PCA9557 查看數據表（PDF） - Philips Electronics
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PCA9557 Datasheet PDF : 16 Pages
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Philips Semiconductors
8-bit I2C and SMBus I/0 port with reset
Product data
PCA9557
Bus Transactions
Data is transmitted to the PCA9557 registers using Write Byte transfers (see Figures 12 and 13). Data is read from the PCA9557 registers using
Read and Receive Byte transfers (see Figures 14 and 15).
1 2345 6 78 9
SCL
slave address
command byte
data to port
SDA S 0 0 1 1 A2 A1 A0 0 A 0 0 0 0 0 0 0 1 A
start condition
R/W acknowledge
from slave
acknowledge
from slave
WRITE TO
PORT
DATA 1
DATA OUT
FROM PORT
Figure 12. WRITE to output port register
AP
acknowledge
from slave
DATA 1 VALID
tpv
SW00797
1 2345 6 78 9
SCL
slave address
command byte
data to register
SDA S 0 0 1 1 A2 A1 A0 0 A 0 0 0 0 0 0 1 1/0 A
start condition
R/W acknowledge
from slave
acknowledge
from slave
DATA
Figure 13. WRITE to I/O configuration or polarity inversion registers
AP
acknowledge
from slave
SW00798
slave address
acknowledge
from slave
S 0 0 1 1 A2 A1 A0 0 A
R/W
acknowledge
from slave
slave address
acknowledge
from slave
acknowledge
data from register from master
COMMAND BYTE
A S 0 0 1 1 A2 A1 A0 1 A
R/W
at this moment master-transmitter
becomes master-receiver and
slave-receiver becomes
slave-transmitter
DATA
A
first byte
data from register
no acknowledge
from master
DATA
last byte
NA P
2001 Dec 12
Figure 14. READ from register
9
su01052
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