Production Data
WM8776
Figure 19 DSP/PCM Mode Audio Interface (mode B, LRP=0, Slave)
CONTROL INTERFACE OPERATION
The WM8776 is controlled by writing to registers through a serial control interface. A control word
consists of 16 bits. The first 7 bits (B15 to B9) are address bits that select which control register is
accessed. The remaining 9 bits (B8 to B0) are data bits, corresponding to the 9 bits in each control
register. The control interface can operate as either a 3-wire or 2-wire MPU interface. The MODE pin
selects the interface format, as shown in Table 10. .
MODE
Control Mode
2 wire interface
3 wire interface
0
1
Table 10 Control Interface Selection via MODE Pin
3-WIRE (SPI COMPATIBLE) SERIAL CONTROL MODE
In 3-wire mode, every rising edge of CL clocks in one data bit from the DI pin. A rising edge on CE
latches in a complete control word consisting of the last 16 bits. The 3-wire interface protocol is
shown in Figure 20.
latch
CE
CL
DI
B15
B14
B13
B12
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
B1
B0
control register address
control register data bits
Figure 20 3-wire SPI Compatible Interface
1. B[15:9] are Control Address Bits
2. B[8:0] are Control Data Bits
3. CE is edge sensitive – the data is latched on the rising edge of CE.
PD Rev 4.0 April 2005
23
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
