Hi All,

I'm doing some sort like reverse engineering with mcu board.

I was given the diagram using AT89C55WD mcu which connect to two i2c I/O expander (PCF8574)

- SCL connected to P3.5
- SDA connected to P3.4

It seems like using I/O port to build a i2c port, because AT89C55WD doesn't have an i2c buffer.

Does anyone has try this method and please give me an idea how to built it.

PS: I've seen the program that build the serial com port using I/O port but not the i2c port.

Thanks

Parif