Good Times, Part 2.

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One of the most fun parts of making the timer was the capacitive touch buttons. So in this post, I'm going to touch on how I did it. I might even post a little code :) ( I'm still getting the hang of this blogger thing so bare with me as I play with formatting, etc). 

The inspiration.

I've worked with mechanical buttons on past projects, and I was always less than happy with how the buttons looked, or cost, or how much effort you had to put in to "getting it right". I've spent hours on mouser or digikey looking at buttons, only to discover the datasheets didn't really give you a good grip on the aesthetics or "feel" of the mechanics. Also, the physical chassis construction work, (my least favorite part of a project), seemed to consume a disproportionate amount of effort. Touch buttons, I thought, would be easy, cheap, and I had a lot of options for how to make them look nice. I was aware of the Atmel QTouch chips, but every time I went to tack some on to one of my hobby parts purchases, they were always out of stock. Then I came across this in an Arduino forum (I don't actually own an Arduindo, but a lot of people do some clever things with them):

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1171076259 (Paul Badger)

That got me thinking, the low AVR microcontrollers are cheaper than most of the touch sensor controllers, and come in DIP form factor. It's such a simple idea, it's brilliant!. So with with a breadboard, my trusty AVR Dragon, and some aluminum foil, I experimented.

The implementation:

I didn't have this blog in mind when doing the project, so I neglected to get a good shot of the early experiments, but this one shows my test touch panel, as well as other parts of the project at various levels of completion.

My test touch panel. (also check out the finished display board, and my homemade  breadboard/6 pin isp adapter)