Datasheet

PCA9551_8 © NXP B.V. 2008. All rights reserved.
Product data sheet Rev. 08 — 31 July 2008 10 of 26
NXP Semiconductors
PCA9551
8-bit I
2
C-bus LED driver with programmable blink rates
7.4 Bus transactions
Fig 11. Write to register
0 AS
slave address
START condition R/W acknowledge
from slave
002aac507
0 0 AI 0 B2B1B00
command byte
A
acknowledge
from slave
12345678SCL 9
SDA DATA 1 A
write to register
data out from port
t
v(Q)
acknowledge
from slave
DATA 1 VALID
data to register
1 0 0 A2 A1 A01
Fig 12. Read from register
1 0 0 A2 A1 A0 0 AS1
START condition R/W
acknowledge
from slave
002aac508
A
acknowledge
from slave
SDA
A P
acknowledge
from master
data from register
DATA (first byte)
slave address
STOP
condition
S
(repeated)
START condition
(cont.)
(cont.)
1 A
R/W
acknowledge
from slave
slave address
at this moment master-transmitter becomes master-receiver
and slave-receiver becomes slave-transmitter
NA
no acknowledge
from master
data from register
DATA (last byte)
command byte
0 0 AI 0 B2 B10B0
Auto-Increment
register address
if AI = 1
1 0 0 A2 A1 A01
Remark: This figure assumes the command byte has previously been programmed with 00h.
Fig 13. Read Input Port register
1 0 0 A2 A1 A0 1 AS1
START condition R/W acknowledge
from slave
002aac509
A
acknowledge
from master
SDA NA
read from
port
data into
port
P
t
h(D)
data from port
no acknowledge
from master
data from port
DATA 4
slave address
DATA 1
STOP
condition
DATA 2 DATA 3 DATA 4
t
su(D)