
PCA9675
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NXP B.V. 2011. All rights reserved.
Product data sheet
Rev. 2 — 3 October 2011
13 of 34
NXP Semiconductors
PCA9675
Remote 16-bit I/O expander for Fm+ I2C-bus with interrupt
8.3 Reading from a port (Input mode)
All ports programmed as input should be set to logic 1. To read, the master
(microcontroller) first addresses the slave device after it receives the interrupt. By setting
the last bit of the byte containing the slave address to logic 1 the Read mode is entered.
The data bytes that follow on the SDA are the values on the ports.
If the data on the input port changes faster than the master can read, this data may be
lost.
Fig 14. Write mode (output)
A5 A4 A3 A2 A1 A0
0
A
SA6
slave address
START condition
R/W
acknowledge
from slave
002aab632
P
06
1
P
07
data to port 0
A
acknowledge
from slave
12345678
SCL
9
SDA
A
acknowledge
from slave
write to port
data output from port
tv(Q)
P05
data to port 1
data A0 and B0 valid
P16 output voltage
Itrt(pu)
IOH
td(rst)
P16 pull-up output current
INT
P
04
P
03
P
02
P
01
P
00
P
17
P
14
P
13
P
12
P
11
P
10
1
P16
P
15
tv(Q)
data A0 and B0 valid
P05 output voltage
Itrt(pu)
IOH
P05 pull-up output current