed in Section "Interrupt", page 103. The end of the command transmission also resets the CFLCK flag. 95 4109C-8051-03/02 User may abort command loading by setting and clearing the CTPTR bit in MMCON0 register which resets the write pointer to the transmit FIFO. Figure 20. Command Transmission Flow Command Transmission Configure Response RESPEN = X RFMT = X CRCDIS = X Load Command in Buffer MMCMD = index MMCMD = argument Transmit Command CMDEN = 1 CMDEN = 0 Command Receiver The end of the response reception is signalled to you by the EORI flag in MMINT register. This flag may generate an MMC interrupt request as detailed in Section "Interrupt", page 103. When this flag is set, two other flags in MMSTA register: RESPFS and CRC7S give a status on the response received. RESPFS indicates if the response format is correct or not: the size is the one expected (48 bits or 136 bits) and a valid End bit has been received, and CRC7S indicates if the CRC7 computation is correct or not. These Flags are cleared when a command is sent to the card and updated when the response has been received. User may abort response reading by setting and clearing the CRPTR bit in MMCON0 register which resets the read pointer to the receive FIFO. According to the MMC specification delay between a command and a response (formally NCR parameter) can not exceed 64 MMC clock periods. To avoid any locking of the MMC controller when card does not send its response (e.g. physically removed from the bus), user must launch a time-out period to exit from such situation. In case of timeout user may reset the command controller and its internal state machine by setting and clearing the CCR bit in MMCON2 register. This time-out may be disarmed when receiving the response. 96 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Data Line Controller The data line controller is based on a 16-byte FIFO used both by the data transmitter channel and by the data receiver channel. Figure 51. Data Line Controller Block Diagram MMINT.0 MMINT.2 MMSTA.3 MMSTA.4 F1EI F1FI DATFS CRC16S CRC16 and Format Checker Data Converter Serial -> // 8-byte TX Pointer FIFO 1 DTPTR MMCON0.6 RX Pointer DRPTR MMCON0.7 16-byte FIFO MMDAT MCBI CBUSY MMINT.1 MMSTA.5 MDAT Data Converter // -> Serial CRC16 Generator 8-byte MMINT.4 DATA Line Finished State Machine FIFO 2 F2EI F2FI MMINT.1 MMINT.3 DFMT MBLOCK DATEN MMCON0.2 MMCON0.3 MMCON1.2 DATDIR EOFI BLEN3:0 MMCON1.3 MMCON1.7:4 FIFO Implementation The 16-byte FIFO is based on a dual 8-byte FIFOs managed using two pointers and four flags indicating the status full and empty of each FIFO. Pointers are not accessible to user but can be reset at any time by setting and clearing DRPTR and DTPTR bits in MMCON0 register. Resetting the pointers is equivalent to abort the writing or reading of data. F1EI and F2EI flags in MMINT register signal when set that respectively FIFO1 and FIFO2 are empty. F1FI and F2FI flags in MMINT register signal when set that respectively FIFO1 and FIFO2 are full. These flags may generate an MMC interrupt request as detailed in Section . Data Configuration Before sending or receiving any data, the data line controller must be configured according to the type of the data transfer considered. This is achieved using the Data Format bit: DFMT in MMCON0 register. Clearing DFMT bit enables the data stream format while setting DFMT bit enables the data block format. In data block format, user must also configure the single or multi-block mode by clearing or setting the MBLOCK bit in MMCON0 register and the block length using BLEN3:0 bits in MMCON1 according to Table 94. Figure 21 summarizes the data modes configuration flows. Table 94. Block Length Programming BLEN3:0 BLEN = 0000 to 1011 > 1011 Block Length (Byte) Length = 2 BLEN: 1 to 2048 Reserved: do not program BLEN3:0 > 1011 97 4109C-8051-03/02 Figure 21. Data Controller Configuration Flows Data Stream Configuration Data Single Block Configuration Data Multi-Block Configuration Configure Format DFMT = 0 Configure Format DFMT = 1 MBLOCK = 0 BLEN3:0 = XXXXb Configure Format DFMT = 1 MBLOCK = 1 BLEN3:0 = XXXXb Data Transmitter Configuration For transmitting data to the card user must first configure the data controller in transmission mode by setting the DATDIR bit in MMCON1 register. Figure 52 summarizes the data stream transmission flows in both polling and interrupt modes while Figure 53 summarizes the data block transmission flows in both polling and interrupt modes, these flows assume that block length is greater than 16 data. Data Loading Data is loaded in the FIFO by writing to MMDAT register. Number of data loaded may vary from 1 to 16 bytes. Then if necessary (more than 16 bytes to send) user must wait that one FIFO becomes empty (F1EI or F2EI set) before loading 8 new data. Data Transmission Transmission is enabled by setting and clearing DATEN bit in MMCON1 register. Data is transmitted immediately if the response has already been received, or is delayed after the response reception if its status is correct. In both cases transmission is delayed if a card sends a busy state on the data line until the end of this busy condition. According to the MMC specification, the data transfer from the host to the card may not start sooner than 2 MMC clock periods after the card response was received (formally N WR parameter). To address all card types, this delay can be programmed using DATD1:0 bits in MMCON2 register from 2 MMC clock periods when DATD1:0 bits are cleared to 8 MMC clock periods when DATD2:0 bits are set, by step of 2 MMC clock periods. End of Transmission The end of a data frame (block or stream) transmission is signalled to you by the EOFI flag in MMINT register. This flag may generate an MMC interrupt request as detailed in Section "Interrupt", page 103. In data stream mode, EOFI flag is set, after reception of the End bit. This assumes user has previously sent the STOP command to the card, which is the only way to stop stream transfer. In data block mode, EOFI flag is set, after reception of the CRC status token (see Figure 44). Two other flags in MMSTA register: DATFS and CRC16S report a status on the frame sent. DATFS indicates if the CRC status token format is correct or not, and CRC16S indicates if the card has found the CRC16 of the block correct or not. Busy Status 98 As shown in Figure 44 the card uses a busy token during a block write operation. This busy status is reported to you by the CBUSY flag in MMSTA register and by the MCBI flag in MMINT which is set every time CBUSY toggles, i.e. when the card enters and exits its busy state. This flag may generate an MMC interrupt request as detailed in Section "Interrupt", page 103. AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Figure 52. Data Stream Transmission Flows Data Stream Transmission Data Stream Initialization Data Stream Transmission ISR FIFOs Filling write 16 data to MMDAT FIFOs Filling write 16 data to MMDAT Start Transmission DATEN = 1 DATEN = 0 Unmask FIFOs Empty F1EM = 0 F2EM = 0 FIFO Empty? F1EI or F2EI = 1? Start Transmission DATEN = 1 DATEN = 0 FIFO Empty? F1EI or F2EI = 1? FIFO Filling write 8 data to MMDAT FIFO Filling write 8 data to MMDAT Mask FIFOs Empty F1EM = 1 F2EM = 1 No More Data To Send? Send STOP Command No More Data To Send? Send STOP Command b. Interrupt mode a. Polling mode 99 4109C-8051-03/02 Figure 53. Data Block Transmission Flows Data Block Transmission Data Block Initialization FIFOs Filling write 16 data to MMDAT FIFOs Filling write 16 data to MMDAT Start Transmission DATEN = 1 DATEN = 0 Unmask FIFOs Empty F1EM = 0 F2EM = 0 FIFO Empty? F1EI or F2EI = 1? Start Transmission DATEN = 1 DATEN = 0 FIFO Filling write 8 data to MMDAT No More Data To Send? Data Block Transmission ISR FIFO Empty? F1EI or F2EI = 1? FIFO Filling write 8 data to MMDAT No More Data To Send? Mask FIFOs Empty F1EM = 1 F2EM = 1 b. Interrupt mode a. Polling mode Data Receiver Configuration To receive data from the card you must first configure the data controller in reception mode by clearing the DATDIR bit in MMCON1 register. Figure 54 summarizes the data stream reception flows in both polling and interrupt modes while Figure 55 summarizes the data block reception flows in both polling and interrupt modes, these flows assume that block length is greater than 16 bytes. Data Reception The end of a data frame (block or stream) reception is signalled to you by the EOFI flag in MMINT register. This flag may generate an MMC interrupt request as detailed in Section "Interrupt", page 103. When this flag is set, two other flags in MMSTA register: DATFS and CRC16S give a status on the frame received. DATFS indicates if the frame format is correct or not: a valid End bit has been received, and CRC16S indicates if the CRC16 computation is correct or not. In case of data stream CRC16S has no meaning and stays cleared. According to the MMC specification data transmission from the card starts after the access time delay (formally NAC parameter) beginning from the End bit of the read command. To avoid any locking of the MMC controller when card does not send its data (e.g. physically removed from the bus), you must launch a time-out period to exit from such situation. In case of time-out you may reset the data controller and its internal state machine by setting and clearing the DCR bit in MMCON2 register. 100 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A This time-out may be disarmed after receiving 8 data (F1FI flag set) or after receiving end of frame (EOFI flag set) in case of block length less than 8 data (1, 2 or 4). Data Reading Data is read from the FIFO by reading to MMDAT register. Each time one FIFO becomes full (F1FI or F2FI set), user is requested to flush this FIFO by reading 8 data. Figure 54. Data Stream Reception Flows Data Stream Reception Data Stream Initialization Data Stream Reception ISR FIFO Full? F1FI or F2FI = 1? Unmask FIFOs Full F1FM = 0 F2FM = 0 FIFO Full? F1FI or F2FI = 1? FIFO Reading read 8 data from MMDAT FIFO Reading read 8 data from MMDAT No More Data To Receive? No More Data To Receive? Send STOP Command Mask FIFOs Full F1FM = 1 F2FM = 1 a. Polling mode Send STOP Command b. Interrupt mode 101 4109C-8051-03/02 Figure 55. Data Block Reception Flows Data Block Reception Data Block Initialization Data Block Reception ISR Start Transmission DATEN = 1 DATEN = 0 Unmask FIFOs Full F1FM = 0 F2FM = 0 FIFO Full? F1EI or F2EI = 1? FIFO Full? F1EI or F2EI = 1? Start Transmission DATEN = 1 DATEN = 0 FIFO Reading read 8 data from MMDAT No More Data To Receive? FIFO Reading read 8 data from MMDAT Mask FIFOs Full F1FM = 1 F2FM = 1 No More Data To Receive? a. Polling mode Flow Control b. Interrupt mode To allow transfer at high speed without taking care of CPU oscillator frequency, the FLOWC bit in MMCON2 allows control of the data flow in both transmission and reception. During transmission, setting the FLOWC bit has the following effects: * MMCLK is stopped when both FIFOs become empty: F1EI and F2EI set. * MMCLK is restarted when one of the FIFOs becomes full: F1EI or F2EI cleared. During reception, setting the FLOWC bit has the following effects: * MMCLK is stopped when both FIFOs become full: F1FI and F2FI set. * MMCLK is restarted when one of the FIFOs becomes empty: F1FI or F2FI cleared. As soon as the clock is stopped, the MMC bus is frozen and remains in its state until the clock is restored by writing or reading data in MMDAT. 102 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Interrupt Description As shown in Figure 56, the MMC controller implements eight interrupt sources reported in MCBI, EORI, EOCI, EOFI, F2FI, F1FI, and F2EI flags in MMCINT register. These flags are detailed in the previous sections. All these sources are maskable separately using MCBM, EORM, EOCM, EOFM, F2FM, F1FM, and F2EM mask bits respectively in MMMSK register. The interrupt request is generated each time an unmasked flag is set, and the global MMC controller interrupt enable bit is set (EMMC in IEN1 register). Reading the MMINT register automatically clears the interrupt flags (acknowledgment). This implies that register content must be saved and tested interrupt flag by interrupt flag to be sure not to forget any interrupts. Figure 56. MMC Controller Interrupt System MCBI MMINT.7 MCBM MMMSK.7 EORI MMINT.6 EORM EOCI MMMSK.6 MMINT.5 EOCM MMMSK.5 EOFI MMINT.4 MMC Interface Interrupt Request EOFM F2FI MMMSK.4 EMMC MMINT.3 F2FM IEN1.0 MMMSK.3 F1FI MMINT.2 F1FM F2EI MMMSK.2 MMINT.1 F2EM MMMSK.1 F1EI MMINT.0 F1EM MMMSK.0 103 4109C-8051-03/02 Registers Table 95. MMCON0 Register MMCON0 (S:E4h) - MMC Control Register 0 7 6 5 4 3 2 1 0 DRPTR DTPTR CRPTR CTPTR MBLOCK DFMT RFMT CRCDIS Bit Number Bit Mnemonic Description 7 DRPTR Data Receive Pointer Reset Bit Set to reset the read pointer of the data FIFO. Clear to release the read pointer of the data FIFO. 6 DTPTR Data Transmit Pointer Reset Bit Set to reset the write pointer of the data FIFO. Clear to release the write pointer of the data FIFO. 5 CRPTR Command Receive Pointer Reset Bit Set to reset the read pointer of the receive command FIFO. Clear to release the read pointer of the receive command FIFO. 4 CTPTR Command Transmit Pointer Reset Bit Set to reset the write pointer of the transmit command FIFO. Clear to release the read pointer of the transmit command FIFO. 3 MBLOCK 2 DFMT Data Format Bit Set to select the block-oriented data format. Clear to select the stream data format. 1 RFMT Response Format Bit Set to select the 48-bit response format. Clear to select the 136-bit response format. 0 CRCDIS Multi-block Enable Bit Set to select multi-block data format. Clear to select single block data format. CRC7 Disable Bit Set to disable the CRC7 computation when receiving a response. Clear to enable the CRC7 computation when receiving a response. Reset Value = 0000 0000b 104 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 96. MMCON1 Register MMCON1 (S:E5h) - MMC Control Register 1 7 6 5 4 3 2 1 0 BLEN3 BLEN2 BLEN1 BLEN0 DATDIR DATEN RESPEN CMDEN Bit Number Bit Mnemonic Description 7-4 BLEN3:0 Block Length Bits Refer to Table 94 for bits description. Do not program value > 1011b 3 DATDIR Data Direction Bit Set to select data transfer from host to card (write mode). Clear to select data transfer from card to host (read mode). 2 DATEN Data Transmission Enable Bit Set and clear to enable data transmission immediately or after response has been received. 1 RESPEN Response Enable Bit Set and clear to enable the reception of a response following a command transmission. 0 CMDEN Command Transmission Enable Bit Set and clear to enable transmission of the command FIFO to the card. Reset Value = 0000 0000b Table 97. MMCON2 Register MMCON2 (S:E6h) - MMC Control Register 2 7 6 5 4 3 2 1 0 MMCEN DCR CCR - - DATD1 DATD0 FLOWC Bit Number Bit Mnemonic Description MMC Clock Enable Bit Set to enable the MCLK clocks and activate the MMC controller. Clear to disable the MMC clocks and freeze the MMC controller. 7 MMCEN 6 DCR Data Controller Reset Bit Set and clear to reset the data line controller in case of transfer abort. 5 CCR Command Controller Reset Bit Set and clear to reset the command line controller in case of transfer abort. 4-3 - 2-1 DATD1:0 Data Transmission Delay Bits Used to delay the data transmission after a response from 2 MMC clock periods (all bits cleared) to 8 MMC clock periods (all bits set) by step of 2 MMC clock periods. 0 FLOWC MMC Flow Control Bit Set to enable the flow control during data transfers. Clear to disable the flow control during data transfers. Reserved The value read from these bits is always 0. Do not set these bits. Reset Value = 0000 0000b 105 4109C-8051-03/02 Table 98. MMSTA Register MMSTA (S:DEh Read Only) - MMC Control and Status Register 7 6 5 4 3 2 1 0 - - CBUSY CRC16S DATFS CRC7S RESPFS CFLCK Bit Number Bit Mnemonic Description Reserved The value read from these bits is always 0. Do not set these bits. 7-6 - 5 CBUSY Card Busy Flag Set by hardware when the card sends a busy state on the data line. Cleared by hardware when the card no more sends a busy state on the data line. CRC16S CRC16 Status Bit Transmission mode Set by hardware when the token response reports a good CRC. Cleared by hardware when the token response reports a bad CRC. Reception mode Set by hardware when the CRC16 received in the data block is correct. Cleared by hardware when the CRC16 received in the data block is not correct. 4 3 2 DATFS CRC7S Data Format Status Bit Transmission mode Set by hardware when the format of the token response is correct. Cleared by hardware when the format of the token response is not correct. Reception mode Set by hardware when the format of the frame is correct. Cleared by hardware when the format of the frame is not correct. CRC7 Status Bit Set by hardware when the CRC7 computed in the response is correct. Cleared by hardware when the CRC7 computed in the response is not correct. This bit is not relevant when CRCDIS is set. 1 0 RESPFS CFLCK Response Format Status Bit Set by hardware when the format of a response is correct. Cleared by hardware when the format of a response is not correct. Command FIFO Lock Bit Set by hardware to signal user not to write in the transmit command FIFO: busy state. Cleared by hardware to signal user the transmit command FIFO is available: idle state. Reset Value = 0000 0000b 106 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 99. MMINT Register MMINT (S:E7h Read Only) - MMC Interrupt Register 7 6 5 4 3 2 1 0 MCBI EORI EOCI EOFI F2FI F1FI F2EI F1EI Bit Number Bit Mnemonic Description 7 MCBI MMC Card Busy Interrupt Flag Set by hardware when the card enters or exits its busy state (when the busy signal is asserted or deasserted on the data line). Cleared when reading MMINT. 6 EORI End of Response Interrupt Flag Set by hardware at the end of response reception. Cleared when reading MMINT. 5 EOCI End of Command Interrupt Flag Set by hardware at the end of command transmission. Clear when reading MMINT. 4 EOFI End of Frame Interrupt Flag Set by hardware at the end of frame (stream or block) transfer. Clear when reading MMINT. 3 F2FI FIFO 2 Full Interrupt Flag Set by hardware when second FIFO becomes full. Cleared by hardware when second FIFO becomes empty. 2 F1FI FIFO 1 Full Interrupt Flag Set by hardware when first FIFO becomes full. Cleared by hardware when first FIFO becomes empty. 1 F2EI FIFO 2 Empty Interrupt Flag Set by hardware when second FIFO becomes empty. Cleared by hardware when second FIFO becomes full. 0 F1EI FIFO 1 Empty Interrupt Flag Set by hardware when first FIFO becomes empty. Cleared by hardware when first FIFO becomes full. Reset Value = 0000 0011b 107 4109C-8051-03/02 Table 100. MMMSK Register MMMSK (S:DFh) - MMC Interrupt Mask Register 7 6 5 4 3 2 1 0 MCBM EORM EOCM EOFM F2FM F1FM F2EM F1EM Bit Number Bit Mnemonic Description 7 MCBM MMC Card Busy Interrupt Mask Bit Set to prevent MCBI flag from generating an MMC interrupt. Clear to allow MCBI flag to generate an MMC interrupt. 6 EORM End Of Response Interrupt Mask Bit Set to prevent EORI flag from generating an MMC interrupt. Clear to allow EORI flag to generate an MMC interrupt. 5 EOCM End Of Command Interrupt Mask Bit Set to prevent EOCI flag from generating an MMC interrupt. Clear to allow EOCI flag to generate an MMC interrupt. 4 EOFM End Of Frame Interrupt Mask Bit Set to prevent EOFI flag from generating an MMC interrupt. Clear to allow EOFI flag to generate an MMC interrupt. 3 F2FM FIFO 2 Full Interrupt Mask Bit Set to prevent F2FI flag from generating an MMC interrupt. Clear to allow F2FI flag to generate an MMC interrupt. 2 F1FM FIFO 1 Full Interrupt Mask Bit Set to prevent F1FI flag from generating an MMC interrupt. Clear to allow F1FI flag to generate an MMC interrupt. 1 F2EM FIFO 2 Empty Interrupt Mask Bit Set to prevent F2EI flag from generating an MMC interrupt. Clear to allow F2EI flag to generate an MMC interrupt. 0 F1EM FIFO 1 Empty Interrupt Mask Bit Set to prevent F1EI flag from generating an MMC interrupt. Clear to allow F1EI flag to generate an MMC interrupt. Reset Value = 1111 1111b Table 101. MMCMD Register MMCMD (S:DDh) - MMC Command Register 7 6 5 4 3 2 1 0 MC7 MC6 MC5 MC4 MC3 MC2 MC1 MC0 Bit Number 7-0 Bit Mnemonic Description MC7:0 MMC Command Receive Byte Output (read) register of the response FIFO. MMC Command Transmit Byte Input (write) register of the command FIFO. Reset Value = 1111 1111b 108 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 102. MMDAT Register MMDAT (S:DCh) - MMC Data Register 7 6 5 4 3 2 1 0 MD7 MD6 MD5 MD4 MD3 MD2 MD1 MD0 Bit Number 7-0 Bit Mnemonic Description MD7:0 MMC Data Byte Input (write) or output (read) register of the data FIFO. Reset Value = 1111 1111b Table 103. MMCLK Register MMCLK (S:EDh) - MMC Clock Divider Register 7 6 5 4 3 2 1 0 MMCD7 MMCD6 MMCD5 MMCD4 MMCD3 MMCD2 MMCD1 MMCD0 Bit Number 7-0 Bit Mnemonic Description MMCD7:0 MMC Clock Divider 8-bit divider for MMC clock generation. Reset Value = 0000 0000b 109 4109C-8051-03/02 IDE/ATAPI Interface The AT8xC51SND1A provides an IDE/ATAPI interface allowing connection of devices such as CD-ROM reader, CompactFlash cards, Hard Disk Drive, etc. It consists of a 16bit data transfer (read or write) between the AT8xC51SND1A and the IDE device. Description The IDE interface mode is enabled by setting the EXT16 bit in AUXR (see Figure 13, page 23). As soon as this bit is set, all MOVX instructions read or write are done in a 16bit mode compare to the standard 8-bit mode. P0 carries the low order multiplexed address and data bus (A7:0, D7:0) while P2 carries the high order multiplexed address and data bus (A15:8, D15:8). When writing data in IDE mode, the ACC contains D7:0 data (as in 8-bit mode) while DAT16H register (see Table 105) contains D15:8 data. When reading data in IDE mode, D7:0 data is returned in ACC while D15:8 data is returned in DAT16H. Figure 22 shows the IDE read bus cycle while Figure 23 shows the IDE write bus cycle. For simplicity, these figures depict the bus cycle waveforms in idealized form and do not provide precise timing information. For IDE bus cycle timing parameters refer to the Section "AC Characteristics" of the AT8xC51SND1A datasheet. IDE cycle takes 6 CPU clock periods which is equivalent to 12 oscillator clock periods in standard mode or 6 oscillator clock periods in X2 mode. For further information on X2 mode, refer to the Section "X2 Feature", page 4. Slow IDE devices can be accessed by stretching the read and write cycles. This is done using the M0 bit in AUXR. Setting this bit changes the width of the RD# and WR# signals from 3 to 15 CPU clock periods. Figure 22. IDE Read Waveforms CPU Clock ALE RD#1 P0 P2 Notes: 110 P2 DPL or Ri D7:0 DPH or P22,3 D15:8 P2 1. RD# signal may be stretched using M0 bit in AUXR register. 2. When executing MOVX @Ri instruction, P2 outputs SFR content. 3. When executing MOVX @DPTR instruction, if DPHDIS is set (Page Access Mode), P2 outputs SFR content instead of DPH. AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Figure 23. IDE Write Waveforms CPU Clock ALE WR#1 P0 P2 Notes: IDE Device Connection P2 DPL or Ri D7:0 DPH or P22,3 D15:8 P2 1. WR# signal may be stretched using M0 bit in AUXR register. 2. When executing MOVX @Ri instruction, P2 outputs SFR content. 3. When executing MOVX @DPTR instruction, if DPHDIS is set (Page Access Mode), P2 outputs SFR content instead of DPH. Figure 24 and Figure 25 show two examples on how to interface up to two IDE devices to the AT8xC51SND1A. In both examples P0 carries IDE low order data bits D7:0, P2 carries IDE high order data bits D15:8, while RD# and WR# signals are respectively connected to the IDE nIOR and nIOW signals. Other IDE control signals are generated by the address latch outputs in the first example while they are generated by some port I/Os in the second one. Figure 24. IDE Device Connection Example 1 AT8xC51SND1A IDE Device 0 P2 P0 Latch ALE RD# WR# IDE Device 1 D15-8 D15-8 D7:0 D7:0 A2:0 nCS1:0 nRESET nIOR nIOW A2:0 nCS1:0 nRESET nIOR nIOW Figure 25. IDE Device Connection Example 2 AT8xC51SND1A IDE Device 0 IDE Device 1 P2/A15:8 D15-8 D15-8 P0/AD7:0 D7:0 D7:0 A2:0 nCS1:0 nRESET nIOR nIOW A2:0 nCS1:0 nRESET nIOR nIOW P4.2:0 P4.4:3 P4.5 RD# WR# 111 4109C-8051-03/02 Table 104. External Data Memory Interface Signals Registers Signal Name Type Alternate Function A15:8 I/O Address Lines Upper address lines for the external bus. Multiplexed higher address and data lines for the IDE interface. P2.7:0 AD7:0 I/O Address/Data Lines Multiplexed lower address and data lines for the IDE interface. P0.7:0 ALE O Address Latch Enable ALE signals indicates that valid address information is available on lines AD7:0. RD# O Read Read signal output to external data memory. P3.7 WR# O Write Write signal output to external memory. P3.6 Description - Table 105. DAT16H Register DAT16H (S:F9h) - Data 16 High Order Byte 7 6 5 4 3 2 1 0 D15 D14 D13 D12 D11 D10 D9 D8 Bit Number 7-0 Bit Mnemonic Description D15:8 Data 16 High Order Byte When EXT16 bit is set, DAT16H is set by software with the high order data byte prior any MOVX write instruction. When EXT16 bit is set, DAT16H contains the high order data byte after any MOVX read instruction. Reset Value = 0000 0000b 112 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Serial I/O Port The serial I/O port in the AT8xC51SND1A provides both synchronous and asynchronous communication modes. It operates as a Synchronous Receiver and Transmitter in one single mode (Mode 0) and operates as an Universal Asynchronous Receiver and Transmitter (UART) in three full-duplex modes (Modes 1, 2 and 3). Asynchronous modes support framing error detection and multiprocessor communication with automatic address recognition. Mode Selection SM0 and SM1 bits in SCON register (see Figure 108) are used to select a mode among the single synchronous and the three asynchronous modes according to Table 106. Table 106. Serial I/O Port Mode Selection Baud Rate Generator SM0 SM1 Mode Description Baud Rate 0 0 0 Synchronous Shift Register Fixed/Variable 0 1 1 8-bit UART Variable 1 0 2 9-bit UART Fixed 1 1 3 9-bit UART Variable Depending on the mode and the source selection, the baud rate can be generated from either the Timer 1 or the Internal Baud Rate Generator. The Timer 1 can be used in Modes 1 and 3 while the Internal Baud Rate Generator can be used in Modes 0, 1 and 3. The addition of the Internal Baud Rate Generator allows freeing of the Timer 1 for other purposes in the application. It is highly recommended to use the Internal Baud Rate Generator as it allows higher and more accurate baud rates than Timer 1. Baud rate formulas depend on the modes selected and are given in the following mode sections. Timer 1 When using Timer 1, the Baud Rate is derived from the overflow of the timer. As shown in Figure 57 Timer 1 is used in its 8-bit auto-reload mode (detailed in Section "Mode 2 (8-bit Timer with Auto-Reload)", page 47). SMOD1 bit in PCON register allows doubling of the generated baud rate. Figure 57. Timer 1 Baud Rate Generator Block Diagram PER CLOCK /6 0 1 TL1 (8 bits) T1 Overflow /2 0 To serial Port 1 C/T1# TMOD.6 SMOD1 INT1# PCON.7 GATE1 TMOD.7 TR1 T1 CLOCK TH1 (8 bits) TCON.6 113 4109C-8051-03/02 Internal Baud Rate Generator When using the Internal Baud Rate Generator, the Baud Rate is derived from the overflow of the timer. As shown in Figure 58 the Internal Baud Rate Generator is an 8-bit auto-reload timer feed by the peripheral clock or by the peripheral clock divided by 6 depending on the SPD bit in BDRCON register (see Table 112). The Internal Baud Rate Generator is enabled by setting BBR bit in BDRCON register. SMOD1 bit in PCON register allows doubling of the generated baud rate. Figure 58. Internal Baud Rate Generator Block Diagram PER CLOCK /6 0 BRG (8 bits) 1 Overflow /2 0 To serial Port 1 SPD BRR BDRCON.1 BDRCON.4 SMOD1 PCON.7 IBRG CLOCK BRL (8 bits) Synchronous Mode (Mode 0) Mode 0 is a half-duplex, synchronous mode, which is commonly used to expand the I/0 capabilities of a device with shift registers. The transmit data (TXD) pin outputs a set of eight clock pulses while the receive data (RXD) pin transmits or receives a byte of data. The 8-bit data are transmitted and received least-significant bit (LSB) first. Shifts occur at a fixed Baud Rate (see Section "Baud Rate Selection (Mode 0)", page 115). Figure 59 shows the serial port block diagram in Mode 0. Figure 59. Serial I/O Port Block Diagram (Mode 0) SCON.6 SCON.7 SM1 SM0 SBUF Tx SR Mode Decoder RXD M3 M2 M1 M0 SBUF Rx SR Mode Controller PER CLOCK Transmission (Mode 0) 114 TI RI SCON.1 SCON.0 BRG CLOCK Baud Rate Controller TXD To start a transmission mode 0, write to SCON register clearing bits SM0, SM1. As shown in Figure 26, writing the byte to transmit to SBUF register starts the transmission. Hardware shifts the LSB (D0) onto the RXD pin during the first clock cycle composed of a high level then low level signal on TXD. During the eighth clock cycle the MSB (D7) is on the RXD pin. Then, hardware drives the RXD pin high and asserts TI to indicate the end of the transmission. AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Figure 26. Transmission Waveforms (Mode 0) TXD Write to SBUF RXD D0 D1 D2 D3 D4 D5 D6 D7 TI Reception (Mode 0) To start a reception in mode 0, write to SCON register clearing SM0, SM1 and RI bits and setting the REN bit. As shown in Figure 27, Clock is pulsed and the LSB (D0) is sampled on the RXD pin. The D0 bit is then shifted into the shift register. After eight sampling, the MSB (D7) is shifted into the shift register, and hardware asserts RI bit to indicate a completed reception. Software can then read the received byte from SBUF register. Figure 27. Reception Waveforms (Mode 0) TXD Set REN, Clear RI Write to SCON RXD D0 D1 D2 D3 D4 D5 D6 D7 RI Baud Rate Selection (Mode 0) In mode 0, the baud rate can be either fixed or variable. As shown in Figure 28, the selection is done using M0SRC bit in BDRCON register. Figure 29 gives the baud rate calculation formulas for each baud rate source. Figure 28. Baud Rate Source Selection (mode 0) PER CLOCK /6 0 To serial Port 1 IBRG CLOCK M0SRC BDRCON.0 Figure 29. Baud Rate Formulas (Mode 0) Baud_Rate= Baud_Rate= FPER 6 a. Fixed Formula BRL= 256 - 2SMOD1 FPER 6(1-SPD) 32 (256 -BRL) 2SMOD1 FPER 6(1-SPD) 32 Baud_Rate b. Variable Formula 115 4109C-8051-03/02 Asynchronous Modes (Modes 1, 2 and 3) The Serial Port has one 8-bit and two 9-bit asynchronous modes of operation. Figure 60 shows the Serial Port block diagram in such asynchronous modes. Figure 60. Serial I/O Port Block Diagram (Modes 1, 2 and 3) SCON.6 SCON.7 SCON.3 SM1 SM0 TB8 Mode Decoder SBUF Tx SR TXD Rx SR RXD M3 M2 M1 M0 T1 CLOCK Mode & Clock Controller IBRG CLOCK SBUF Rx PER CLOCK RB8 SCON.2 SM2 TI RI SCON.4 SCON.1 SCON.0 Mode 1 Mode 1 is a full-duplex, asynchronous mode. The data frame (see Figure 61) consists of 10 bits: one start, eight data bits and one stop bit. Serial data is transmitted on the TXD pin and received on the RXD pin. When a data is received, the stop bit is read in the RB8 bit in SCON register. Figure 61. Data Frame Format (Mode 1) Mode 1 D0 D1 D2 D3 Start bit Modes 2 and 3 D4 D5 D6 D7 8-bit data Stop bit Modes 2 and 3 are full-duplex, asynchronous modes. The data frame (see Figure 62) consists of 11 bits: one start bit, eight data bits (transmitted and received LSB first), one programmable ninth data bit and one stop bit. Serial data is transmitted on the TXD pin and received on the RXD pin. On receive, the ninth bit is read from RB8 bit in SCON register. On transmit, the ninth data bit is written to TB8 bit in SCON register. Alternatively, you can use the ninth bit as a command/data flag. Figure 62. Data Frame Format (Modes 2 and 3) Modes 2 and 3 D0 Start bit D1 D2 D3 D4 9-bit data D5 D6 D7 D8 Stop bit Transmission (Modes 1, 2 and 3) To initiate a transmission, write to SCON register, setting SM0 and SM1 bits according to Table 106, and setting the ninth bit by writing to TB8 bit. Then, writing the byte to be transmitted to SBUF register starts the transmission. Reception (Modes 1, 2 and 3) To prepare for reception, write to SCON register, setting SM0 and SM1 bits according to Table 106, and set the REN bit. The actual reception is then initiated by a detected highto-low transition on the RXD pin. 116 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Framing Error Detection (Modes 1, 2 and 3) Framing error detection is provided for the three asynchronous modes. To enable the framing bit error detection feature, set SMOD0 bit in PCON register as shown in Figure 63. When this feature is enabled, the receiver checks each incoming data frame for a valid stop bit. An invalid stop bit may result from noise on the serial lines or from simultaneous transmission by two devices. If a valid stop bit is not found, the software sets FE bit in SCON register. Software may examine FE bit after each reception to check for data errors. Once set, only software or a chip reset clear FE bit. Subsequently received frames with valid stop bits cannot clear FE bit. When the framing error detection feature is enabled, RI rises on stop bit instead of the last data bit as detailed in Figure 67. Figure 63. Framing Error Block Diagram Framing Error Controller FE 1 SM0/FE 0 SCON.7 SM0 SMOD0 PCON.6 Baud Rate Selection (Modes 1 and 3) In modes 1 and 3, the Baud Rate is derived either from the Timer 1 or the Internal Baud Rate Generator and allows different baud rate in reception and transmission. As shown in Figure 64 the selection is done using RBCK and TBCK bits in BDRCON register. Figure 65 gives the baud rate calculation formulas for each baud rate source while Table 107 details Internal Baud Rate Generator configuration for different peripheral clock frequencies and giving baud rates closer to the standard baud rates. Figure 64. Baud Rate Source Selection (Modes 1 and 3) T1 CLOCK IBRG CLOCK T1 CLOCK 0 / 16 1 To serial reception Port IBRG CLOCK 0 / 16 1 RBCK TBCK BDRCON.2 BDRCON.3 To serial transmission Port Figure 65. Baud Rate Formulas (Modes 1 and 3) Baud_Rate= BRL= 256 - 2SMOD1 FPER 6(1-SPD) 32 (256 -BRL) 6 2SMOD1 FPER 32 Baud_Rate (1-SPD) a. IBRG Formula Baud_Rate= 2SMOD1 FPER 6 32 (256 -TH1) TH1= 256 - 2SMOD1 FPER 192 Baud_Rate b. T1 Formula 117 4109C-8051-03/02 Table 107. Internal Baud Rate Generator Value FPER = 6 MHz(1) FPER = 8 MHz(1) FPER = 10 MHz(1) Baud Rate SPD SMOD1 BRL Error% SPD SMOD1 BRL Error% SPD SMOD1 BRL Error% 115200 - - - - - - - - - - - - 57600 - - - - 1 1 247 3.55 1 1 245 1.36 38400 1 1 246 2.34 1 1 243 0.16 1 1 240 1.73 19200 1 1 236 2.34 1 1 230 0.16 1 1 223 1.36 9600 1 1 217 0.16 1 1 204 0.16 1 1 191 0.16 4800 1 1 178 0.16 1 1 152 0.16 1 1 126 0.16 FPER = 12 MHz(2) FPER = 16 MHz(2) FPER = 20 MHz(2) Baud Rate SPD SMOD1 BRL Error% SPD SMOD1 BRL Error% SPD SMOD1 BRL Error% 115200 - - - - 1 1 247 3.55 1 1 245 1.36 57600 1 1 243 0.16 1 1 239 2.12 1 1 234 1.36 38400 1 1 236 2.34 1 1 230 0.16 1 1 223 1.36 19200 1 1 217 0.16 1 1 204 0.16 1 1 191 0.16 9600 1 1 178 0.16 1 1 152 0.16 1 1 126 0.16 4800 1 1 100 0.16 1 1 48 0.16 1 0 126 0.16 Notes: 1. These frequencies are achieved in X1 mode, FPER = F OSC / 2. 2. These frequencies are achieved in X2 mode, FPER = F OSC. Baud Rate Selection (Mode 2) In mode 2, the baud rate can only be programmed to two fixed values: 1/16 or 1/32 of the peripheral clock frequency. As shown in Figure 30 the selection is done using SMOD1 bit in PCON register. Figure 31 gives the baud rate calculation formula depending on the selection. Figure 30. Baud Rate Generator Selection (mode 2) PER CLOCK /2 0 / 16 To serial Port 1 SMOD1 PCON.7 118 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Figure 31. Baud Rate Formula (Mode 2) Baud_Rate= Multiprocessor Communication (Modes 2 and 3) 2SMOD1 FPER 32 Modes 2 and 3 provide a ninth-bit mode to facilitate multiprocessor communication. To enable this feature, set SM2 bit in SCON register. When the multiprocessor communication feature is enabled, the Serial Port can differentiate between data frames (ninth bit clear) and address frames (ninth bit set). This allows the AT8xC51SND1A to function as a slave processor in an environment where multiple slave processors share a single serial line. When the multiprocessor communication feature is enabled, the receiver ignores frames with the ninth bit clear. The receiver examines frames with the ninth bit set for an address match. If the received address matches the slaves address, the receiver hardware sets RB8 and RI bits in SCON register, generating an interrupt. The addressed slave's software then clears SM2 bit in SCON register and prepares to receive the data bytes. The other slaves are unaffected by these data bytes because they are waiting to respond to their own addresses. Automatic Address Recognition The automatic address recognition feature is enabled when the multiprocessor communication feature is enabled (SM2 bit in SCON register is set). Implemented in hardware, automatic address recognition enhances the multiprocessor communication feature by allowing the Serial Port to examine the address of each incoming command frame. Only when the Serial Port recognizes its own address, the receiver sets RI bit in SCON register to generate an interrupt. This ensures that the CPU is not interrupted by command frames addressed to other devices. If desired, you may enable the automatic address recognition feature in mode 1. In this configuration, the stop bit takes the place of the ninth data bit. Bit RI is set only when the received command frame address matches the device's address and is terminated by a valid stop bit. To support automatic address recognition, a device is identified by a given address and a broadcast address. Note: Given Address The multiprocessor communication and automatic address recognition features cannot be enabled in mode 0 (i.e, setting SM2 bit in SCON register in mode 0 has no effect). Each device has an individual address that is specified in SADDR register; the SADEN register is a mask byte that contains don't-care bits (defined by zeros) to form the device's given address. The don't-care bits provide the flexibility to address one or more slaves at a time. The following example illustrates how a given address is formed. To address a device by its individual address, the SADEN mask byte must be 1111 1111b. For example: SADDR = 0101 0110b SADEN = 1111 1100b Given = 0101 01XXb The following is an example of how to use given addresses to address different slaves: Slave A:SADDR = 1111 0001b SADEN = 1111 1010b 119 4109C-8051-03/02 Given = 1111 0X0Xb Slave B:SADDR = 1111 0011b SADEN = 1111 1001b Given = 1111 0XX1b Slave C:SADDR = 1111 0010b SADEN = 1111 1101b Given = 1111 00X1b The SADEN byte is selected so that each slave may be addressed separately. For slave A, bit 0 (the LSB) is a don't-care bit; for slaves B and C, bit 0 is a 1. To communicate with slave A only, the master must send an address where bit 0 is clear (e.g. 1111 0000B). For slave A, bit 1 is a 0; for slaves B and C, bit 1 is a don't care bit. To communicate with slaves A and B, but not slave C, the master must send an address with bits 0 and 1 both set (e.g. 1111 0011B). To communicate with slaves A, B and C, the master must send an address with bit 0 set, bit 1 clear, and bit 2 clear (e.g. 1111 0001B). Broadcast Address A broadcast address is formed from the logical OR of the SADDR and SADEN registers with zeros defined as don't-care bits, e.g.: SADDR = 0101 0110b SADEN = 1111 1100b (SADDR | SADEN)=1111 111Xb The use of don't-care bits provides flexibility in defining the broadcast address, however in most applications, a broadcast address is FFh. The following is an example of using broadcast addresses: Slave A:SADDR = 1111 0001b SADEN = 1111 1010b Given = 1111 1X11b, Slave B:SADDR = 1111 0011b SADEN = 1111 1001b Given = 1111 1X11b, Slave C:SADDR = 1111 0010b SADEN = 1111 1101b Given = 1111 1111b, For slaves A and B, bit 2 is a don't care bit; for slave C, bit 2 is set. To communicate with all of the slaves, the master must send the address FFh. To communicate with slaves A and B, but not slave C, the master must send the address FBh. Reset Address 120 On reset, the SADDR and SADEN registers are initialized to 00h, i.e. the given and broadcast addresses are XXXX XXXXb (all don't-care bits). This ensures that the Serial Port is backwards compatible with the 80C51 microcontrollers that do not support automatic address recognition. AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Interrupt The Serial I/O Port handles two interrupt sources that are the "end of reception" (RI in SCON) and "end of transmission" (TI in SCON) flags. As shown in Figure 66 these flags are combined together to appear as a single interrupt source for the C51 core. Flags must be cleared by software when executing the serial interrupt service routine. The serial interrupt is enabled by setting ES bit in IEN0 register. This assumes interrupts are globally enabled by setting EA bit in IEN0 register. Depending on the selected mode and weather the framing error detection is enabled or not, RI flag is set during the stop bit or during the ninth bit as detailed in Figure 67. Figure 66. Serial I/O Interrupt System SCON.0 RI Serial I/O Interrupt Request TI SCON.1 ES IEN0.4 Figure 67. Interrupt Waveforms a. Mode 1 RXD D0 D1 D2 Start bit D3 D4 D5 D6 D7 8-bit data Stop bit RI SMOD0 = X FE SMOD0 = 1 b. Mode 2 and 3 RXD D0 Start bit D1 D2 D3 D4 9-bit data D5 D6 D7 D8 Stop bit RI SMOD0 = 0 RI SMOD0 = 1 FE SMOD0 = 1 121 4109C-8051-03/02 Registers Table 108. SCON Register SCON (S:98h) - Serial Control Register 7 6 5 4 3 2 1 0 FE/SM0 OVR/SM1 SM2 REN TB8 RB8 TI RI Bit Number Bit Mnemonic Description FE 7 Framing Error Bit To select this function, set SMOD0 bit in PCON register. Set by hardware to indicate an invalid stop bit. Must be cleared by software. SM0 Serial Port Mode Bit 0 Refer to Table 106 for mode selection. SM1 Serial Port Mode Bit 1 Refer to Table 106 for mode selection. 5 SM2 Serial Port Mode Bit 2 Set to enable the multiprocessor communication and automatic address recognition features. Clear to disable the multiprocessor communication and automatic address recognition features. 4 REN Receiver Enable Bit Set to enable reception. Clear to disable reception. 3 TB8 Transmit Bit 8 Modes 0 and 1: Not used. Modes 2 and 3: Software writes the ninth data bit to be transmitted to TB8. 2 RB8 Receiver Bit 8 Mode 0: Not used. Mode 1 (SM2 cleared): Set or cleared by hardware to reflect the stop bit received. Modes 2 and 3 (SM2 set): Set or cleared by hardware to reflect the ninth bit received. 1 TI Transmit Interrupt Flag Set by the transmitter after the last data bit is transmitted. Must be cleared by software. 0 RI Receive Interrupt Flag Set by the receiver after the stop bit of a frame has been received. Must be cleared by software. 6 Reset Value = 0000 0000b 122 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 109. SBUF Register SBUF (S:99h) - Serial Buffer Register 7 6 5 4 3 2 1 0 SD7 SD6 SD5 SD4 SD3 SD2 SD1 SD0 Bit Number 7-0 Bit Mnemonic Description SD7:0 Serial Data Byte Read the last data received by the Serial I/O Port. Write the data to be transmitted by the Serial I/O Port. Reset value = XXXX XXXXb Table 110. SADDR Register SADDR (S:A9h) - Slave Individual Address Register 7 6 5 4 3 2 1 0 SAD7 SAD6 SAD5 SAD4 SAD3 SAD2 SAD1 SAD0 Bit Number 7-0 Bit Mnemonic Description SAD7:0 Slave Individual Address. Reset Value = 0000 0000b Table 111. SADEN Register SADEN (S:B9h) - Slave Individual Address Mask Byte Register 7 6 5 4 3 2 1 0 SAE7 SAE6 SAE5 SAE4 SAE3 SAE2 SAE1 SAE0 Bit Number 7-0 Bit Mnemonic Description SAE7:0 Slave Address Mask Byte. Reset Value = 0000 0000b 123 4109C-8051-03/02 Table 112. BDRCON Register BDRCON (S:92h) - Baud Rate Generator Control Register 7 6 5 4 3 2 1 0 - - - BRR TBCK RBCK SPD M0SRC Bit Number Bit Mnemonic Description Reserved The value read from these bits are indeterminate. Do not set these bits. 7-5 - 4 BRR Baud Rate Run Bit Set to enable the baud rate generator. Clear to disable the baud rate generator. 3 TBCK Transmission Baud Rate Selection Bit Set to select the baud rate generator as transmission baud rate generator. Clear to select the Timer 1 as transmission baud rate generator. 2 RBCK Reception Baud Rate Selection Bit Set to select the baud rate generator as reception baud rate generator. Clear to select the Timer 1 as reception baud rate generator. 1 SPD 0 M0SRC Baud Rate Speed Bit Set to select high speed baud rate generation. Clear to select low speed baud rate generation. Mode 0 Baud Rate Source Bit Set to select the variable baud rate generator in Mode 0. Clear to select fixed baud rate in Mode 0. Reset Value = XXX0 0000b Table 113. BRL Register BRL (S:91h) - Baud Rate Generator Reload Register 7 6 5 4 3 2 1 0 BRL7 BRL6 BRL5 BRL4 BRL3 BRL2 BRL1 BRL0 Bit Number 7-0 Bit Mnemonic Description BRL7:0 Baud Rate Reload Value. Reset Value = 0000 0000b 124 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Synchronous Peripheral Interface The AT8xC51SND1A implements a Synchronous Peripheral Interface with master and slave modes capability. Figure 68 shows an SPI bus configuration using the AT8xC51SND1A as master connected to slave peripherals while Figure 69 shows an SPI bus configuration using the AT8xC51SND1A as slave of an other master. The bus is made of three wires connecting all the devices together: * Master Output Slave Input (MOSI): it is used to transfer data in series from the master to a slave. It is driven by the master. * Master Input Slave Output (MISO): it is used to transfer data in series from a slave to the master. It is driven by the selected slave. * Serial Clock (SCK): it is used to synchronize the data transmission both in and out the devices through their MOSI and MISO lines. It is driven by the master for eight clock cycles which allows to exchange one byte on the serial lines. Each slave peripheral is selected by one Slave Select pin (SS#). If there is only one slave, it may be continuously selected with SS# tied to a low level. Otherwise, the AT8xC51SND1A may select each device by software through port pins (Pn.x). Special care should be taken not to select two slaves at the same time to avoid bus conflicts. Figure 68. Typical Master SPI Bus Configuration Pn.z Pn.y SS# DataFlash 1 Pn.x AT8xC51SND1A P4.0 P4.1 P4.2 SO SI SCK SS# DataFlash 2 SO SI SCK SS# SO LCD Controller SI SCK MISO MOSI SCK Figure 69. Typical Slave SPI Bus Configuration SS# SSn# SS1# SS0# MASTER SS# SO Slave 1 SI SCK SS# SO Slave 2 AT8xC51SND1A Slave n SI MISO MOSI SCK SCK MISO MOSI SCK 125 4109C-8051-03/02 Description The SPI controller interfaces with the C51 core through three special function registers: SPCON, the SPI control register (see Table 115); SPSTA, the SPI status register (see Table 116); and SPDAT, the SPI data register (see Table 117). Master Mode The SPI operates in master mode when the MSTR bit in SPCON is set. Figure 70 shows the SPI block diagram in master mode. Only a master SPI module can initiate transmissions. Software begins the transmission by writing to SPDAT. Writing to SPDAT writes to the shift register while reading SPDAT reads an intermediate register updated at the end of each transfer. The byte begins shifting out on the MOSI pin under the control of the bit rate generator. This generator also controls the shift register of the slave peripheral through the SCK output pin. As the byte shifts out, another byte shifts in from the slave peripheral on the MISO pin. The byte is transmitted most significant bit (MSB) first. The end of transfer is signaled by SPIF being set. In case of the AT8xC51SND1A is the only master on the bus, it can be useful not to use SS# pin and get it back to I/O functionality. This is achieved by setting SSDIS bit in SPCON. Figure 70. SPI Master Mode Block Diagram MOSI/P4.1 I 8-bit Shift Register SPDAT WR SCK/P4.2 SPDAT RD Q Internal Bus MISO/P4.0 SS#/P4.3 MODF SSDIS SPCON.5 SPSTA.4 Control and Clock Logic WCOL SPSTA.6 PER CLOCK Bit Rate Generator SPIF SPSTA.7 SPEN SPCON.6 Note: SPR2:0 CPHA CPOL SPCON SPCON.2 SPCON.3 MSTR bit in SPCON is set to select master mode. Slave Mode The SPI operates in slave mode when the MSTR bit in SPCON is cleared and a data has been loaded in SPDAT. Figure 71 shows the SPI block diagram in slave mode. In slave mode, before a data transmission occurs, the SS# pin of the slave SPI must be asserted to low level. SS# must remain low until the transmission of the byte is complete. In the slave SPI module, data enters the shift register through the MOSI pin under the control of the serial clock provided by the master SPI module on the SCK input pin. When the master starts a transmission, the data in the shift register begins shifting out on the MISO pin. The end of transfer is signaled by SPIF being set. In case of the AT8xC51SND1A is the only slave on the bus, it can be useful not to use SS# pin and get it back to I/O functionality. This is achieved by setting SSDIS bit in SPCON. This bit has no effect when CPHA is cleared (see Section "SS# Management", page 128). 126 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Figure 71. SPI Slave Mode Block Diagram MISO/P4.2 I 8-bit Shift Register Q Internal Bus MOSI/P4.1 SPDAT WR SPDAT RD SCK/P4.2 Control and Clock Logic SS#/P4.3 SPIF SPSTA.7 SSDIS SPCON.5 Note: Bit Rate CPHA CPOL SPCON.2 SPCON.3 MSTR bit in SPCON is cleared to select slave mode. The bit rate can be selected from seven predefined bit rates using the SPR2, SPR1 and SPR0 control bits in SPCON according to Table 114. These bit rates are derived from the peripheral clock (F PER ) issued from the Clock Controller block as detailed in Section , page 4. Table 114. Serial Bit Rates Bit Rate (kHz) Vs FPER SPR2 SPR1 SPR0 0 0 0 1 10 MHz1 12 MHz2 16 MHz2 20 MHz2 6 MHz 8 MHz 0 3000 4000 5000 6000 8000 10000 2 0 1 1500 2000 2500 3000 4000 5000 4 0 1 0 750 1000 1250 1500 2000 2500 8 0 1 1 375 500 625 750 1000 1250 16 1 0 0 187.5 250 312.5 375 500 625 32 1 0 1 93.75 125 156.25 187.5 250 312.5 64 1 1 0 46.875 62.5 78.125 93.75 125 156.25 128 1 1 1 6000 8000 10000 12000 16000 20000 1 Notes: Data Transfer 1 FPER Divider 1. These frequencies are achieved in X1 mode, FPER = FOSC / 2. 2. These frequencies are achieved in X2 mode, FPER = FOSC. The Clock Polarity bit (CPOL in SPCON) defines the default SCK line level in idle state1 while the Clock Phase bit (CPHA in SPCON) defines the edges on which the input data are sampled and the edges on which the output data are shifted (see Figure 72 and Figure 73). The SI signal is output from the selected slave and the SO signal is the output from the master. The AT8xC51SND1A is capturing data from the SI line while the selected slave is capturing data from the SO line. For simplicity, the accompanying figures depict the SPI waveforms in idealized form and do not provide precise timing information. For timing parameters refer to the Section "AC Characteristics" of the AT8xC51SND1A datasheet. Note: 1. When the peripheral is disabled (SPEN = 0), default SCK line is high level. 127 4109C-8051-03/02 Figure 72. Data Transmission Format (CPHA = 0) 1 2 3 4 5 6 7 8 MSB bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 LSB bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 LSB SCK cycle number SPEN (internal) SCK (CPOL = 0) SCK (CPOL = 1) MOSI (from master) MISO (from slave) MSB SS# (to slave) Capture point Figure 73. Data Transmission Format (CPHA = 1) 1 2 3 4 5 6 7 8 MOSI (from master) MSB bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 LSB MISO (from slave) MSB bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 SCK cycle number SPEN (internal) SCK (CPOL = 0) SCK (CPOL = 1) LSB SS# (to slave) Capture point SS# Management Figure 72 shows an SPI transmission with CPHA = 0, where the first SCK edge is the MSB capture point. Therefore the slave starts to output its MSB as soon as it is selected: SS# asserted to low level. SS# must then be deasserted between each byte transmission (see Figure 32). SPDAT must be loaded with a data before SS# is asserted again. Figure 73 shows an SPI transmission with CPHA = 1, where the first SCK edge is used by the slave as a start of transmission signal. Therefore SS# may remain asserted between each byte transmission (see Figure 32). 128 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Figure 32. SS# Timing Diagram SI/SO Byte 1 Byte 2 Byte 3 SS# (CPHA = 0) SS# (CPHA = 1) Error Conditions The following flags signal the SPI error conditions: * MODF in SPSTA signals a mode fault. MODF flag is relevant only in master mode when SS# usage is enabled (SSDIS bit cleared). It signals when set that an other master on the bus has asserted SS# pin and so, may create a conflict on the bus with two master sending data at the same time. A mode fault automatically disables the SPI (SPEN cleared) and configures the SPI in slave mode (MSTR cleared). MODF flag can trigger an interrupt as explained in Section "Interrupt", page 129. MODF flag is cleared by reading SPSTA and re-configuring SPI by writing to SPCON. * WCOL in SPSTA signals a write collision. WCOL flag is set when SPDAT is loaded while a transfer is on-going. In this case data is not written to SPDAT and transfer continue uninterrupted. WCOL flag does not trigger any interrupt and is relevant jointly with SPIF flag. WCOL flag is cleared after reading SPSTA and writing new data to SPDAT while no transfer is on-going. Interrupt The SPI handles two interrupt sources that are the "end of transfer" and the "mode fault" flags. As shown in Figure 33 these flags are combined together to appear as a single interrupt source for the C51 core. The SPIF flag is set at the end of an 8-bit shift in and out and is cleared by reading SPSTA and then reading from or writing to SPDAT. The MODF flag is set in case of mode fault error and is cleared by reading SPSTA and then writing to SPCON. The SPI interrupt is enabled by setting ESPI bit in IEN1 register. This assumes interrupts are globally enabled by setting EA bit in IEN0 register. Figure 33. SPI Interrupt System SPIF SPI Controller Interrupt Request SPSTA.7 MODF SPSTA.4 ESPI IEN1.2 129 4109C-8051-03/02 Configuration The SPI configuration is made through SPCON. Master Configuration The SPI operates in master mode when the MSTR bit in SPCON is set. Slave Configuration The SPI operates in slave mode when the MSTR bit in SPCON is cleared and a data has been loaded is SPDAT. Data Exchange There are two possible Policies to exchange data in master and slave modes: Master Mode with Polling Policy * polling * interrupts Figure 34 shows the initialization phase and the transfer phase flows using the polling policy. Using this flow prevent any overrun error occurrence. The bit rate is selected according to Table 114. The transfer format depends on the slave peripheral. SS# may be deasserted between transfers depending also on the slave peripheral. SPIF flag is cleared when reading SPDAT (SPSTA has been read before by the "end of transfer" check). This policy provides the fastest effective transmission and is well adapted when communicating at high speed with other Microcontrollers. However, the procedure may then be interrupted at any time by higher priority tasks. 130 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Figure 34. Master SPI Polling Policy Flows SPI Initialization Polling Policy SPI Transfer Polling Policy Disable interrupt SPIE = 0 Select Slave Pn.x = L Select Master Mode MSTR = 1 Start Transfer write data in SPDAT Select Bit Rate program SPR2:0 End Of Transfer? SPIF = 1? Select Format program CPOL & CPHA Get Data Received read SPDAT Enable SPI SPEN = 1 Last Transfer? Deselect Slave Pn.x = H Master Mode with Interrupt Policy Figure 35 shows the initialization phase and the transfer phase flows using the interrupt policy. Using this flow prevent any overrun error occurrence. The bit rate is selected according to Table 114. The transfer format depends on the slave peripheral. SS# may be deasserted between transfers depending also on the slave peripheral. Reading SPSTA at the beginning of the ISR is mandatory for clearing the SPIF flag. Clear is effective when reading SPDAT. 131 4109C-8051-03/02 Figure 35. Master SPI Interrupt Policy Flows SPI Initialization Interrupt Policy SPI Interrupt Service Routine Select Master Mode MSTR = 1 Read Status Read SPSTA Select Bit Rate program SPR2:0 Get Data Received read SPDAT Select Format program CPOL & CPHA Start New Transfer write data in SPDAT Enable interrupt ESPI =1 Last Transfer? Enable SPI SPEN = 1 Deselect Slave Pn.x = H Select Slave Pn.x = L Disable interrupt SPIE = 0 Start Transfer write data in SPDAT Slave Mode with Polling Policy Figure 36 shows the initialization phase and the transfer phase flows using the polling policy. The transfer format depends on the master controller. SPIF flag is cleared when reading SPDAT (SPSTA has been read before by the "end of reception" check). This policy provides the fastest effective transmission and is well adapted when communicating at high speed with other Microcontrollers. However, the procedure may then be interrupted at any time by higher priority tasks. 132 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Figure 36. Slave SPI Polling Policy Flows SPI Initialization Polling Policy Disable interrupt SPIE = 0 SPI Transfer Polling Policy Data Received? SPIF = 1? Select Slave Mode MSTR = 0 Get Data Received read SPDAT Select Format program CPOL & CPHA Prepare Next Transfer write data in SPDAT Enable SPI SPEN = 1 Prepare Transfer write data in SPDAT Slave Mode with Interrupt Policy Figure 35 shows the initialization phase and the transfer phase flows using the interrupt policy. The transfer format depends on the master controller. Reading SPSTA at the beginning of the ISR is mandatory for clearing the SPIF flag. Clear is effective when reading SPDAT. Figure 37. Slave SPI Interrupt Policy Flows SPI Initialization Interrupt Policy SPI Interrupt Service Routine Select Slave Mode MSTR = 0 Get Status Read SPSTA Select Format program CPOL & CPHA Get Data Received read SPDAT Enable interrupt ESPI =1 Prepare New Transfer write data in SPDAT Enable SPI SPEN = 1 Prepare Transfer write data in SPDAT 133 4109C-8051-03/02 Registers Table 115. SPCON Register SPCON (S:C3h) - SPI Control Register 7 6 5 4 3 2 1 0 SPR2 SPEN SSDIS MSTR CPOL CPHA SPR1 SPR0 Bit Number Bit Mnemonic Description 7 SPR2 SPI Rate Bit 2 Refer to Table 114 for bit rate description. 6 SPEN SPI Enable Bit Set to enable the SPI interface. Clear to disable the SPI interface. 5 SSDIS Slave Select Input Disable Bit Set to disable SS# in both master and slave modes. In slave mode this bit has no effect if CPHA = 0. Clear to enable SS# in both master and slave modes. 4 MSTR Master Mode Select Set to select the master mode. Clear to select the slave mode. 3 CPOL 2 CPHA 1-0 SPR1:0 SPI Clock Polarity Bit(1) Set to have the clock output set to high level in idle state. Clear to have the clock output set to low level in idle state. SPI Clock Phase Bit Set to have the data sampled when the clock returns to idle state (see CPOL). Clear to have the data sampled when the clock leaves the idle state (see CPOL). SPI Rate Bits 0 and 1 Refer to Table 114 for bit rate description. Reset Value = 0001 0100b Note: 134 1. When the SPI is disabled, SCK outputs high level. AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 116. SPSTA Register SPSTA (S:C4h) - SPI Status Register 7 6 5 4 3 2 1 0 SPIF WCOL - MODF - - - - Bit Number Bit Mnemonic Description 7 SPIF 6 WCOL 5 - 4 MODF 3:0 - SPI Interrupt Flag Set by hardware when an 8-bit shift is completed. Cleared by hardware when reading or writing SPDAT after reading SPSTA. Write Collision Flag Set by hardware to indicate that a collision has been detected. Cleared by hardware to indicate that no collision has been detected. Reserved The value read from this bit is indeterminate. Do not set this bit. Mode Fault Set by hardware to indicate that the SS# pin is at an appropriate level. Cleared by hardware to indicate that the SS# pin is at an inappropriate level. Reserved The value read from these bits is indeterminate. Do not set these bits. Reset Value = 00000 0000b Table 117. SPDAT Register SPDAT (S:C5h) - Synchronous Serial Data Register 7 6 5 4 3 2 1 0 SPD7 SPD6 SPD5 SPD4 SPD3 SPD2 SPD1 SPD0 Bit Number 7-0 Bit Mnemonic Description SPD7:0 Synchronous Serial Data. Reset Value = XXXX XXXXb 135 4109C-8051-03/02 Two-wire Controller The AT8xC51SND1A implements a two-wire controller supporting the four standard master and slave modes with multimaster capability. Thus it allows connection of slave devices like LCD controller, audio DAC... but also external master controlling where the AT8xC51SND1A is used as a peripheral of a host. The two-wire bus is a bi-directional two-wire serial communication standard. It is designed primarily for simple but efficient integrated circuit control. The system is comprised of two lines, SCL (Serial Clock) and SDA (Serial Data) that carry information between the ICs connected to them. The serial data transfer is limited to 100 Kbit/s in low speed mode, however, some higher bit rates can be achieved depending on the oscillator frequency. Various communication configurations can be designed using this bus. Figure 38 shows a typical two-wire bus configuration using the AT8xC51SND1A in master and slave modes. All the devices connected to the bus can be master and slave. Figure 38. Typical Two-wire Bus Configuration AT8xC51SND1 Master/Slave LCD Display Rp P1.6/SCL P1.7/SDA Description Audio DAC HOST Microprocessor Rp SCL SDA The CPU interfaces to the two-wire logic via the following four 8-bit special function registers: the Synchronous Serial Control register (SSCON SFR, see Table 125), the Synchronous Serial Data register (SSDAT SFR, see Table 127), the Synchronous Serial Status register (SSSTA SFR, see Table 126) and the Synchronous Serial Address register (SSADR SFR, see Table 128). SSCON is used to enable the controller, to program the bit rate (see Table 125), to enable slave modes, to acknowledge or not a received data, to send a START or a STOP condition on the two-wire bus, and to acknowledge a serial interrupt. An hardware reset disables the two-wire controller. SSSTA contains a status code which reflects the status of the two-wire logic and the two-wire bus. The three least significant bits are always zero. The five most significant bits contains the status code. There are 26 possible status codes. When SSSTA contains F8h, no relevant state information is available and no serial interrupt is requested. A valid status code is available in SSSTA after SSI is set by hardware and is still present until SSI has been reset by software. Table 119 to Table 78 give the status for both master and slave modes and miscellaneous states. SSDAT contains a byte of serial data to be transmitted or a byte which has just been received. It is addressable while it is not in process of shifting a byte. This occurs when two-wire logic is in a defined state and the serial interrupt flag is set. Data in SSDAT remains stable as long as SSI is set. While data is being shifted out, data on the bus is simultaneously shifted in; SSDAT always contains the last byte present on the bus. SSADR may be loaded with the 7-bit slave address (7 most significant bits) to which the controller will respond when programmed as a slave transmitter or receiver. The LSB is used to enable general call address (00h) recognition. Figure 74 shows how a data transfer is accomplished on the two-wire bus. 136 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Figure 74. Complete Data Transfer on Two-wire Bus SDA MSB Slave Address SCL 1 2 R/W ACK direction signal bit from receiver 8 Nth data byte 9 S 1 2 ACK signal from receiver 8 9 Clock line held low while serial interrupts are serviced P/S The four operating modes are: * Master Transmitter * Master Receiver * Slave transmitter * Slave receiver Data transfer in each mode of operation are shown in Figure 75 to Figure 78. These figures contain the following abbreviations: A Acknowledge bit (low level at SDA) A Not acknowledge bit (high level on SDA) Data 8-bit data byte S START condition P STOP condition MR Master Receive MT Master Transmit SLA Slave Address GCA General Call Address (00h) R Read bit (high level at SDA) W Write bit (low level at SDA) In Figure 75 to Figure 78, circles are used to indicate when the serial interrupt flag is set. The numbers in the circles show the status code held in SSSTA. At these points, a service routine must be executed to continue or complete the serial transfer. These service routines are not critical since the serial transfer is suspended until the serial interrupt flag is cleared by software. When the serial interrupt routine is entered, the status code in SSSTA is used to branch to the appropriate service routine. For each status code, the required software action and details of the following serial transfer are given in Table 119 to Table 78. 137 4109C-8051-03/02 Bit Rate The bit rate can be selected from seven predefined bit rates or from a programmable bit rate generator using the SSCR2, SSCR1, and SSCR0 control bits in SSCON (see Table 125). The predefined bit rates are derived from the peripheral clock (FPER) issued from the Clock Controller block as detailed in Section "Oscillator", page 4, while bit rate generator is based on timer 1 overflow output. Table 118. Serial Clock Rates Bit Frequency (kHz) SSCR2 SSCR1 SSCR0 FPER = 6 MHz FPER = 8 MHz FPER = 10 MHz FPER Divided By 0 0 0 47 62.5 78.125 256 0 0 1 53.5 71.5 89.3 224 0 1 0 62.5 83 104.2(1) 192 0 1 1 75 100 125(1) 160 1 0 0 12.5 16.5 20.83 960 1 0 1 100 133.3(1) 166.7(1) 120 1 1 0 200(1) 266.7(1) 333.3(1) 60 1 1 0.5 < < 125(1) 0.67 < < 166.7(1) 0.81 < < 208.3(1) 96 (256 - reload value Timer 1) 1 Note: These bit rates are outside of the low speed standard specification limited to 100 kHz but can be used with high speed two-wire components limited to 400 kHz. Master Transmitter Mode In the master transmitter mode, a number of data bytes are transmitted to a slave receiver (see Figure 75). Before the master transmitter mode can be entered, SSCON must be initialized as follows: SSCR2 SSPE SSSTA SSSTO SSI SSAA SSCR1 SSCR0 Bit Rate 1 0 0 0 X Bit Rate Bit Rate SSCR2:0 define the serial bit rate (see Table 118). SSPE must be set to enable the controller. SSSTA, SSSTO and SSI must be cleared. The master transmitter mode may now be entered by setting the SSSTA bit. The twowire logic will now monitor the two-wire bus and generate a START condition as soon as the bus becomes free. When a START condition is transmitted, the serial interrupt flag (SSI bit in SSCON) is set, and the status code in SSSTA is 08h. This status must be used to vector to an interrupt routine that loads SSDAT with the slave address and the data direction bit (SLA+W). The serial interrupt flag (SSI) must then be cleared before the serial transfer can continue. When the slave address and the direction bit have been transmitted and an acknowledgment bit has been received, SSI is set again and a number of status code in SSSTA are possible. There are 18h, 20h or 38h for the master mode and also 68h, 78h or B0h if the slave mode was enabled (SSAA = logic 1). The appropriate action to be taken for each of these status code is detailed in Table 119. This scheme is repeated until a STOP condition is transmitted. SSPE and SSCR2:0 are not affected by the serial transfer and are not referred to in Table 119. After a repeated START condition (state 10h) the controller may switch to the master receiver mode by loading SSDAT with SLA+R. 138 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Master Receiver Mode In the master receiver mode, a number of data bytes are received from a slave transmitter (see Figure 76). The transfer is initialized as in the master transmitter mode. When the START condition has been transmitted, the interrupt routine must load SSDAT with the 7-bit slave address and the data direction bit (SLA+R). The serial interrupt flag (SSI) must then be cleared before the serial transfer can continue. When the slave address and the direction bit have been transmitted and an acknowledgment bit has been received, the serial interrupt flag is set again and a number of status code in SSSTA are possible. There are 40h, 48h or 38h for the master mode and also 68h, 78h or B0h if the slave mode was enabled (SSAA = logic 1). The appropriate action to be taken for each of these status code is detailed in Table 78. This scheme is repeated until a STOP condition is transmitted. SSPE and SSCR2:0 are not affected by the serial transfer and are not referred to in Table 78. After a repeated START condition (state 10h) the controller may switch to the master transmitter mode by loading SSDAT with SLA+W. Slave Receiver Mode In the slave receiver mode, a number of data bytes are received from a master transmitter (see Figure 77). To initiate the slave receiver mode, SSADR and SSCON must be loaded as follows: SSA6 SSA5 SSA4 SSA3 SSA2 SSA1 SSA0 Own Slave Address SSGC X The upper 7 bits are the addresses to which the controller will respond when addressed by a master. If the LSB (SSGC) is set the controller will respond to the general call address (00h); otherwise it ignores the general call address. SSCR2 SSPE SSSTA SSSTO SSI SSAA SSCR1 SSCR0 X 1 0 0 0 1 X X SSCR2:0 have no effect in the slave mode. SSPE must be set to enable the controller. The SSAA bit must be set to enable the own slave address or the general call address acknowledgment. SSSTA, SSSTO and SSI must be cleared. When SSADR and SSCON have been initialized, the controller waits until it is addressed by its own slave address followed by the data direction bit which must be logic 0 (W) for operating in the slave receiver mode. After its own slave address and the W bit have been received, the serial interrupt flag is set and a valid status code can be read from SSSTA. This status code is used to vector to an interrupt service routine, and the appropriate action to be taken for each of these status code is detailed in Table 78 and Table 122. The slave receiver mode may also be entered if arbitration is lost while the controller is in the master mode (see states 68h and 78h). If the SSAA bit is reset during a transfer, the controller will return a not acknowledge (logic 1) to SDA after the next received data byte. While SSAA is reset, the controller does not respond to its own slave address. However, the two-wire bus is still monitored and address recognition may be resumed at any time by setting SSAA. This means that the SSAA bit may be used to temporarily isolate the controller from the two-wire bus. 139 4109C-8051-03/02 Slave Transmitter Mode In the slave transmitter mode, a number of data bytes are transmitted to a master receiver (see Figure 78). Data transfer is initialized as in the slave receiver mode. When SSADR and SSCON have been initialized, the controller waits until it is addressed by its own slave address followed by the data direction bit which must be logic 1 (R) for operating in the slave transmitter mode. After its own slave address and the R bit have been received, the serial interrupt flag is set and a valid status code can be read from SSSTA. This status code is used to vector to an interrupt service routine, and the appropriate action to be taken for each of these status code is detailed in Table 123. The slave transmitter mode may also be entered if arbitration is lost while the controller is in the master mode (see state B0h). If the SSAA bit is reset during a transfer, the controller will transmit the last byte of the transfer and enter state C0h or C8h. The controller is switched to the not addressed slave mode and will ignore the master receiver if it continues the transfer. Thus the master receiver receives all 1's as serial data. While SSAA is reset, the controller does not respond to its own slave address. However, the two-wire bus is still monitored and address recognition may be resumed at any time by setting SSAA. This means that the SSAA bit may be used to temporarily isolate the controller from the two-wire bus. Miscellaneous States There are two SSSTA codes that do not correspond to a define two-wire hardware state (see Table 78). These are discussed hereafter. Status F8h indicates that no relevant information is available because the serial interrupt flag is not yet set. This occurs between other states and when the controller is not involved in a serial transfer. Status 00h indicates that a bus error has occurred during a serial transfer. A bus error is caused when a START or a STOP condition occurs at an illegal position in the format frame. Examples of such illegal positions are during the serial transfer of an address byte, a data byte, or an acknowledge bit. When a bus error occurs, SSI is set. To recover from a bus error, the SSSTO flag must be set and SSI must be cleared. This causes the controller to enter the not addressed slave mode and to clear the SSSTO flag (no other bits in S1CON are affected). The SDA and SCL lines are released and no STOP condition is transmitted. Note: 140 The two-wire controller interfaces to the external two-wire bus via two port 1 pins: P1.6/SCL (serial clock line) and P1.7/SDA (serial data line). To avoid low level asserting and conflict on these lines when the two-wire controller is enabled, the output latches of P1.6 and P1.7 must be set to logic 1. AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Figure 75. Format and States in the Master Transmitter Mode MT Successful transmission to a slave receiver S SLA W A 08h Data 18h A P 28h Next transfer started with a repeated start condition S SLA W 10h R Not acknowledge received after the slave address A P MR 20h Not acknowledge received after a data byte A P 30h Arbitration lost in slave address or data byte A or A Other master continues 38h Arbitration lost and addressed as slave A From slave to master Data nnh Other master continues 38h Other master continues 68h 78h B0h From master to slave A or A A To corresponding states in slave mode Any number of data bytes and their associated acknowledge bits This number (contained in SSSTA) corresponds to a defined state of the two-wire bus 141 4109C-8051-03/02 Figure 76. Format and States in the Master Receiver Mode MR Successful reception from a slave transmitter S SLA 08h R A Data A 40h 50h Data A P 58h Next transfer started with a repeated start condition S SLA R 10h W Not acknowledge received after the slave address A P MT 48h Arbitration lost in slave address or data byte A or A Other master continues 38h Arbitration lost and addressed as slave A From slave to master 142 Data nnh Other master continues 38h Other master continues 68h 78h B0h From master to slave A A To corresponding states in slave mode Any number of data bytes and their associated acknowledge bits This number (contained in SSSTA) corresponds to a defined state of the two-wire bus AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Figure 77. Format and States in the Slave Receiver Mode Reception of the own slave address and one or more data bytes. All are acknowledged S SLA W A Data 60h A Data 80h Last data byte received is not acknowledged A P or S 80h A0h A P or S 88h Arbitration lost as master and addressed as slave A 68h Reception of the general call address and one or more data bytes General Call A Data 70h Last data byte received is not acknowledged A 90h Data A P or S 90h A0h A P or S 98h Arbitration lost as master and addressed as slave by general call A 78h From master to slave From slave to master Data nnh A Any number of data bytes and their associated acknowledge bits This number (contained in SSSTA) corresponds to a defined state of the two-wire bus 143 4109C-8051-03/02 Figure 78. Format and States in the Slave Transmitter Mode Reception of the own slave address and transmission of one or more data bytes. S SLA R A Data A8h Arbitration lost as master and addressed as slave A B8h Data A P or S C0h A B0h Last data byte transmitted. Switched to not addressed slave (SSAA = 0). A All 1's P or S C8h From master to slave From slave to master 144 Data nnh A Any number of data bytes and their associated acknowledge bits This number (contained in SSSTA) corresponds to a defined state of the two-wire bus AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 119. Status for Master Transmitter Mode Application software response Status Code SSSTA Status of the Twowire Bus and Twowire Hardware To SSCON To/From SSDAT SSSTA SSSTO SSI SSAA Next Action Taken by Two-wire Hardware 08h A START condition has Write SLA+W been transmitted X 0 0 X Write SLA+W X 0 0 X 10h A repeated START condition has been transmitted Write SLA+R X 0 0 X Write data byte 0 0 0 X No SSDAT action 1 0 0 X No SSDAT action 0 1 0 X STOP condition will be transmitted and SSSTO flag will be reset. No SSDAT action 1 1 0 X STOP condition followed by a START condition will be transmitted and SSSTO flag will be reset. Write data byte 0 0 0 X No SSDAT action 1 0 0 X No SSDAT action 0 1 0 X STOP condition will be transmitted and SSSTO flag will be reset. No SSDAT action 1 1 0 X STOP condition followed by a START condition will be transmitted and SSSTO flag will be reset. Write data byte 0 0 0 X No SSDAT action 1 0 0 X No SSDAT action 0 1 0 X STOP condition will be transmitted and SSSTO flag will be reset. No SSDAT action 1 1 0 X STOP condition followed by a START condition will be transmitted and SSSTO flag will be reset. Write data byte 0 0 0 X No SSDAT action 1 0 0 X No SSDAT action 0 1 0 X STOP condition will be transmitted and SSSTO flag will be reset. No SSDAT action 1 1 0 X STOP condition followed by a START condition will be transmitted and SSSTO flag will be reset. No SSDAT action 0 0 0 X Two-wire bus will be released and not addressed slave mode will be entered. No SSDAT action 1 0 0 X A START condition will be transmitted when the bus becomes free. 18h 20h 28h 30h 38h SLA+W has been transmitted; ACK has been received SLA+W has been transmitted; NOT ACK has been received Data byte has been transmitted; ACK has been received Data byte has been transmitted; NOT ACK has been received Arbitration lost in SLA+W or data bytes SLA+W will be transmitted. SLA+W will be transmitted. SLA+R will be transmitted. Logic will switch to master receiver mode Data byte will be transmitted. Repeated START will be transmitted. Data byte will be transmitted. Repeated START will be transmitted. Data byte will be transmitted. Repeated START will be transmitted. Data byte will be transmitted. Repeated START will be transmitted. 145 4109C-8051-03/02 Table 120. Status for Master Receiver Mode Application software response Status Code SSSTA Status of the Twowire Bus and Twowire Hardware To SSCON To/From SSDAT SSSTA SSSTO SSI SSAA Next Action Taken by Two-wire Hardware 08h A START condition has Write SLA+R been transmitted X 0 0 X Write SLA+R X 0 0 X 10h A repeated START condition has been transmitted Write SLA+W X 0 0 X SLA+W will be transmitted. Logic will switch to master transmitter mode. Arbitration lost in SLA+R or NOT ACK bit No SSDAT action 0 0 0 X Two-wire bus will be released and not addressed slave mode will be entered. No SSDAT action 1 0 0 X A START condition will be transmitted when the bus becomes free. SLA+R has been transmitted; ACK has been received No SSDAT action 0 0 0 0 Data byte will be received and NOT ACK will be returned. No SSDAT action 0 0 0 1 Data byte will be received and ACK will be returned. No SSDAT action 1 0 0 X No SSDAT action 0 1 0 X STOP condition will be transmitted and SSSTO flag will be reset. No SSDAT action 1 1 0 X STOP condition followed by a START condition will be transmitted and SSSTO flag will be reset. Read data byte 0 0 0 0 Data byte will be received and NOT ACK will be returned. Read data byte 0 0 0 1 Data byte will be received and ACK will be returned. Read data byte 1 0 0 X Read data byte 0 1 0 X STOP condition will be transmitted and SSSTO flag will be reset. Read data byte 1 1 0 X STOP condition followed by a START condition will be transmitted and SSSTO flag will be reset. 38h 40h 48h 50h 58h 146 SLA+R has been transmitted; NOT ACK has been received Data byte has been received; ACK has been returned Data byte has been received; NOT ACK has been returned SLA+R will be transmitted. SLA+R will be transmitted. Repeated START will be transmitted. Repeated START will be transmitted. AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 121. Status for Slave Receiver Mode with Own Slave Address Application software response Status Code SSSTA 60h 68h 80h 88h A0h Status of the Twowire Bus and Twowire Hardware To SSCON To/From SSDAT SSSTA SSSTO SSI SSAA X 0 0 0 Data byte will be received and NOT ACK will be returned. X 0 0 1 Data byte will be received and ACK will be returned. No SSDAT action X 0 0 0 Data byte will be received and NOT ACK will be returned. No SSDAT action X 0 0 1 Data byte will be received and ACK will be returned. Read data byte X 0 0 0 Data byte will be received and NOT ACK will be returned. Read data byte X 0 0 1 Data byte will be received and ACK will be returned. Own SLA+W has been No SSDAT action received; ACK has been returned No SSDAT action Arbitration lost in SLA+R/W as master; own SLA+W has been received; ACK has been returned Previously addressed with own SLA+W; data has been received; ACK has been returned Previously addressed with own SLA+W; data has been received; NOT ACK has been returned A STOP condition or repeated START condition has been received while still addressed as slave Read data byte 0 0 0 0 Read data byte 0 0 0 1 Read data byte 1 0 0 0 Read data byte 1 0 0 1 No SSDAT action 0 0 0 0 No SSDAT action 0 0 0 1 No SSDAT action No SSDAT action 1 1 0 0 0 0 0 1 Next Action Taken by Two-wire Hardware Switched to the not addressed slave mode; no recognition of own SLA or GCA. Switched to the not addressed slave mode; own SLA will be recognized; GCA will be recognized if SSGC = logic 1. Switched to the not addressed slave mode; no recognition of own SLA or GCA. A START condition will be transmitted when the bus becomes free. Switched to the not addressed slave mode; own SLA will be recognized; GCA will be recognized if SSGC = logic 1. A START condition will be transmitted when the bus becomes free. Switched to the not addressed slave mode; no recognition of own SLA or GCA. Switched to the not addressed slave mode; own SLA will be recognized; GCA will be recognized if SSGC = logic 1. Switched to the not addressed slave mode; no recognition of own SLA or GCA. A START condition will be transmitted when the bus becomes free. Switched to the not addressed slave mode; own SLA will be recognized; GCA will be recognized if SSGC = logic 1. A START condition will be transmitted when the bus becomes free. 147 4109C-8051-03/02 Table 122. Status for Slave Receiver Mode with General Call Address Application software response Status Code SSSTA Status of the Twowire Bus and Twowire Hardware 70h General call address has been received; ACK has been returned 78h 90h 98h Arbitration lost in SLA+R/W as master; general call address has been received; ACK has been returned Previously addressed with general call; data has been received; ACK has been returned Previously addressed with general call; data has been received; NOT ACK has been returned To SSCON To/From SSDAT SSSTA SSSTO SSI SSAA No SSDAT action X 0 0 0 Data byte will be received and NOT ACK will be returned. No SSDAT action X 0 0 1 Data byte will be received and ACK will be returned. No SSDAT action X 0 0 0 Data byte will be received and NOT ACK will be returned. No SSDAT action X 0 0 1 Data byte will be received and ACK will be returned. Read data byte X 0 0 0 Data byte will be received and NOT ACK will be returned. Read data byte X 0 0 1 Data byte will be received and ACK will be returned. Read data byte 0 0 0 0 Read data byte 0 0 0 1 Read data byte Read data byte A0h 148 A STOP condition or repeated START condition has been received while still addressed as slave 1 1 0 0 0 0 0 1 No SSDAT action 0 0 0 0 No SSDAT action 0 0 0 1 No SSDAT action 1 0 0 0 No SSDAT action 1 0 0 1 Next Action Taken by Two-wire Hardware Switched to the not addressed slave mode; no recognition of own SLA or GCA. Switched to the not addressed slave mode; own SLA will be recognized; GCA will be recognized if SSGC = logic 1. Switched to the not addressed slave mode; no recognition of own SLA or GCA. A START condition will be transmitted when the bus becomes free. Switched to the not addressed slave mode; own SLA will be recognized; GCA will be recognized if SSGC = logic 1. A START condition will be transmitted when the bus becomes free. Switched to the not addressed slave mode; no recognition of own SLA or GCA. Switched to the not addressed slave mode; own SLA will be recognized; GCA will be recognized if SSGC = logic 1. Switched to the not addressed slave mode; no recognition of own SLA or GCA. A START condition will be transmitted when the bus becomes free. Switched to the not addressed slave mode; own SLA will be recognized; GCA will be recognized if SSGC = logic 1. A START condition will be transmitted when the bus becomes free. AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 123. Status for Slave Transmitter Mode Status Code SSSTA A8h B0h B8h C0h Status of the Twowire Bus and Twowire Hardware Application software response To SSCON To/From SSDAT Own SLA+R has been received; ACK has been returned Arbitration lost in SLA+R/W as master; own SLA+R has been received; ACK has been returned Data byte in SSDAT has been transmitted; ACK has been received Data byte in SSDAT has been transmitted; NOT ACK has been received SSSTA SSSTO SSI SSAA Write data byte X 0 0 0 Last data byte will be transmitted. Write data byte X 0 0 1 Data byte will be transmitted. Write data byte X 0 0 0 Last data byte will be transmitted. Write data byte X 0 0 1 Data byte will be transmitted. Write data byte X 0 0 0 Last data byte will be transmitted. Write data byte X 0 0 1 Data byte will be transmitted. No SSDAT action 0 0 0 0 No SSDAT action 0 0 0 1 No SSDAT action No SSDAT action C8h Last data byte in SSDAT has been transmitted (SSAA= 0); ACK has been received 1 1 0 0 0 0 0 1 No SSDAT action 0 0 0 0 No SSDAT action 0 0 0 1 No SSDAT action 1 0 0 0 No SSDAT action 1 0 0 1 SSI SSAA Next Action Taken by Two-wire Hardware Switched to the not addressed slave mode; no recognition of own SLA or GCA. Switched to the not addressed slave mode; own SLA will be recognized; GCA will be recognized if SSGC = logic 1. Switched to the not addressed slave mode; no recognition of own SLA or GCA. A START condition will be transmitted when the bus becomes free. Switched to the not addressed slave mode; own SLA will be recognized; GCA will be recognized if SSGC = logic 1. A START condition will be transmitted when the bus becomes free. Switched to the not addressed slave mode; no recognition of own SLA or GCA. Switched to the not addressed slave mode; own SLA will be recognized; GCA will be recognized if SSGC = logic 1. Switched to the not addressed slave mode; no recognition of own SLA or GCA. A START condition will be transmitted when the bus becomes free. Switched to the not addressed slave mode; own SLA will be recognized; GCA will be recognized if SSGC = logic 1. A START condition will be transmitted when the bus becomes free. Table 124. Status for Miscellaneous States Application software response Status Code SSSTA Status of the Twowire Bus and Twowire Hardware To SSCON To/From SSDAT F8h No relevant state information available; SSI = 0 00h Bus error due to an illegal START or STOP No SSDAT action condition SSSTA No SSDAT action SSSTO No SSCON action 0 1 0 Next Action Taken by Two-wire Hardware Wait or proceed current transfer. X Only the internal hardware is affected, no STOP condition is sent on the bus. In all cases, the bus is released and SSSTO is reset. 149 4109C-8051-03/02 Registers Table 125. SSCON Register SSCON (S:93h) - Synchronous Serial Control Register 7 6 5 4 3 2 1 0 SSCR2 SSPE SSSTA SSSTO SSI SSAA SSCR1 SSCR0 Bit Number Bit Mnemonic Description Synchronous Serial Control Rate Bit 2 Refer to Table for rate description. 7 SSCR2 6 SSPE Synchronous Serial Peripheral Enable Bit Set to enable the controller. Clear to disable the controller. 5 SSSTA Synchronous Serial Start Flag Set to send a START condition on the bus. Clear not to send a START condition on the bus. 4 SSSTO Synchronous Serial Stop Flag Set to send a STOP condition on the bus. Clear not to send a STOP condition on the bus. 3 SSI Synchronous Serial Interrupt Flag Set by hardware when a serial interrupt is requested. Must be cleared by software to acknowledge interrupt. Synchronous Serial Assert Acknowledge Flag Set to enable slave modes. Slave modes are entered when SLA or GCA (if SSGC set) is recognized. Clear to disable slave modes. Master Receiver Mode in progress Clear to force a not acknowledge (high level on SDA). Set to force an acknowledge (low level on SDA). Master Transmitter Mode in progress This bit has no specific effect when in master transmitter mode. Slave Receiver Mode in progress Clear to force a not acknowledge (high level on SDA). Set to force an acknowledge (low level on SDA). Slave Transmitter Mode in progress Clear to isolate slave from the bus after last data byte transmission. Set to enable slave mode. 2 SSAA 1 SSCR1 Synchronous Serial Control Rate Bit 1 Refer to Table for rate description. 0 SSCR0 Synchronous Serial Control Rate Bit 0 Refer to Table for rate description. Reset Value = 0000 0000b 150 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Table 126. SSSTA Register SSSTA (S:94h) - Synchronous Serial Status Register 7 6 5 4 3 2 1 0 SSC4 SSC3 SSC2 SSC1 SSC0 0 0 0 Bit Number Bit Mnemonic Description 7:3 SSC4:0 2:0 0 Synchronous Serial Status Code Bits 0 to 4 Refer to Table 119 to Table 78 for status description. Always 0. Reset Value = F8h Table 127. SSDAT Register SSDAT (S:95h) - Synchronous Serial Data Register 7 6 5 4 3 2 1 0 SSD7 SSD6 SSD5 SSD4 SSD3 SSD2 SSD1 SSD0 Bit Number Bit Mnemonic Description 7:1 SSD7:1 Synchronous Serial Address bits 7 to 1 or Synchronous Serial Data Bits 7 to 1 0 SSD0 Synchronous Serial Address bit 0 (R/W) or Synchronous Serial Data Bit 0 Reset Value = 1111 1111b Table 128. SSADR Register SSADR (S:96h) - Synchronous Serial Address Register 7 6 5 4 3 2 1 0 SSA7 SSA6 SSA5 SSA4 SSA3 SSA2 SSA1 SSGC Bit Number Bit Mnemonic Description 7:1 SSA7:1 Synchronous Serial Slave Address Bits 7 to 1. 0 SSGC Synchronous Serial General Call Bit Set to enable the general call address recognition. Clear to disable the general call address recognition. Reset Value = 1111 1110b 151 4109C-8051-03/02 Analog to Digital Converter The AT8xC51SND1A implements a 2-channel 10-bit (8 true bits) analog to digital converter (ADC). First channel of this ADC can be used for battery monitoring while the second one can be used for voice sampling at 8 kHz. Description The A/D converter interfaces with the C51 core through four special function registers: ADCON, the ADC control register (see Table 130); ADDH and ADDL, the ADC data registers (see Table 132 and Table 133); and ADCLK, the ADC clock register (see Table 131). As shown in Figure 79, the ADC is composed of a 10-bit cascaded potentiometric digital to analog converter, connected to the negative input of a comparator. The output voltage of this DAC is compared to the analog voltage stored in the Sample and Hold and coming from AIN0 or AIN1 input depending on the channel selected (see Table 129). Figure 79. ADC Structure ADCON.5 ADCON.3 ADEN ADSST ADC Interrupt Request ADCON.4 ADEOC ADC CLOCK CONTROL EADC IEN1.3 AIN1 0 AIN0 1 8 ADDH 2 ADDL + SAR AVSS ADCS Sample and Hold 10 ADCON.0 R/2R DAC AREFP AREFN Figure 80 shows the timing diagram of a complete conversion. For simplicity, the figure depicts the waveforms in idealized form and do not provide precise timing information. For ADC characteristics and timing parameters refer to the Section "AC Characteristics" of the AT8xC51SND1A datasheet. Figure 80. Timing Diagram CLK TADCLK ADEN TSETUP ADSST TCONV ADEOC 152 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Clock Generation The ADC clock is generated by division of the peripheral clock (see details in Section "X2 Feature", page 4). The division factor is then given by ADCP4:0 bits in ADCLK register. Figure 39 shows the ADC clock generator and its calculation formula(1). Figure 39. ADC Clock Generator and Symbol Caution: ADCLK PER CLOCK /2 ADCD4:0 ADC CLOCK ADC Clock ADC Clock Symbol PERclk ADCclk = ------------------------2 ADCD Note: Channel Selection In all cases, the ADC clock frequency may be higher than the maximum FADCLK parameter reported in the Section "AC Characteristics" of the AT8xC51SND1A datasheet. The channel on which conversion is performed is selected by the ADCS bit in ADCON register according to Table 129. Table 129. ADC Channel Selection Conversion Precision Channel 0 AIN1 1 AIN0 The 10-bit precision conversion is achieved by stopping the CPU core activity during conversion for limiting the digital noise induced by the core. This mode called the Pseudo-Idle mode(1), (2) is enabled by setting the ADIDL bit in ADCON register. Thus, when conversion is launched (see Section "Conversion Launching", page 154), the CPU core is stopped until the end of the conversion (see Section "End Of Conversion", page 154). This bit is cleared by hardware at the end of the conversion. Notes: Configuration ADCS 1. Only the CPU activity is frozen, peripherals are not affected by the Pseudo-Idle mode. 2. If some interrupts occur during the Pseudo-Idle mode, they will be delayed and processed, according to their priority after the end of the conversion. The ADC configuration consists in programming the ADC clock as detailed in the Section "Clock Generation", page 153. The ADC is enabled using the ADEN bit in ADCON register. As shown in Figure 93, user must wait the setup time (TSETUP) before launching any conversion. 153 4109C-8051-03/02 Figure 40. ADC Configuration Flow ADC Configuration Program ADC Clock ADCD4:0 = xxxxxb Enable ADC ADIDL = x ADEN = 1 Wait Setup time Conversion Launching The conversion is launched by setting the ADSST bit in ADCON register, this bit remains set during the conversion. As soon as the conversion is started, it takes 11 clock periods (TCONV) before the data is available in ADDH and ADDL registers. Figure 41. ADC Conversion Launching Flow ADC Conversion Start Select Channel ADCS = 0-1 Start Conversion ADSST = 1 End Of Conversion 154 The end of conversion is signalled to you by the ADEOC flag in ADCON register becoming set or by the ADSST bit in ADCON register becoming cleared. ADEOC flag can generate an interrupt if enabled by setting EADC bit in IEN1 register. This flag is set by hardware and must be reset by software. AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Registers Table 130. ADCON Register ADCON (S:F3h) - ADC Control Register 7 6 5 4 3 2 1 0 - ADIDL ADEN ADEOC ADSST - - ADCS Bit Number Bit Mnemonic Description Reserved The value read from this bit is always 0. Do not set this bit. 7 - 6 ADIDL ADC Pseudo-Idle Mode Set to suspend the CPU core activity (pseudo-idle mode) during conversion. Clear by hardware at the end of conversion. 5 ADEN ADC Enable Bit Set to enable the A to D converter. Clear to disable the A to D converter and put it in low power stand-by mode. 4 ADEOC End Of Conversion Flag Set by hardware when ADC result is ready to be read. This flag can generate an interrupt. Must be cleared by software. 3 ADSST Start and Status Bit Set to start an A to D conversion on the selected channel. Cleared by hardware at the end of conversion. 2-1 - 0 ADCS Reserved The value read from these bits is always 0. Do not set these bits. Channel Selection Bit Set to select channel 0 for conversion. Clear to select channel 1 for conversion. Reset Value = 0000 0000b Table 131. ADCLK Register ADCLK (S:F2h) - ADC Clock Divider Register 7 6 5 4 3 2 1 0 - - - ADCD4 ADCD3 ADCD2 ADCD1 ADCD0 Bit Number Bit Mnemonic Description 7-5 - 4-0 ADCD4:0 Reserved The value read from these bits is always 0. Do not set these bits. ADC Clock Divider 5-bit divider for ADC clock generation. 155 4109C-8051-03/02 Table 132. ADDH Register ADDH (S:F5h Read Only) - ADC Data High Byte Register 7 6 5 4 3 2 1 0 ADAT9 ADAT8 ADAT7 ADAT6 ADAT5 ADAT4 ADAT3 ADAT2 Bit Number 7-0 Bit Mnemonic Description ADAT9:2 ADC Data Eight Most Significant Bits of the 10-bit ADC data. Reset Value = 0000 0000b Table 133. ADDL Register ADDL (S:F4h Read Only) - ADC Data Low Byte Register 7 6 5 4 3 2 1 0 - - - - - - ADAT1 ADAT0 Bit Number Bit Mnemonic Description 7-2 - 1-0 ADAT1:0 Reserved The value read from these bits is always 0. Do not set these bits. ADC Data Two Least Significant Bits of the 10-bit ADC data. Reset Value = 0000 0000b 156 AT8xC51SND1A 4109C-8051-03/02 AT8xC51SND1A Keyboard Interface The AT8xC51SND1A implements a keyboard interface allowing the connection of a 4 x n matrix keyboard. It is based on 4 inputs with programmable interrupt capability on both high or low level. These inputs are available as alternate function of P1.3:0 and allow exit from idle and power down modes. Description The keyboard interface interfaces with the C51 core through two special function registers: KBCON, the keyboard control register (see Table 134); and KBSTA, the keyboard control and status register (see Table 135). The keyboard inputs are considered as 4 independent interrupt sources sharing the same interrupt vector. An interrupt enable bit (EKB in IEN1 register) allows global enable or disable of the keyboard interrupt (see Figure 42). As detailed in Figure 43 each keyboard input has the capability to detect a programmable level according to KINL3:0 bit value in KBCON register. Level detection is then reported in interrupt flags KINF3:0 in KBSTA register. A keyboard interrupt is requested each time one of the four flags is set, i.e. the input level matches the programmed one. Each of these four flags can be masked by software using KINM3:0 bits in KBCON register and is cleared by reading KBSTA register. This structure allows keyboard arrangement from 1 by n to 4 by n matrix and allow usage of KIN inputs for any other purposes. Figure 42. Keyboard Interface Block Diagram KIN0 Input Circuitry KIN1 Input Circuitry KIN2 Input Circuitry KIN3 Input Circuitry Keyboard Interface Interrupt Request EKB IEN1.4 Figure 43. Keyboard Input Circuitry 0 KIN3:0 KINF3:0 1 KBSTA.3:0 KINM3:0 KINL3:0 KBCON.3:0 KBCON.7:4 Power Reduction Mode KIN3:0 inputs allow exit from idle and power down modes as detailed in Section "Power Management", page 41. To enable this feature, KPDE bit in KBSTA register must be set to logic 1. Due to the asynchronous keypad detection in power down mode (all clocks are stopped), exit may happen on parasitic key press. In this case, no key is detected and software must enter power down again. 157 4109C-8051-03/02 Registers Table 134. KBCON Register KBCON (S:A3h) - Keyboard Control Register 7 6 5 4 3 2 1 0 KINL3 KINL2 KINL1 KINL0 KINM3 KINM2 KINM1 KINM0 Bit Number Bit Mnemonic Description 7-4 KINL3:0 Keyboard Input Level Bit Set to enable a high level detection on the respective KIN3:0 input. Clear to enable a low level detection on the respective KIN3:0 input. 3-0 KINM3:0 Keyboard Input Mask Bit Set to prevent the respective KINF3:0 flag from generating a keyboard interrupt. Clear to allow the respective KINF3:0 flag to generate a keyboard interrupt. Reset Value = 0000 1111b Table 135. KBSTA Register KBSTA (S:A4h) - Keyboard Control and Status Register 7 6 5 4 3 2 1 0 KPDE - - - KINF3 KINF2 KINF1 KINF0 Bit Number Bit Mnemonic Description 7 KPDE 6-4 - 3-0 KINF3:0 Keyboard Power Down Enable Bit Set to enable exit of power down mode by the keyboard interrupt. Clear to disable exit of power down mode by the keyboard interrupt. Reserved The value read from these bits is always 0. Do not set these bits. Keyboard Input Interrupt Flag Set by hardware when the respective KIN3:0 input detects a programmed level. Cleared when reading KBSTA. Reset Value = 0000 0000b 158 AT8xC51SND1A 4109C-8051-03/02 Table of Contents Table of Contents Features ................................................................................................. 1 Description............................................................................................. 1 Typical Applications ............................................................................. 2 Block Diagram ....................................................................................... 3 Clock Controller .................................................................................... 4 Oscillator ............................................................................................................... 4 X2 Feature ............................................................................................................ 4 PLL........................................................................................................................ 5 Registers............................................................................................................... 7 Program/Code Memory ....................................................................... 10 ROM Memory Architecture ................................................................................. 10 Flash Memory Architecture ................................................................................. 11 Hardware Security System ................................................................................. 12 Boot Memory Execution ...................................................................................... 12 Registers............................................................................................................. 14 Hardware Bytes .................................................................................................. 15 Data Memory ........................................................................................ 17 Internal Space ..................................................................................................... 17 External Space.................................................................................................... 19 Dual Data Pointer................................................................................................ 21 Registers............................................................................................................. 22 Special Function Registers ................................................................ 24 Interrupt System.................................................................................. 31 Interrupt System Priorities................................................................................... 31 External Interrupts............................................................................................... 34 Registers............................................................................................................. 35 Power Management............................................................................. 41 Reset................................................................................................................... 41 Reset Recommendation to Prevent Flash Corruption ........................................ 41 Idle Mode ............................................................................................................ 42 Power-down Mode .............................................................................................. 42 Registers............................................................................................................. 44 i Timers/Counters ................................................................................. 45 Timer/Counter Operations .................................................................................. Timer Clock Controller........................................................................................ Timer 0 ............................................................................................................... Timer 1 ............................................................................................................... Interrupt .............................................................................................................. Registers ............................................................................................................ 45 45 46 48 49 50 Watchdog Timer.................................................................................. 53 Description.......................................................................................................... Watchdog Clock Controller................................................................................. Watchdog Operation........................................................................................... Registers ............................................................................................................ 53 53 54 55 MP3 Decoder ....................................................................................... 56 Decoder .............................................................................................................. Audio Controls .................................................................................................... Decoding Errors.................................................................................................. Frame Information .............................................................................................. Ancillary Data ..................................................................................................... Interrupt .............................................................................................................. Registers ............................................................................................................ 56 58 59 59 59 60 62 Audio Output Interface....................................................................... 67 Description.......................................................................................................... Clock Generator ................................................................................................. Data Converter ................................................................................................... Audio Buffer........................................................................................................ MP3 Buffer.......................................................................................................... Interrupt Request................................................................................................ MP3 Song Playing .............................................................................................. Voice or Sound Playing ...................................................................................... Registers ............................................................................................................ 67 68 68 69 70 70 70 71 72 Universal Serial Bus ........................................................................... 74 Description.......................................................................................................... 75 USB Interrupt System......................................................................................... 77 Registers ............................................................................................................ 79 MultiMediaCard Controller................................................................. 88 Card Concept ..................................................................................................... Bus Concept ....................................................................................................... Description.......................................................................................................... Clock Generator ................................................................................................. Command Line Controller................................................................................... Data Line Controller............................................................................................ ii 88 88 93 93 95 97 Table of Contents Interrupt............................................................................................................. 103 Registers........................................................................................................... 104 IDE/ATAPI Interface........................................................................... 110 Description ........................................................................................................ 110 Registers........................................................................................................... 112 Serial I/O Port..................................................................................... 113 Mode Selection ................................................................................................. 113 Baud Rate Generator........................................................................................ 113 Synchronous Mode (Mode 0)............................................................................ 114 Asynchronous Modes (Modes 1, 2 and 3) ........................................................ 116 Multiprocessor Communication (Modes 2 and 3) ............................................. 119 Automatic Address Recognition ........................................................................ 119 Interrupt............................................................................................................. 121 Registers........................................................................................................... 122 Synchronous Peripheral Interface ................................................... 125 Description ........................................................................................................ 126 Interrupt............................................................................................................. 129 Configuration..................................................................................................... 130 Registers........................................................................................................... 134 Two-wire Controller........................................................................... 136 Description ........................................................................................................ 136 Registers........................................................................................................... 150 Analog to Digital Converter.............................................................. 152 Description ........................................................................................................ 152 Registers........................................................................................................... 155 Keyboard Interface ............................................................................ 157 Description ........................................................................................................ 157 Registers........................................................................................................... 158 iii Atmel Headquarters Atmel Operations Corporate Headquarters Memory 2325 Orchard Parkway San Jose, CA 95131 TEL 1(408) 441-0311 FAX 1(408) 487-2600 Europe Atmel Sarl Route des Arsenaux 41 Case Postale 80 CH-1705 Fribourg Switzerland TEL (41) 26-426-5555 FAX (41) 26-426-5500 Asia Atmel Asia, Ltd. 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The Company assumes no responsibility for any errors which may appear in this document, reserves the right to change devices or specifications detailed herein at any time without notice, and does not make any commitment to update the information contained herein. No licenses to patents or other intellectual property of Atmel are granted by the Company in connection with the sale of Atmel products, expressly or by implication. Atmel's products are not authorized for use as critical components in life support devices or systems. Atmel(R), MultiMediaCardTM , SmartMedia(R) and DataFlash(R) are trademarks and/or registered trademarks of Atmel Corporation. Other terms and product names may be the trademarks of others. Printed on recycled paper. 4109C-8051-03/02 /xM