wm9705seft-v Wolfson Microelectronics plc, wm9705seft-v Datasheet - Page 31

• Manufacturer Part Number: wm9705seft-v
• Description: Multimedia Ac?97 Codec With Integrated Touch Screen Controller
• Manufacturer: Wolfson Microelectronics plc

WM9705
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Support for the MSB of the volume level is not provided by the WM9705. If the MSB is written to,
then the WM9705 detects when that bit is set and sets all 4 LSBs to 1s. Example: If the driver
writes a 1xxxxx the WM9705 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 8 Volume Register Function
The Headphone out has an additional 6dB boost, selectable by setting HPB in register 74h.
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 -
WM9705 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.
Table 9 PC-beep Register Function
ANALOGUE MIXER INPUT GAIN REGISTERS (INDEX 0Ch - 18h AND 72h)
This controls the gain/attenuation for each of the analogue inputs and mixer PGA. Each step
corresponds to approximately 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 -
channels is fixed at 0dB. Writes to the gain control bits for these channels are ignored, and the
value of readback for these registers is always the default, with the exception of the mute bit 15
which may be written to and read from.
The default value for the mono registers is 8008h, which corresponds to 0dB gain with mute on.
The default value for stereo registers is 8808h, which corresponds to 0dB gain with mute on.
Table 10 Mixer Gain Control Register Function
REGISTER 0Eh (MIC VOLUME REGISTER)
This has an extra bit that is for a 20dB boost. When bit 6 is set to 1 the 20dB boost is on. The
default value is 8008h, which corresponds to 0dB gain with mute on.
RECORD SELECT CONTROL REGISTER (INDEX 1Ah)
Used to select the record source independently for right and left (see Table 11). The default value
is 0000h, which corresponds to Mic in. Setting Bit ADCNDAC in Register 5Ch selects a stereo mix
WITHOUT DAC when (5 x 2 – 5 x 0) is 5.
MUTE
MUTE
MUTE
0
0
0
1
0
0
1
0
0
0
1
MX4...MX0
GX4...GX0
PV3...PV0
∞
0 0000
0 0001
1 1111
x xxxx
00000
01000
11111
xxxxx
0000
1111
xxxx
dB.
FUNCTION
0dB attenuation
1.5dB attenuation
46.5dB attenuation
∞
FUNCTION
0dB attenuation
45dB attenuation
∞
FUNCTION
+12dB gain
0dB gain
-34.5dB gain
-
∞
dB attenuation
dB attenuation
dB gain
∞
dB. Note that the gain for the VID and AUX input
PD Rev 4.5 July 2008
Production Data
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