wm9704q Wolfson Microelectronics plc, wm9704q Datasheet - Page 31

• Manufacturer Part Number: wm9704q
• Description: 4-channel Surround Sound Codec
• Manufacturer: Wolfson Microelectronics plc

Production Data
VENDOR RESERVED REGISTERS (INDEX 5Ah AND 7Ah)
WOLFSON MICROELECTRONICS LTD
REGISTER 54h – GPIO PIN STATUS
The GPIO status is a read/write register that reflects the state of all GPIO pins (inputs and outputs)
on slot 12. The value of all GPIO pin inputs and outputs comes in from the codec every frame on slot
12, but is also available for reading as GPIO Pin Status via the standard slot 1 and 2 command
address/data protocols. GPIO inputs configured as Sticky are cleared by writing a 0 to the
corresponding bit of this register 54h.
Bits corresponding to unimplemented GPIO pins should be forced to zero in this register and input
slot 12. GPIO bits that have been programmed as Inputs and Sticky, upon transition either (high-to
low) or (low-to-high) depending on pin polarity, will cause the individual GPIO bit to go asserted 1,
and remain asserted until a write of 0 to that bit. The normal way to set the desired value of a GPIO
output pin is to set the control bit in output slot 12.
The default value, if configured as an input, after cold or register reset for this register is always the
state of the GPIO pin.
REGISTER 56h – MISCELLANEOUS MODEM AFE STATUS/CONTROL
Not supported in this mode.
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. Values stored
in this register are used to provide vendor specific modes for the manufacturer.
Table 22 Vendor Register 5Ah Bit Allocation and Default States
VENDOR SPECIFIC GAIN CONTROL REGISTERS – (INDEX 70h TO 74h)
These three registers control the gain and mute functions applied to the front and rear mixer paths,
and the rear channel DAC gains. These PGAs are not accommodated in the Intel specification, but
are required in order to build a flexible quad surround sound device. The function is as per the other
mixer PGAs. However, the default value of the register changes depending upon the MODE the
device is operating in, as shown in Table 23.
Table 23 Vendor Specific PGA Default Values
VENDOR ID REGISTERS (INDEX 7Ch TO 7Eh)
This register is for specific vendor identification if so desired. The ID method is Microsoft’s Plug and
Play Vendor ID code. The first character of that ID is F7 to F0, the second character S7 to S0, and
the third T7 to T0. These three characters are ASCII encoded. The REV7 to REV0 field is for the
Vendor Revision number. In WM9704Q the vendor ID is set to WML3 if MODE1 = 0, and WML4 if
MODE1 = 1.
Wolfson is a registered Microsoft Plug and Play vendor.
User bits
Rev 2.1 (00)
Rev 2.1 6-channel
(01)
Quad (10)
BIT
AMD
AND
DLM
R2S
I
2
S
MODE
NAME
ADC no DAC
Rev 2.1 switch
I
Dual line modem
Automute disable
2
S enable
REAR DAC –
REG 70H
8808
8808
8808
DEFAULT
0
0
0
0
0
DEFAULT VALUE FOR REGISTER
FRONT MIXER –
REG 72H
ACTION WHEN SET TO 1
Select stereo mix into ADC as having no DAC
signal
Closes Rev 2.1 switch when set (see fig 1)
Enables I
43,44,48
Selects support for Line2 DAC and ADC slots
Disables automute function on the front and
rear DACs
0808
0808
0808
2
S data and clock onto GPIO pins
REAR MIXER –
REG 74H
8808
8808
0808
PD Rev 2.3 January 2001
WM9704Q
SWITCH
REV 2.1
Closed
Closed
Open
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