WM9704M

Production Data

WOLFSON MICROELECTRONICS LTD

PD Rev 3.2 January 2001

30

REGISTER 2CH TO 32H – AUDIO SAMPLE RATE CONTROL REGISTERS

These registers are read/write registers that are written to, to select alternative sample rates for the

audio PCM converters. Default is the 48ks/s rate. Note that only Rev 2.1 recommended rates are

supported by the WM9704M, selection of any other unsupported rates will cause the rate to default to

the nearest supported rate, and the supported rate value to be latched and so read back.

Register 2Ch is the front DAC rate register, but is also used for centre channel data rate.

MODEM REGISTERS (INDEX 3CH TO 56H)

The contents of these registers control modem function.

REGISTER 3CH – EXTENDED MODEM ID

The extended modem ID is a read/write register that primarily identifies the enhanced codecs modem

AFE capabilities. The default value will depend on features and hardware configuration. Writing any

value to this register performs a warm modem AFE reset (register range 3C-56h), including GPIO

(register range 4C-54h). The warm reset causes all affected registers to revert to their default values.

Note: for AMC ’97 parts the audio and modem AFE should be logically independent (writes to

register 0h resets audio only).

•

LIN1 = 1 indicates 1st line is supported – set when WM9704M is in Modem mode 1 = 1

•

LIN2 = 1 indicates 2nd line is supported – supported on WM9704M when DLM is set

•

HSET = 1 indicates handset DAC/ADC is supported – not supported on WM9704M

•

CID1 = 1 indicates that caller ID decode for line 1 is supported – not supported on WM9704M

•

CID2 = 1 indicates that caller ID decode for line 2 is supported – not supported on WM9704M

•

ID1, ID0 is a 2-bit field which indicates the Codec configuration: Primary is 00; Secondary is

01, 10, or 11

REGISTER 3EH – EXTENDED MODEM STATUS/CONTROL

The Extended Modem Status and Control register functions similarly to the original AC’97 Power-

down Control/Status register, located at index 26h. The (A)MC ’97 Codec must restrict modem and

handset power-down control/status to this register since all of the functions are provided here.

Therefore, the (A)MC’97 Codec (and AC’97 Digital Controller, of course) must ignore bits MDM and

PR7 in register 26h and use what is included here. When the GPIO section is powered down, all

outputs must be tri-stated and input slot 12 should be marked invalid when the AC-link is active.

When slot 12 is invalid, register 54h (GPIO Pin Status Register) will report 0s. In addition the Codec

should force SDATA_IN slot 12 to all 0s. Bits 7 to 0 are read only, 1 indicates modem AFE

subsystem readiness:

•

GPIO = 1 indicates GPIO ready

•

MREF = 1 indicates Modem VREFs up to nominal level

•

ADC1 = 1 indicates Modem Line1 ADC ready

•

DAC1 = 1 indicates Modem Line1 DAC ready

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ADC2 = 1 indicates Modem Line2 ADC ready – supported on WM9704M when in DLM is set

•

DAC2 = 1 indicates Modem Line2 DAC ready –supported on WM9704M when DLM is set

•

HADC = 1 indicates Handset ADC ready – not supported on WM9704M

•

HDAC = 1 indicates Handset DAC ready – not supported on WM9704M

Bits 15 to 8 are read/write and control modem AFE subsystem power-down. WM9704M

powerup/down functions are entirely controlled from register 26h. However, the following registers

are aliased onto the appropriate control bits in registers 26h.

•

PRA = 1 indicates GPIO power-down

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PRB = 1 indicates Modem VREF off - no separate modem VREF on WM9704M, aliases

from PR3

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PRC = 1 indicates Modem Line 1 ADC off – aliases from PR0

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PRD = 1 indicates Modem Line 1 DAC off - aliases from PR1

•

PRE = 1 indicates Modem Line 2 ADC off – not supported on WM9704M

•

PRF = 1 indicates Modem Line 2 DAC off – not supported on WM9704M

•

PRG = 1 indicates Handset ADC off – not supported on WM9704M

•

PRH = 1 indicates Handset DAC off – not supported on WM9704M