xwm8722eds ETC-unknow, xwm8722eds Datasheet - Page 13

• Manufacturer Part Number: xwm8722eds
• Description: Stereo Dac With Integrated Tone Generator And Line/variable Level Outputs
• Manufacturer: ETC-unknow

WM8722
SERIAL CONTROL OPERATION
To control the WM8722 on the bus, the master must initiate a data transfer by establishing a start
condition, defined by a high-to-low transition on MD whilst MC remains high. This indicates that an
address and data transfer will follow. All peripherals respond to the start condition and shift the next
eight bits (7-bit address + R/W bit). The transfer is MSB first. The peripheral that recognises the
transmitted address responds by pulling the data line low during the ninth clock pulse (acknowledge
bit). All other devices withdraw from the bus and maintain an idle condition once the appropriate
peripheral has been recognised. The idle condition is where the device monitors the MD and MC
lines waiting for a start condition and the correct transmitted address. The R/W bit determines the
direction of data transfer. The WM8722 is a write only device and only responds to the R/W bit
indicating a write.
The WM8722 acts as a standard slave device on the bus. The data on the MD is clocked in by MC.
The first 6 bits (which must be 100000) are clocked into the WM8722 followed by a programmable
address bit to select one of the two available addresses. The eighth bit of the address byte is the
R/W bit. The WM8722 checks this bit and responds if it is a write. If the correct address is sent by
the master, the WM8722 acknowledges the bus master (ACK) and pulls the bus low. The next byte is
the register address. Each subsequent byte of data is separated by an acknowledge bit.
A stop condition is defined when there is a low-to-high transition on MD when MC is high.
If a stop or start condition is detected out of sequence at any point in the data transfer, the device
jumps to the idle condition.
Control of the various modes of operation is software controled over the 2 or 3-wire serial interface.
The following functions may be controlled via the serial control interface:
Input audio data format
Input Word Length
De-emphasis selection
Power off control
Analogue output mode
Mute
Input LRCIN polarity
Master Volume Control
FUNCTION
LATCH STATE
1
0
Normal format
I
16
20
24
On
Off
Enable
disable
L, R, mono, Mute
On (Muted)
Off (Un-muted)
Lch/Rch = Hi/Lo
Lch/Rch = Lo/Hi
Lch, Rch individually
Lch, Rch both
2
S format
1000001 (0x82)
1000000 (0x80)
Address
OPTIONS
Normal format (0)
16 bit (0)
Off (0)
Enabled (0)
Stereo (1001)
Off (0)
Lch/Rch = Hi/Lo (0)
0dB (1111001)
Lch, Rch individually (0)
SOFTWARE CONTROL
DEFAULT VALUE
AI Rev 2.1 June 2001
Advanced Information
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