WM9705 datasheet(30/55 Pages) WOLFSON

30 / 55 page

WM9705

Production Data

PD Rev 4.4 August 2006

Within normal audio frames SYNC is synchronous to the WM9705 input. However, in the absence

of BITCLK, SYNC is treated as an asynchronous input used in the generation of a warm reset to

the WM9705. The WM9705 will not respond with the activation of BITCLK until SYNC has been

sampled low again by the WM9705. This will preclude the false detection of a new audio frame.

PEN DOWN WM9705 WAKE-UP

If pen down is detected when the device is in low power halted mode with PRP[1:0] set to 01 and

RPR set to 1, PR4 will be reset and the CODEC will transition SDATAIN from low to high to

indicate a wakeup to the controller for it to restart the ACLINK. This wakeup mode is disabled

when RPR is set.

POWER DOWN DURING WM9705 RESET – HARDWARE POWER DOWN MODE

Note that the normal default condition of WM9705 when RESETB is applied is ‘all active’.

However, if pin 43 MASK is pulled ‘hi’ during RESETB active, all PR bits are overridden and the

device enters a low power mode. This allows a low power standby mode to be entered without

writing to the device, a condition that is desirable for example, if batteries are changed in a PDA.

The state of MASK is latched on the rising edge of RESETB and if MASK is ‘hi’ the device will

remain in low power mode until register 26h is written to.

SERIAL INTERFACE REGISTER MAP DESCRIPTION

(See Table 23)

The serial interface bits perform control functions described as follows: The register map is fully

specified by the AC’97 specification, and this description is simply repeated below, with optional

unsupported features omitted.

RESET REGISTER (INDEX 00h)

Writing any value to this register performs a register reset, which causes all registers to revert to

their default values. Reading this register returns the ID code of the part, indication of modem

support (not supported by the WM9705) and a code for the type of 3D stereo enhancement.

The ID decodes the capabilities of the WM9705 based on the following:

BIT

FUNCTION

VALUE ON

WM9705

ID0

Dedicated Mic PCM in channel

ID1

Modem line codec support

ID2

Bass and treble control

ID3

Simulated stereo (mono to stereo)

ID4

Headphone out support

ID5

Loudness (bass boost) support

ID6

18-bit DAC resolution

ID7

20-bit DAC resolution

ID8

18-bit ADC resolution

ID9

20-bit ADC resolution

SE4...SE0

Wolfson Microelectronics 3D enhancement

11000

Table 7 Reset Register Function

Note that the WM9705 defaults to indicate 18-bit compatibility.

PLAY MASTER VOLUME REGISTERS (INDEX 02h, 04h AND 06h)

These registers manage the output signal volumes. Register 02h controls the stereo master

volume (both right and left channels), Register 04h controls the stereo headphone out, and

∞dB.

ML4 to ML0 is for left channel level, MR4 to MR0 is for the right channel and MM4 to MM0 is for

the mono out channel.

WM9705 Datasheet(PDF) 30 Page - Wolfson Microelectronics plc

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