WM8753L
Advanced Information
Figur
e 25 2-Wire Serial Control Interface
The WM8753L has two possible device addresses, which can be selected using the GPIO5/CSB pin.
The pin is sampled at power-up and selects the device address. After power-up the pin is available
for general purpose use in 2-wire interface mode.
GPIO5/CSB STATE
DEVICE ADDRESS
0011010
Low
High
0011011
Table 59 2-Wire MPU Interface
READ/WRITE OPERATION
The control interface of the WM8753L is a write only interface. However setting register bit READEN
in 3-wire mode will allow a status word to be read from the device. A status word consists of 8 bits.
Different status words are supported by the device, and are selected by changing the READSEL
register bits. The supported words are listed in Table 60.
In 3-wire mode an additional pin is required for serial data output from the device. This data can be
routed to the ADCDAT, GP1, GP2, GPIO3 or GPIO4 pins. The pin will be tri-state when the CSB pin
is high, allowing data from multiple sources to be connected to the same controller.
In 3-wire mode, reads and write occur simultaneously (i.e. data is clocked in and out at the same
time). Usually a read can be paired with a write, but if this is not possible it is recommended that
reads be paired with a dummy write to register R0, which is unused.
REGISTER
ADDRESS
BIT
LABEL
RDDAT
DEFAULT
DESCRIPTION
R24 (18h)
Read Control
4
0
Selects ADCDAT as SDOUT for 3-wire
readback
0 = ADCDAT not selected for readback
1 = ADCDAT selected for readback
3:1
0
READSEL
READEN
000
0
Read register select
See table Table 61 below
Control interface read enable
0 = Control interface is write only
1 = Control interface supports read and
write.
Table 60 Control Interface Control
AI Rev 3.1 June 2004
63
w
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
