IExpender-Pcb.png, nov. 2016

IExpender : Version 30/09/2014

When playing electronics with microcontrollers, you sometimes need to manage a lot of inputs (sensors or buttons).

Instead of using a bigger controller to have more IO ports, it is better or simpler to add extra components to it.

This piece of hardware, based on simple logic chips, uses 10 pins (8 bits for data and 2 bits for control) to manage 32 inputs.

In my case, I need this to connect 32 buttons to an arduino board.


Usage and restrictions

  • 4 banks of 8 bits. Each bank handles 8 inputs,
  • Bank number is selected with 2 control signals (signals A and B on 74LS138),
  • The board can be extended to manage 64 inputs (4 other 74LS541 must be added)

Enjoy !