PCA9551 Philips Semiconductors, PCA9551 Datasheet - Page 9

• Manufacturer Part Number: PCA9551
• Description: 8-bit I2C LED driver with programmable blink rates
• Manufacturer: Philips Semiconductors

1. This figure assumes the command byte has previously been programmed with 00h.
Philips Semiconductors
Bus transactions
NOTES:
2004 Oct 01
S
8-bit I
READ FROM
FROM PORT
DATA INTO
1
REGISTER
DATA OUT
WRITE TO
PORT
PORT
1
SDA
SDA
SCL
2
0
slave address
C LED driver with programmable blink rates
start condition
0
S
A2
1
start condition
1
S
A1
2
1
1
A0
acknowledge
from slave
3
0
slave address
1
R/W
0
4
0
0
slave address
DATA 1
A
A2
5
0
0
A1 A0
6
A2
0
7
A1 A0
0
R/W
0
8
AI
t
R/W
ph
Figure 12. READ input port register
A
acknowledge
from slave
9
0
1
Figure 11. READ from register
Figure 10. WRITE to register
B2 B1
0
A
acknowledge
from slave
0
acknowledge
from slave
DATA 2
B0
0
command byte
A
AI
at this moment master-transmitter
becomes master-receiver and
slave-receiver becomes
slave-transmitter
9
data from port
S
0
DATA 1
1
DATA 3
B2
1
B1
slave address
0
B0
0
A
A2 A1 A0
acknowledge
from slave
t
ps
A
acknowledge
from master
acknowledge
from slave
R/W
1
data to register
A
data from port
DATA 1
DATA 4
data from register
DATA 4
last byte
data from register
DATA
no acknowledge
from master
first byte
DATA
t
pv
PCA9551
Product data sheet
A
acknowledge
from slave
no acknowledge
from master
auto-increment
register address
if AI = 1
DATA 1 VALID
NA
SW01082
acknowledge
from master
NA
SW01081
SW01084
P
stop
condition
P
A