Capacitive Touch Matrix Numpad For an Atmega328p

Files

src/* source code
pcb/* board & schematics

Technical Background

Excellent technical description by Viacheslav Slavinsky:

http://sensi.org/~svo/capsensor/index.en.html
QMatrix Whitepaper:

http://ww1.microchip.com/downloads/en/DeviceDoc/qmatrix_white_paper_100.pdf

PCB Design guidelines

Moisture Tolerant QTouch Design:

http://ww1.microchip.com/downloads/en/Appnotes/doc42017.pdf
QTouch Schematic and Layout Checklist:

http://ww1.microchip.com/downloads/en/Appnotes/Atmel-42094-QTouch-Schematic-and-Layout-Checklist_ApplicationNote_AT02259.pdf