Cirrus Logic CS4398 - Manual (Page 27)

DS568F1 27
CS4398
Figure 15. Control Port Timing, SPI Format (Write)
5.5.2 Reading in SPI
Figure 16 shows the operation of the Control Port in SPI format. To read to a register, bring CS low. The
first seven bits on CDIN form the chip address and must be 1001100. The eighth bit is a read/write control
(R/W), which must be high to read. The CDOUT line will then output the data from the register designated
by the MAP. To read multiple registers, keep CS low and continue providing clocks on CCLK. End the
read transaction by setting CS high. The CDOUT line will go to a high-impedance state once CS goes
high.
Figure 16. Control Port Timing, SPI Format (Read)
MAP
MSB LSB
DATA
byte 1 byte n
R/W
MAP = Memory Address Pointer
ADDRESS
CHIP
CDIN
CCLK
CS
1 0 0 1 1 0 0
L S B
b y te 1 b y te n
R /W
A D D R E S S
C H IP
C D IN
C C L K
C S
1 0 0 1 1 0 0
M S B
DATA
C D O U T