Datasheet

PCA9555_8 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 08 — 22 October 2009 6 of 34
NXP Semiconductors
PCA9555
16-bit I
2
C-bus and SMBus I/O port with interrupt
6. Functional description
Refer to Figure 1 “Block diagram of PCA9555”.
6.1 Device address
6.2 Registers
6.2.1 Command byte
The command byte is the first byte to follow the address byte during a write transmission.
It is used as a pointer to determine which of the following registers will be written or read.
Fig 8. PCA9555 device address
R/W
002aac219
0 1 0 0 A2 A1 A0
programmable
slave address
fixed
Table 4. Command byte
Command Register
0 Input port 0
1 Input port 1
2 Output port 0
3 Output port 1
4 Polarity Inversion port 0
5 Polarity Inversion port 1
6 Configuration port 0
7 Configuration port 1