CS4341

DS298F5

23

4.9.4

SPI Mode

In SPI mode, data is clocked into the serial control data line, CDIN, by the serial control port clock,

CCLK (see Figure 24 for the clock to data relationship). There is no AD0 pin. Pin CS 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.

4.9.4a

SPI Write

To write to the device, follow the procedure below while adhering to the control port Switching

Specifications in section 1.

1)

Bring CS low.

2)

The address byte on the CDIN pin must then be 00100000.

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 4.9.2a) 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 repeat the procedure detailed from step 1. If no further writes to other

registers are desired, bring CS high.

SD A

SC L

001000

AD0

W

Sta rt

ACK

MAP

1-8

ACK

001000

AD0

R

Repeated START

or

Aborted W RITE

ACK

Data 1-8

(pointed to by MAP)

Data 1-8

(pointed to by MAP)

ACK

Stop

Figure 23. I²C Read

MAP

MSB

LSB

DATA

byte 1

byte n

R/W

MAP = Memory Address Pointer

ADDRESS

CHIP

CDIN

CCLK

CS

0010000

Figure 24. Control Port Timing, SPI Mode