WM9704CFT/V Wolfson Microelectronics plc, WM9704CFT/V Datasheet - Page 30

• Manufacturer Part Number: WM9704CFT/V
• Description: AMC97 Audio and Modem Codec
• Manufacturer: Wolfson Microelectronics plc

WM9704M
MODEM REGISTERS (INDEX 3CH TO 56H)
WOLFSON MICROELECTRONICS LTD
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.
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).
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:
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.
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
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
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
PRA = 1 indicates GPIO power-down
PRB = 1 indicates Modem VREF off - no separate modem VREF on WM9704M, aliases
from PR3
PRC = 1 indicates Modem Line 1 ADC off – aliases from PR0
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
PD Rev 3.2 January 2001
Production Data
30