PCA9556 Philips Semiconductors, PCA9556 Datasheet - Page 7

• Manufacturer Part Number: PCA9556
• Description: Octal SMBus Registered Interface
• Manufacturer: Philips Semiconductors

Philips Semiconductors
1998 Dec 18
S
Octal SMBus Registered Interface
READ FROM
DATA INTO
0
PORT
SDA
PORT
0
1
slave address
1
A2 A1 A0
start condition
S
0
acknowledge
from slave
0
R/W
0
1
slave address
A
1
Figure 9. READ input port register via Receive byte protocol
Notes:
1. This figure assumes the command byte has previously been programmed with 00h.
2. Transfer of data can be stopped at any moment by a stop condition. When this occurs,
A2
data present at the last acknowledge phase is valid (output mode). Input data is lost.
Figure 8. READ from register via Read byte protocol
A1 A0
COMMAND BYTE
t
R/W
ph
1
A
acknowledge
from slave
acknowledge
from slave
DATA 2
A
at this moment master-transmitter
becomes master-receiver and
slave-receiver becomes
slave-transmitter
7
data from port
S
DATA 1
0
DATA 3
0
slave address
1
1
A2 A1 A0
t
ps
A
acknowledge
from master
acknowledge
from slave
R/W
1
A
data from port
DATA 4
data from register
DATA 4
last byte
data from register
DATA
no acknowledge
from master
first byte
DATA
Product specification
PCA9556
no acknowledge
from master
NA
acknowledge
from master
NA
su01051
su01052
P
stop
condition
P
A