S-W MANUAL - Wolfson Microelectronics Co., Ltd.

WM8816 Micro-Contr ol ler Board User Handbook

November 2000, Rev 1.0

WOLFSON MICROELECTRONICS LTD

Lutton Court, Bernard Terrace, Edinburgh, EH8 9NX, UK

Tel: +44 (0) 131 667 9386

Fax: +44 (0) 131 667 5176

Email: sales@wolfson.co.uk

http://www.wolfson.co.uk

The Applications information contained

herein is provided for informat i on onl y.

Wolfson makes no warranties with respect

to the inf ormation cont ai ned herei n.

2000 Wolfson Microelectronics Ltd.

INTRODUCTION

The WM8816 Micro-Controller Board is a user-friendly int erface for the WM8816 Stereo Vol ume

Control Evaluat i on Platform .

By connecting the WM8816 Micro-Controller Board direc tly to the 10 pin header of the WM8816

evaluation board us ers can quickly and easily generate the digit a l signals required to demonstrate

the volume, balance and peak level detection features of the WM8816 volume control chip.

This evaluat i on board should be used in conjunc tion with:

• The latest revi sion of the WM8816 datasheet

• The WM8816_EV1B Board

The datasheet offers device f unctionality information as well as timing and data f ormat requirem ents.

GETTING STARTED

PACKING LIST

The WM8816 Micro-Controller Board Ki t contains:

• 1 WM8816_MICRO_EV1B Micro-Control l er Board

• This manual -1 W M8816_MICRO_EV1M

• 10 Pin Ribbon Cable For Connec tion To The W M8816_EV1B Board

CUSTOMER REQUI REMENTS

Minimum customer requirements are:

• A 9 Volt D.C. Bench Top Power Supply.

• A WM8816_EV1B Board

WM8816_MICRO_EV1M

WOLFSON MICROELECTRONICS LTD Rev 1.0 November 2000

BLOCK DIAGRAM

Figure 1 W M8816 Micro-Control l er Board Bl ock Di agram

POWER SUPPLI ES

A 9 Volt power supply, with a posi t i ve centre pin mini at ure power jac k, should be connec ted to the

power input connect or (J3). This 9 Volt supply is regulated onboard t o t he 5 Volt supply required by

the PIC Micro-Controller (U7).

For normal operation the power on/off switc h (S W1) shoul d be i n t he ri ght hand (on) position,

illuminating the “Power On” LED (D10).

BOARD FUNCTIONALITY

Header J5 of the WM8816 Micro-Control l e r B oard should be connected directly to the 10-pin header

of the WM8816 Evaluation B oard using the ribbon cable provi ded.

The keypad (K1) all ows f or t he i nput of Volum e, Balance, and Peak Level i nf ormation which is t hen

sent, vi a t he ri bbon cable, to the E valuation Board. A PIC Micro-Controller is used to convert user

inputs, from the keypad, into the appropriate digital format (as described in the WM8816 dat a sheet).

Component s U2 & U8 form a f our-di gi t display, which is used to displ ay the current Volume, Balance,

and Peak Reference Register set tings. LED’s D5, D6 and D7 indicate which of the three display

modes i s being currently dis pl ayed.

Key

Wolfson Microelectronics Ltd. – WM8816_Micro_EV1_REV2

PIC 16F874

Micro-Controller

SW1

D10

D4 D2

D3 D1

U2 U8 DISPLAY MODE

Volume

Balance

Peak Ref.

Mute

Left O/L Ri ght O/L

Left OK Right OK

PEAK STAT. REG

J4 J2

Power

6-CHANNEL

Front

Rear

Centre

LFE

D13

D12

D11

D15

Front Rear Centre / LFE

WM8816_MICRO_EV1M

WOLFSON MICROELECTRONICS LTD Rev 1.0 November 2000

KEYPAD LAYOUT

Figure 2 Keypad Layout

The following sec tion describes the function of each of these keys -

SETTING THE VOLUME

The volume i s set using t he up and down arrow keys marked “Vol.”. The up arrow increments t he

volume i n 0.5dB steps whilst the down arrow decrement s the volume in 0.5dB steps. The appl i ed

gain can be varied bet ween +15.5dB and –111. 5dB. Holding the keys down causes the output

volume l evel to be changed faster.

When either of the “Vol.” keys are pressed, LED (D7) is illuminated, and the output display (U2 & U8)

is updated t o show the lates t volume, in dB .

ADJUSTING THE BALANCE SETTING

The left and ri ght arrow keys, marked “Bal.”, are us ed to adjust the relative loudness of each channel.

Attenuating the opposite c hannel makes one c hannel (apparent l y) l ouder.

The left arrow shif ts the balance t owards t he l eft channel in 0.5 dB steps. Similarly the ri ght arrow

key shifts the balanc e t o wards the ri ght channel in 0.5dB steps. Pres sing the “Centre Bal. ” Key

equalises the volume em i tting from both channels.

When any of the balance keys is pressed LED (D6) is illuminated and the output dis play (U2 & U8) is

updated to indicate the lates t setting. Balance setti ngs are displayed as a 3 digi t number preceded

by an ‘L’ or ‘R’. The letter ‘L’ indicates that the left channel i s the loudest channel, whilst the let t er ‘R’

indicat es that the right channel is the loudes t channel. The following num ber i ndi cates how many

dB’s the opposite channel has been attenuated to achieve the balance effec t . For example a display

of R45.5 indicates that the balance is currently set towards the right channel – and that to achieve

this t he l eft channel has been at tenuated by 45.5dB.

Holding down either of the l eft / right balanc e keys causes the settings to change much faster. The

maximum volume di f ference that can be set between channels, in the current board im pl ementation,

is 63.5 dB .

MUTE

Pressing the key m ark ed MUTE causes the mute option to be toggled between on and off. LED (D8)

is illumi nated when the WM8816 is muted.

The WM8816 Micro-Controller Board initiates what the data s heet calls a Sof tware Mute” - since it is

achieved by writing t he code for –112dB to the digit al serial interfac e of the WM8816 chip.

It is s till possible to adjust t he volume, balance and peak level detect ion settings whilst the device is

muted. However it should be not ed t hat these setti ngs will only come into effect onc e t he devic e is

un-muted.

←

BAL.

MUTE

↑

VOL.

CENTRE

BAL.

↓

VOL.

DISP.

→

BAL.

P.REF P.STAT

FRONT

REAR

CENTRE

/LFE

WM8816_MICRO_EV1M

WOLFSON MICROELECTRONICS LTD Rev 1.0 November 2000

USING THE PEAK LEVEL DETECTOR

The WM8816 Datasheet desc ri bes the full functionality of t he peak level detector.

Press i ng the key marked “P.REF.” cyc l es through, on the output di splay (U2 & U8), all t he val ues

which can be written to the Peak Reference Regi ster (0,1,2….255). Once 255 is reached the display

wraps back round to zero. These values are written instantaneously to t he Peak Reference Regis ter.

When the output display (U2 & U8) is showing peak reference inform ation the first l e t ter of the

output display will be a ‘P’ (i.e. P102) and the LED (D5) will be illuminat ed.

In order to read the i nformation s tored in the Peak Status Register the user should press the key

marked “P.STAT”. If the left channel output has exceeded the val ue hel d i n the Peak Reference

held in the Peak Ref erence Register then the LED (D2) will be illum i nat ed. If the left or right channel

outputs have not exceeded the value hel d i n t he Peak Reference Regis ter then the LED’s (D3 & D1)

are illuminat ed as appropriate.

Users s houl d be aware that once the output level has exceeded t he reference level that t he Peak

Status Register will remain set until read (i.e. when the “P.STAT” key is pressed).

Press i ng any key, other than “P.STAT” switches off all the P eak Status output LED’s (D1…D4).

TOGGLING THE DISPL AY MODE

Users c an toggle between the Volume, Balance, and Peak Reference displ ay modes by pressi ng the

key marked “DISP.”. This key cycles through the t hree out put display options , without maki ng any

adjustments to t he current settings.

The three LED’s i n the top right hand corner of the board (D5, D6, and D7) indicat e t he current

display mode. This can al so be deduced from the first letter of the four digi t display (U2 & U8).

Volume displays are prec eded by ei ther a ‘-‘ sign or blank digit , depending on whether attenuation or

gain is being appl i ed. An ‘L’ or ‘R’ precedes Balanc e di splays’ depending on which channel i s

currently louder. Peak Reference di splays are preceded by a ‘P’.

SETTING UP A 6 CHANNEL VOLUME CONTROL

It is possible to use more than one WM8816_EV1B board to ac commodate a multi-channel system.

The sam e DA TA, and CCLK signals can be used for many WM8816’s with different CSB li nes used

to select which chip is currently active.

Figure 6 shows how three WM8816’s can be used with a si ngl e Mic ro-Controller to create a 6

channel volume control.

The three WM8816_EV1B’s should be set up and connec t ed to a ±25V power supply as desc ri bed i n

the “WM8816_EV1BM” user manual. For correct operation it is vital the links on each board are set

up as desc ri bed i n table 1.

The WM8816_EV1B Evaluati on B oard that is being used to control the front stereo pair of speakers

should have a 10 pin ribbon cable from its serial int erface to header J5 on the Mic ro-Controller board,

marked “front”.

Sim i larly the WM8816_EV1B Evaluati on B oard that is being used to control the Rear s tereo pair of

speakers should have a 10 pin ribbon cable from its s eri al interface to header J 4 on the Micro-

Controller board, marked “Rear”.

Finally the WM8816_EV1B Evaluation Board that is controlling the Centre & LFE speakers should

have ribbon connection from the serial interfac e to header J2 on the Micro-Control l er board – marked

“Centre / LFE”. Thi s third WM8816_EV1B is s l i ght l y di f ferent in that it uses its lef t channel to cont rol

the gain applied t o the Centre speaker and it s right channel to c ontrol the gain applied to the LFE.

Input to the three evaluation boards can come from any 6 channel analogue source, say a DVD

player or the WM8736 DAC.

WM8816_MICRO_EV1M

WOLFSON MICROELECTRONICS LTD Rev 1.0 November 2000

Figure 3 Using Three W M8816_EV1B Boards to Create A Six Channel Vol ume Control

WM8816_EV1B LNK1 LNK2 LNK3

Front Closed Open Open

Rear Open Closed Open

Centre / LFE Open Open Clos ed

Table 1 Link Positions For 6 Channel Operation

Rear

Centre / LFE

Front

Centre

LFE

6 Channel Input

WM8736 - 6 Channel DAC

Digital Control Data

From The Micro-Controller

Board

8816 8816 8816

WM8816_MICRO_EV1M

WOLFSON MICROELECTRONICS LTD Rev 1.0 November 2000

USING THE 6 CHANNEL VOLUME CONTROL

The keys marked “Front”, “ Rear” and “Centre / LFE” sel ect which of the three WM8816_EV1B i s

currently active.

When the “Front” key is press ed then the WM8816_EV1B that is c ont rolling the Front Stereo Pair of

speakers is made active. A ny us er input s to the keypad will be applied to this Evaluation Board only.

This is indicated by LED D13 being illuminated.

If the “Rear” key is pressed t hen the second WM8816_EV1B, which controls the Rear Stereo Pair of

speakers, is made act i ve. A ny us er input s to the keypad will now be applied to this Evaluation Board

only. LED D12 will be illuminated

If the “Centre / LFE” key is pressed then the third WM8816_EV1B, which controls the centre and LFE

speakers i s made acti ve. This third WM8816_EV1B dif fers from t he others since t he l eft channel

controls the Centre speaker and t he ri ght channel controls the LFE speaker. It is not a s t ereo pair of

speakers l i ke the front and rear.

Pressi ng the “Centre / LFE” key once al l ows variabl e gain to be applied to the Cent re speaker.

When the centre speaker is under control of t he Mic ro-Cont roller board then LED D11 is illuminated.

Pressi ng the “Centre / LFE” key once more allows the Micro-Cont rol l er board to vary the volume of

the LFE speak er. When t he LFE speaker is current ly s elec ted LED D15 will be illuminated.

Because the Centre and LFE are mono s i gnals balance information can not be writt en to this third

WM8816_EV1B Evaluati on Board. If a user at tempts to use any of the balanc e keys when Centre or

LFE is s el ected then “------“ is output t o the four digit dis p l ay (U2 & U8).

In 6 Channel Mode the peak reference keys operate as before – except for the fact that data is

written to or read from the WM8816_EV1B which is currently active, as indicated by LEDS D13, D12,

D11, D15.

Pressing t he Mute k ey will mute all 6-out put speakers. Pres sing the key again will un-mute all the

channels and restore them t o their original state.

WM8816_MICRO_EV1M

WOLFSON MICROELECTRONICS LTD Rev 1.0 November 2000

KEY FUNCTION SUMMARY

KEY FUNCTION

Increments the output gai n i n 0.5 dB steps

Decrem ent s the output gain in 0.5dB steps

Shift s the Balance towards t he l ef t channel in 0.5

dB steps.

Shift s the Balance towards t he ri ght channel in

0.5 dB steps.

Makes the out put gain from each channel equal.

Mutes the out put of the WM8816 Volume Control

Chip. Pres sing again un-mut es the device.

Cycles through the three output di splay modes

Volum e, Balance and Peak Ref erence.

Sets the Peak Reference Regi ster

Reads the Peak Status Regi ster. LED’s

D1,D2,D3, & D4 used to displa y t he result

Select s the Front speakers as those current l y

under control of the Micro-Controller board.

(6 Channel Mode Only).

Select s the Rear speakers as those currentl y

under control of the Micro-Controller board.

(6 Channel Mode Only).

Select s the Centre & LFE s peakers as those

currently under c ontrol of the Micro-Control l er

board (6 Channel Mode Only).

Table 2 Key Function Summary

←

BAL.

MUTE

↑

VOL.

CENTRE

BAL.

↓

VOL.

DISP.

→

BAL.

P.REF

P.STAT

FRONT

REAR

CENTRE

/ LFE

WM8816_MICRO_EV1M

WOLFSON MICROELECTRONICS LTD Rev 1.0 November 2000

HEADERS/CONNECTORS/SWITCHES

FUNCTION

SW1 Power On / Off Switch

J3 9 Volt P ower Input

J1 PIC Micro-Controller Programming Sock et

J2 For use with a 6-channel system only

(see Setting Up A 6 Channel Volume Control)

J4 For use with a 6-channel system only

Table 3 Miscellaneous Functions

J5 FUNCTION

1Chip Select 1

2GND

3Chip Select 2

4GND

5Chip Select 3

6GND

7Data

8GND

9Cclk

10 GND

Table 4 Digital Serial Interface

WM8816_MICRO_EV1M

WOLFSON MICROELECTRONICS LTD Rev 1.0 November 2000

WM8816_MICRO_EV1_REV2 SCHEMATIC

Figure 4 Top Level View

WM8816_MICRO_EV1M

WOLFSON MICROELECTRONICS LTD Rev 1.0 November 2000

Figure 5 PIC Micro-Controller, LED’ s, Header + Keypad

WM8816_MICRO_EV1M

WOLFSON MICROELECTRONICS LTD Rev 1.0 November 2000

Figure 6 Four Digit Display

Figure 7 Power

WM8816_MICRO_EV1M

WOLFSON MICROELECTRONICS LTD Rev 1.0 November 2000

MICRO_CONTROLLER

A PIC16F874 Mic ro-Controller was used for the WM8816_MICRO_EV1B board. Code was compiled

and programmed using MPASM V5.0. Further details on PIC Micro-Controllers can be found at

www.microchip.com.

The Micro-Controller code is available on reques t .

EVALUATION SUPPORT

The aim of t his evaluation kit is to enable you to become familiar with the functionality and

perform ance of the WM8816_EV1B Micro-Control l er Board.

If you require f urther informat i on or requi re t echnical support pl ease contact Wolf son

Microelect roni cs Applicat ions group through the foll owing channel s:

Email: apps@wolfson.co.uk

Telephone : (+44) 131 667 9386

Fax: (+44) 131 667 5176

Mail: Appli cations at the address on page 1.

Or contac t your local Wolfson representative.

Additional information may be made avail abl e f rom tim e to time on our web sit e at

http://www.wolfson.co.uk