Cirrus Logic CS4385A - Manual (Page 33)

DS837F2 33
CS4385A
2. After transmitting an acknowledge (ACK), the device will then transmit the contents of the register
pointed to by the MAP. The MAP register will contain the address of the last register written to the
MAP, or the default address (see
Section 5.1 ) if an I²C read is the first operation performed on the
device.
3. Once the device has transmitted the contents of the register pointed to by the MAP, issue an ACK.
4. If the INCR bit is set to 1, the device will continue to transmit the contents of successive registers.
Continue providing a clock and issue an ACK after each byte until all the desired registers are read;
then initiate a STOP condition to the bus.
5. If the INCR bit is set to 0 and further I²C reads from other registers are desired, it is necessary to initiate
a repeated START condition and follow the procedure detailed in steps 1 and 2 of the I²C Write
instructions, followed by step 1 of the I²C Read section. If no further reads from other registers are
desired, initiate a STOP condition to the bus.
5.3 SPI Mode
In SPI Mode, data is clocked into the serial control data line, CDIN, by the serial control port clock, CCLK
(see
Figure 26 for the clock-to-data relationship). There is no AD0 pin. The CS pin is the chip select signal
and is used to control SPI writes to the control port. When the device detects a high-to-low transition on the
AD0/CS pin after power-up, SPI Mode will be selected. All signals are inputs and data is clocked in on the
rising edge of CCLK.
5.3.1 SPI Write
To write to the device, follow the procedure below while adhering to the control port Switching Specifica-
tions in
Switching Characteristics - Control Port - SPI Format .
1. Bring CS low.
2. The address byte on the CDIN pin must then be 00110000.
3. Write to the memory address pointer, MAP. This byte points to the register to be written.
4. Write the desired data to the register pointed to by the MAP.
5. If the INCR bit (see
Section 5.1 ) is set to 1, repeat the previous step until all the desired registers are
written; then bring CS high.
6. If the INCR bit is set to 0 and further SPI writes to other registers are desired, it is necessary to bring
CS high and follow the procedure detailed in step 1. If no further writes to other registers are desired,
bring CS high.
SDA
SC L
001100
ADDR
AD0
R/W
Start
ACK
DATA
1-8
ACK
DATA
1-8
ACK
Stop
N ote: If operation is a write, this byte contains the M em ory A ddress Pointer, M A P.
Note 1
Figure 25. Control Port Timing, I²C Mode