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SCP_CLK
SCP_SDA
Write
Read
SCP_CLK
SCP_SDA
Write
Read
After an ACK or NACK from the master or slave, the slave must leave the SCP_SDA line high so the master
can then generate either a Stop condition to abort the transfer, or a another Start condition to start a new
transfer.
SCP_CLK
SCP_SDA
Write
Read
SCP_CLK
SCP_SDA
Write
Read
If a slave can't receive or transmit another complete byte of data until it has performed some other function,
for example servicing an internal interrupt, it can hold the SCP_CLK line low to force the master into a wait
state. Data transfer then continues when the slave is ready for another byte of data and releases SCP_CLK.
DS734UM7
Start
A[6]
A[5]
A[4]
A[3]
A[2]
A[1]
M
M
Start
A[6]
A[5]
A[4]
A[3]
A[2]
A[1]
M
M
Figure 3-5. Data Byte with ACK and NACK
M = Master Drives SDA
S = Slave Drives SDA
Figure 3-6. Stop Condition with ACK and NACK
Copyright 2009 Cirrus Logic, Inc.
A[0]
R/W ACK
S
S
A[0]
R/W ACK
S
S
M = Master Drives SDA
S = Slave Drives SDA
Data Byte
M
S
Data Byte
M
S
Serial Control Port Configuration
CS485xx Hardware User's Manual
Data Byte
ACK
M
S
S
M
Data Byte
NACK
M
S
S
M
Stop
ACK
S
M
M
M
Stop
NACK
S
M
M
M
3-6
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