CS42888_07 Datasheet, PDF (35/61 Pages) Cirrus Logic – 108 dB, 192 kHz 4-In, 8-Out CODEC

CS42888
next byte is the Memory Address Pointer (MAP) which selects the register to be read or written. If the op-
eration is a read, the contents of the register pointed to by the MAP will be output. Setting the auto-incre-
ment bit in MAP allows successive reads or writes of consecutive registers. Each byte is separated by an
acknowledge bit. The ACK bit is output from the CS42888 after each input byte is read, and is input to the
CS42888 from the microcontroller after each transmitted byte.
SCL
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 24 25 26 27 28
CHIP ADDRESS (WRITE)
MAP BYTE
DATA
DATA +1
SDA
1 0 0 1 0 AD1 AD0 0
INCR 6 5 4 3 2 1 0
76
ACK
ACK
START
10
76
ACK
10
Figure 23. Control Port Timing, I²C Write
DATA +n
76 10
ACK
STOP
SCL
SDA
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
CHIP ADDRESS (WRITE)
MAP BYTE
STOP
CHIP ADDRESS (READ)
DATA
DATA +1 DATA + n
1 0 0 1 0 AD1 AD0 0
INCR 6 5 4 3 2 1 0
1 0 0 1 0 AD1 AD0 1
70
7
0
7
0
START
ACK
ACK
START
ACK
ACK
NO
ACK _STOP
Figure 24. Control Port Timing, I²C Read
Since the read operation cannot set the MAP, an aborted write operation is used as a preamble. As shown
in Figure 24, the write operation is aborted after the acknowledge for the MAP byte by sending a stop con-
dition. The following pseudocode illustrates an aborted write operation followed by a read operation.
Send start condition.
Send 10010xx0 (chip address & write operation).
Receive acknowledge bit.
Send MAP byte, auto increment off.
Receive acknowledge bit.
Send stop condition, aborting write.
Send start condition.
Send 10010xx1(chip address & read operation).
Receive acknowledge bit.
Receive byte, contents of selected register.
Send acknowledge bit.
Send stop condition.
Setting the auto-increment bit in the MAP allows successive reads or writes of consecutive registers. Each
byte is separated by an acknowledge bit.
DS717F2
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