wm9701acftv Wolfson Microelectronics plc, wm9701acftv Datasheet - Page 16

• Manufacturer Part Number: wm9701acftv
• Description: Power Ac97 Multimedia Audio Codec
• Manufacturer: Wolfson Microelectronics plc

WM9701A
WOLFSON MICROELECTRONICS LTD.
The ID decodes the capabilities of WM9701A based on the following:
Table 1 Reset Register Function
Note that WM9701A defaults to indicate 18-bit compatibility. However, a control bit may be set in the
vendor - specific registers that changes bits ID6 and ID8 to be ‘0’, indicating a 16-bit device. It is
unlikely that this function will be required, however, as the MSB justification of the ADC and DAC
data means that a nominally 18-bit device should be fully compatible with controllers that only
provide 16-bit support. (Most PC type applications will only require 16-bit operation).
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 optional stereo headphone out, and
Register 06h controls the mono volume output. Each step corresponds to 1.5dB. The MSB of the
register is the mute bit. When this bit is set to 1 the level for that channel is set at -
ML5 to ML0 is for left channel level, MR5 through MR0 is for the right channel and MM5 to MM0 is
for the mono out channel.
Support for the MSB of the level is not provided by WM9701A. If the MSB is written to then
WM9701A detects when that bit is set and sets all 4 LSBs to 1s. Example: If the driver writes a
1xxxxx WM9701A interprets that as x11111. It will also respond when read with x11111 rather than
1xxxxx, the value written to it. The driver can use this feature to detect if support for the 6th bit is
there or not.
The default value of both the mono and the stereo registers is 8000h (1000 0000 0000 0000), which
corresponds to 0dB gain with mute on.
Table 2 Volume Register Function
MASTER TONE CONTROL REGISTERS (INDEX 08h)
Optional register for support of tone controls (bass and treble). WM9701A does not support bass
and treble and writing to this register will have no effect, reading will result in all don’t care values.
PC BEEP REGISTER (INDEX 0Ah)
This controls the level for the PC-beep input. Each step corresponds to approximately 3dB of
attenuation. The MSB of the register is the mute bit. When this bit is set to 1 the level for that
channel is set at -
WM9701A defaults to the PC-beep path being muted, so an external speaker should be provided
within the PC to alert the user to power on self-test problems.
ID0
ID1
ID2
ID3
ID4
ID5
ID6
ID7
ID8
ID9
SE4....SE
0
0
0
0
1
BIT
MUTE
Dedicated Mic PCM in channel
Modem line Codec support
Bass and treble control
Simulated stereo (mono to stereo)
Headphone out support
Loudness (bass boost) support
18-bit DAC resolution
20-bit DAC resolution
18-bit ADC resolution
20-bit ADC resolution
No stereo enhancement
dB.
0 0000
0 0001
1 1111
x xxxx
FUNCTION
MX4...MX0
0dB attenuation
1.5dB attenuation
46.5dB attenuation
dB attenuation
VALUE ON WM9701A
FUNCTION
PD Rev 3.2 January 2001
00000
0
0
0
0
0
0
1
0
1
0
Production Data
dB.
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