CS2100-CP Datasheet, PDF (23/32 Pages) Cirrus Logic – Fractional-N Clock Multiplier

CS2100-CP
eighth bit of the address is the R/W bit. If the operation is a write, the next byte is the Memory Address Point-
er (MAP) which selects the register to be read or written. If the operation is a read, the contents of the reg-
ister pointed to by the MAP will be output. Setting the auto increment 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 CS2100 after each input byte is read and is input 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 1 1 AD0 0
INCR 6 5 4 3 2 1 0
76
ACK
ACK
START
10
76
ACK
10
DATA +n
76 10
ACK
STOP
Figure 17. Control Port Timing, I²C Write
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 1 1 AD0 0
INCR 6 5 4 3 2 1 0
1 0 0 1 0 1 AD0 1
70
7
0
7
0
START
ACK
ACK
ACK
ACK
START
Figure 18. Control Port Timing, I²C Aborted Write + Read
NO
ACK _STOP
Since the read operation cannot set the MAP, an aborted write operation is used as a preamble. As shown
in Figure 17, 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 100111x0 (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 100111x1(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.
DS840PP1
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