PCA9551 Datasheet, PDF (10/26 Pages) NXP Semiconductors – 8-bit I2C LED driver with programmable blink rates

NXP Semiconductors
7.4 Bus transactions
PCA9551
8-bit I²C-bus LED driver with programmable blink rates
SCL 1 2 3 4 5 6 7 8 9
slave address
command byte
data to register
SDA S 1 1 0 0 A2 A1 A0 0 A 0 0 0 AI 0 B2 B1 B0 A
DATA 1
A
START condition
write to register
data out from port
Fig 11. Write to register
R/W acknowledge
from slave
acknowledge
from slave
acknowledge
from slave
t_v(Q)
DATA 1 VALID
002aac507
slave address
command byte
SDA S 1 1 0 0 A2 A1 A0 0 A 0 0 0 AI 0 B2 B1 B0 A ^(cont.)
START condition
R/W
acknowledge
from slave
slave address
(cont.) _{S 1 1 0 0 A2 A1 A0 1 A}
(repeated)
START condition
R/W
acknowledge
from slave
Fig 12. Read from register
acknowledge
from slave
data from register
data from register
DATA (first byte)
A
DATA (last byte)
NA P
Auto-Increment
register address
if AI = 1
acknowledge
from master
no acknowledge STOP
from master condition
at this moment master-transmitter becomes master-receiver
and slave-receiver becomes slave-transmitter
002aac508
slave address
data from port
data from port
SDA S 1 1 0 0 A2 A1 A0 1 A
DATA 1
A
DATA 4
START condition
read from
port
data into
port
R/W acknowledge
from slave
acknowledge
from master
t_h(D)
DATA 2 DATA 3
t_su(D)
DATA 4
Remark: This figure assumes the command byte has previously been programmed with 00h.
Fig 13. Read Input Port register
no acknowledge
from master
NA P
STOP
condition
002aac509
PCA9551_8
Product data sheet
Rev. 08 — 31 July 2008
© NXP B.V. 2008. All rights reserved.
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