WM8731 / WM8731L
Production Data
3-WIRE (SPI COMPATIBLE) SERIAL CONTROL MODE
The WM8731/L can be controlled using a 3-wire serial interface. SDIN is used for the program data,
SCLK is used to clock in the program data and CSB is use to latch in the program data. The 3-wire
interface protocol is shown in Figure 33.
CSB
SCLK
B15
B14
B13
B12
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
B1
B0
SDIN
Figure 33 3-Wire Serial Interface
Notes:
1. B[15:9] are Control Address Bits
2. B[8:0] are Control Data Bits
3. CSB is edge sensitive not level sensitive. The data is latched on the rising edge of CSB.
2-WIRE SERIAL CONTROL MODE
The WM8731/L supports a 2-wire MPU serial interface. The device operates as a slave device only.
The WM8731/L has one of two slave addresses that are selected by setting the state of pin 15,
(CSB).
ACK
ACK
ACK
DATA B15-8
R ADDR
R/W
DATA B7-0
SDIN
SCLK
START
STOP
Figure 34 2-Wire Serial Interface
Notes:
1. B[15:9] are Control Address Bits
2. B[8:0] are Control Data Bits
CSB STATE
ADDRESS
0
1
0011010
0011011
Table 25 2-Wire MPU Interface Address Selection
To control the WM8731/L on the 2-wire bus the master control device must initiate a data transfer by
establishing a start condition, defined by a high to low transition on SDIN while SCLK remains high.
This indicates that an address and data transfer will follow. All peripherals on the 2-wire bus respond
to the start condition and shift in the next eight bits (7-bit address + R/W bit). The transfer is MSB
first. The 7-bit address consists of a 6-bit base address + a single programmable bit to select one of
two available addresses for this device (see Table 24). If the correct address is received and the
R/W bit is ‘0’, indicating a write, then the WM8731/L will respond by pulling SDIN low on the next
clock pulse (ACK). The WM8731/L is a write only device and will only respond to the R/W bit
indicating a write. If the address is not recognised the device will return to the idle condition and wait
for a new start condition and valid address.
PD, Rev 4.8, April 2009
46
w
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
