CS4351
4.9
Control Port Interface
The control port is used to load all the internal register settings (see
The operation of the control
port may be completely asynchronous with the audio sample rate. However, to avoid potential interference
problems, the control port pins should remain static if no operation is required.
The control port operates in one of two modes: I²C or SPI.
4.9.1
MAP Auto Increment
The device has MAP (memory address pointer) auto increment capability enabled by the INCR bit (also
the MSB) of the MAP. If INCR is set to 0, MAP will stay constant for successive I²C writes or reads and
SPI writes. If INCR is set to 1, MAP will auto increment after each byte is written, allowing block reads or
writes of successive registers.
4.9.2
I²C Mode
In the I²C mode, data is clocked into and out of the bi-directional serial control data line, SDA, by the serial
control port clock, SCL (see
for the clock to data relationship). There is no CS pin. Pin AD0 en-
ables the user to alter the chip address (100110[AD0][R/W]) and should be tied to VL or GND as required,
before powering up the device. If the device ever detects a high to low transition on the AD0/CS pin after
power-up, SPI mode will be selected.
4.9.2.1
I²C Write
To write to the device, follow the procedure below while adhering to the control port Switching Specifica-
tions in
1. Initiate a START condition to the I²C bus followed by the address byte. The upper 6 bits must be
100110. The seventh bit must match the setting of the AD0 pin, and the eighth must be 0. The eighth
bit of the address byte is the R/W bit.
2. Wait for an acknowledge (ACK) from the part, then write to the memory address pointer, MAP. This
byte points to the register to be written.
3. Wait for an acknowledge (ACK) from the part, then write the desired data to the register pointed to
by the MAP.
4. If the INCR bit (see
is set to 1, repeat the previous step until all the desired registers
are written, then initiate a STOP condition to the bus.
5. If the INCR bit is set to 0 and further I²C writes to other registers are desired, it is necessary to initiate
a repeated START condition and follow the procedure detailed from step 1. If no further writes to oth-
er registers are desired, initiate a STOP condition to the bus.
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DS566F1
CIRRUS [ CIRRUS LOGIC ]
