Advance Information
Acknowledge Polling
CAT1320, CAT1321
Read Operations
Disabling of the inputs can be used to take advantage of
the typical write cycle time. Once the stop condition is
issuedtoindicatetheendofthehost’swriteopration, the
CAT1320/21initiatestheinternalwritecycle.ACKpolling
can be initiated immediately. This involves issuing the
start condition followed by the slave address for a write
operation.Ifthedeviceisstillbusywiththewriteoperation,
no ACK will be returned. If a write operation has
completed, an ACK will be returned and the host can
then proceed with the next read or write operation.
The READ operation for the CAT1320/21 is initiated in
the same manner as the write operation with one
exception, that R/W bit is set to one. Three different
READ operations are possible: Immediate/Current
Address READ, Selective/Random READ and
Sequential READ.
Figure 10. Immediate Address Read Timing
S
T
A
R
T
S
T
O
P
BUS ACTIVITY:
MASTER
SLAVE
ADDRESS
SDA LINE
S
P
A
C
K
N
O
DATA
A
C
K
SCL
SDA
8
9
8TH BIT
DATA OUT
NO ACK
STOP
Doc No. 25085, Rev. 00
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