WM9705 datasheet(23/55 Pages) WOLFSON

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WM9705

Production Data

PD Rev 4.0 December 2003

DATA SLOT MAPPING

DAC data and SPDIF data sent to the device, ADC data sent from the device, can be optionally

mapped into alternative slots under control of slot mapping bits located as follows:

SLOT MAPPING DATA

TYPE

CONTROL

BITS

DAC data

DSA[1,0]

28h

SPDIF data

SPSA[1,0]

2Ah

ADC data

ASS[1,0]

5Ch (non-AC’97 feature)

Table 4 Data Slot Mapping Control

Default values and functional behavior are further described in the Serial Interface Register Map

description. DAC slot mapping defaults are in Table 2.

AC-LINK DIGITAL SERIAL INTERFACE PROTOCOL

A digital interface has been provided to control the WM9705 and transfer data to and from it. This

serial interface is compatible with the Intel AC’97 specification.

The main control interface functions are:

•

Control of analogue gain and signal paths through the mixer

•

Bi-directional transfer of ADC and DAC words to and from AC’97 controller

•

Selection of power-down modes

•

Control of pen digitizer function

•

Transfer of pen digitizer information and auxiliary conversion results from the codec

The WM9705 incorporates a 5-pin digital serial interface that links it to the AC’97 controller. AC-

link is a bi-directional, fixed rate, serial PCM digital stream. It handles multiple input and output

audio streams, as well as control register accesses employing a time division multiplexed (TDM)

scheme. The AC-link architecture divides each audio frame into 12 outgoing and 12 incoming

data streams, each with 20-bit sample resolution. With a minimum required DAC and ADC

resolution of 16-bits, AC’97 may also be implemented with 18 or 20-bit DAC/ADC resolution,

given the headroom that the AC-link architecture provides. The WM9705 provides support for 18-

bit audio operation.

SLOT

NUMBER

SYNC

SDATAOUT

SDATAIN

TAG PHASE

TAG

CMD

ADR

CMD

DATA

PCM

LEFT

PCM

RIGHT

RSRVD

TAG

STATUS

ADDR

STATUS

DATA

PCM

LEFT

PCM

RIGHT

RSRVD

DATA PHASE

PCM C

(n+1)

PCM R

(n+1)

PCM L

(n+1)

CODEC ID

SLOTREQ 3-12

RSRVD

Figure 11 AC’97 Standard Bi-directional Audio Frame

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