I²C expansion board

Goal of the project

The goal of this project was to build a I²C controlled interface board, which can be used to access LEDs and/or switches. The advantage of this expansion board is you gain a lot of free I/O pins on the K8051 itself. Only two connections are required for the I²C bus. With these two connections you can control up to 64 digital channels.

A requirement was to add some system to use multiple of these boards in a master/slave configuration. All I²C chips have their own addresses: A part of each address can be chosen by setting one or more jumpers. This jumper functionality had to be foreseen on the expansion board.

Last but not least: we had to write a software library to access the I2C bus. We wrote this library in Assembler. Higher programming languages were not allowed for the project.