WM9707 Datasheet, PDF (25/30 Pages) Wolfson Microelectronics plc – AC97 Revision 2.1 Audio Codec with Spdif Output

Advanced Information
WM9707
DATA BIT FUNCTION
READ/WRITE
VRA
Enables variable rate audio mode
Read/write
DRA
Enable double rate audio mode
Read/write
VRM
Enables variable rate Mic ADC
Read/write
CDAC
Indicates centre DAC ready
Read
SDAC
Indicates surround DAC ready
Read
LDAC
Indicates LFE DAC ready
Read
MADC
Indicates Mic ADC ready
Read
PRI
Set to turn off centre DAC
Read/write
PRJ
Set to turn off surround DACs
Read/write
PRK
Set to turn off LFE DACs
Read/write
PRL
Set to turn off Mic ADC
Read/write
Table 14 Extended Audio Status and Control Register
WM9707 SUPPORT
Yes
No
No
No
No
No
No
No
No
No
No
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 Revision 2.1 recommended rates
are supported by the WM9707, 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.
Note that the SPDIF mode only supports 48ks/s rate.
REGISTERS 36h AND 38h – 6 CHANNEL VOLUME CONTROL
These read/write registers control the output volume of the optional four PCM channels. (not
supported by the WM9707)
VENDOR RESERVED REGISTERS (INDEX 5Ah - 7Ah)
These registers are vendor specific. Do not write to these registers unless the Vendor ID register has
been checked first to ensure that the driver knows the source of the AC ‘97 component.
SPDIF DIGITAL AUDIO DATA OUTPUT – (INDEX 5Ch)
The WM9707 provides an SPDIF output. In order to enable this output, bit SPDF in Register 5Ch
should be set. Additionally, a bit SCMS in Register 5Ch may also be set, which sets the copyright
flag in the IEC958 data, allowing serial copy protect mechanisms to be removed.
The WM9707 can be programmed to automute the DACs. By setting the mute bit, the WM9707 will
mute the DACs when it detects a continuous sequence of 1024 zeros.
WOLFSON MICROELECTRONICS LTD
AI Rev 2.2 January 2001
25