Advantech ITA-1611 Series User Manual page 58

Please carefully read and refer to the below examples and source codes in bold.
Please download NXP Semiconductors PAC9554 spec to start programming.
1. Digital IO definition of ITA-1610:
2. Configuration sequence:
ITA-1610's GPIO is realized by a PCA9554 GPIO IC on ICH SMBUS. As a
result, configuration and access to GPIO IC should be done via accessing IO
Space of ICH SMBUS controller.
Below is the table of ICH SMBUS IO Space:
For ITA-1610, IO address of SMB_BASE in the above table is 0x400.
Refer to Chapter 3 for detailed code of accessing SMBUS IO.
SMBUS slave address of GPIO 00 - GPIO 07's PCA9554 is 0x40 (8bit address):
GPIO 00 - GPIO 07: PCA9554 0x40 (IO0 - IO7)
Below table is for PCA9554:
ITA-1611 User Manual 48