WM9704CFT/V Wolfson Microelectronics plc, WM9704CFT/V Datasheet - Page 16

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

WM9704M
SLAVE CODEC REGISTER ACCESS DEFINITIONS
CONTROL INTERFACE
WOLFSON MICROELECTRONICS LTD
Table 7 Slot to DAC Mapping Based on Mode and Codec ID
Master Codec access is exactly as defined for AC’97. For slave Codec access, the AC’97 Digital
Controller must invalidate the tag bits for Slot 1 and 2 Command Address and Data (Slot 0, bits 14
and 13) and place a non-zero value (01, 10, or 11) into the Codec ID field (Slot 0, bits 1 and 0).
Slave Codecs disregard the Command Address and Command Data (Slot 0, bits 14 and 13) tag bits
when they see a 2-bit Codec ID value (Slot 0, bits 1 and 0) that matches their configuration. In a
sense the Slave Codec ID field functions as an alternative Valid Command Address (for Slave reads
and writes) and Command Data (for Slave writes) tag indicator.
Slave Codecs must monitor the Frame Valid bit, and ignore the frame (regardless of the state of the
Slave Codec ID bits) if it is not valid. AC’97 Digital Controllers should set the frame valid bit for a
frame with a slave register access, even if no other bits in the output tag slot except the Slave Codec
ID bits are set.
Table 8 Slave Codec Register Access Slot 0-Bit Definitions
A digital interface has been provided to control the WM9704M and transfer data to and from it. This
serial interface is compatible with the Intel AC’97 specification as illustrated in the System Diagram
(Figure 7).
The main control interface functions are:
Modem (11)
OUTPUT TAG SLOT (16-BITS)
New definitions for Slave Codec Register Access
Rev 2.1
MODE
(00)
12-3
Control of analogue gain and signal paths through the mixer
Bi-directional transfer of ADC and DAC words to and from AC’97 controller
Selection of powerdown modes
BIT
1-0
15
14
13
2
DESCRIPTION
Frame Valid
Slot 1 Valid Command Address Bit (Master Codec only)
Slot 2 Valid Command Data Bit (Master Codec only)
Slot 3-12 Valid Bits as defined by AC’97
Reserved (Set to 0)
2-bit Codec ID field (00 reserved for Master; 01, 10, 11 indicate Slave)
00 or 01
00 or 01
10
11
10
11
ID
SLOTS MAPPED TO
FRONT DACS
3 and 4
7 and 8
6 and 9
3 and 4
7 and 8
6 and 9
SLOTS MAPPED TO REAR
(or 5 & 10 if DLM set)
Not supported
in this mode
PD Rev 3.2 January 2001
DACS
5
Production Data
16