Smart Home Automation Forum

some of KC868-A16 V1.5 hardware version, PCF8574 address is changed. (if you have seen PCB is V1.5 and have GREEN label, you need to use new address value)
before is :

Relay_IIC_address 0x24
Relay_IIC_address 0x25

Input_IIC_address 0x21
Input_IIC_address 0x22

new is :

Relay_IIC_address 0x3C
Relay_IIC_address 0x3D

Input_IIC_address 0x39
Input_IIC_address 0x3A

[attachment=1256]

if you don't know your PCF8574 address, you can use this "I2C scan" arduino IDE source code to scan address, it will print value by serial port.

here is source code: [attachment=1257]

FYI, one address was different for my board (hardware rev 1.5) thus failing to initialize: 3B, instead of 3A.

Code:
I2C scanner. Scanning ...

Found address: 57 (0x39)

Found address: 59 (0x3B)

Found address: 60 (0x3C)

Found address: 61 (0x3D)

Found 4 device(s).

it's normal, some times different chip have different I2C address.

admin

LTDU

admin