One-Input Numeric Keypad

This is a 12-key numeric keypad for use in a range of microcontroller projects. It has the advantage that you only need one analogue input to interface it: The 12-key Numeric Keypad that interfaces to a single analogue input. It's on a small 1.2 x 1.6" (30 x 40mm) PCB, and I've also built a demo circuit to show how to use it. Introduction Microcontroller projects often need a numeric keypad, and a…