WM8802
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DEMODULATION FUNCTION MASTER/SLAVE SETTINGS (CKST )
A master/slave function allows multi-channel synchronized transfer using multiple WM8802 devices.
A 10kΩ pull-down or a pull-up resistor should be connected to CKST to set this function.
Set the master mode when using only one WM8802. When using multiple WM8802 devices, set one
to the master mode and the others to slave mode.
In order to perform multi-channel transfer when using multiple WM8802 devices, RBCK and RLRCK
(output) should be connected as the master and RLRCK (input) as the slave. XMCK of the master
device should be connected to XIN of the slave device. The same polarity should be set for RBCK
and RLRCK and the same frequency for XIN and XMCK.
Some of the output data maybe dropped or read twice on the slave side if the input data sampling
frequency or the phase between the master and slave differ. This can also be true if the clock
sources differ even though the sampling frequencies are the same. This phenomenon can be
checked using the INT pin and the micro-controller interface.
MODE
CKST
Pull-down
Pull-up
Master mode
Slave mode
Table 3 Master/Slave Switching
PIN
RMCK
RBCK
RLRCK
MASTER MODE
Output
SLAVE MODE
Low
Input
Input
Output
Output
Table 4 Clock Pin State
MODULATION FUNCTION AND GENERAL-PURPOSE I/O PORT SWITCHING (INT )
The modulation function and the general-purpose I/O function share the same pin and therefore
cannot be used simultaneously.
A 10kΩ pull-down or pull-up resistor can be connected to INT to select the function listed in Table
5.
INT STATE
pull-down
Pull-up
FUNCTION
Modulation f unction
General-purpose I/O
Table 5 Modulation Function and General-Purpose I/O Switching
PP Rev 1.1 April 2004
12
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
