{"id":468,"date":"2011-11-25T20:24:29","date_gmt":"2011-11-25T18:24:29","guid":{"rendered":"http:\/\/tomashg.com\/?p=468"},"modified":"2012-02-15T15:57:53","modified_gmt":"2012-02-15T13:57:53","slug":"sp-button-pad-controller-act-ii-adventures-in-the-avrland","status":"publish","type":"post","link":"https:\/\/tomashg.com\/?p=468","title":{"rendered":"SP Button Pad Controller ACT II (adventures in the AVRland)"},"content":{"rendered":"

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Since things didn’t work out as smoothly as I expected, no proper information on the net, nor anyone wrote a library for it; spent few sleepless nights trying to figure it out,\u00a0things\u00a0seemed doomed.. I decided to contact Spark Fun for more technical info. Within an hour they answered me, was really helpful but tried to answer as much as he could and gave me a fresh set of ideas.<\/p>\n

After going through the schematics<\/a> of the board and its original firmware code<\/a>, I realized that the USB board has two ATmega328<\/a> micro-controllers. As opposed to the ISP board that has only one that controls the LED and button matrix . Basically the USB board acts as an ISP board with a built in “Arduino” to control it. So the idea was to burn an Arduino bootloader onto the Master controller and just use it as an Arduino, easy I thought.<\/p>\n

Not so much as it \u00a0turned out. I needed an AVR\u00a0programmer, which\u00a0of course\u00a0I did not have. But fear not, to the rescue came the Arduino Mini Pro<\/a> boards I got earlier, they can be rigged and used as programmers<\/a> (sounds like a fun party). Furthermore, I had to do a small dirty trick to disable reset on the Mini Pro, basically put a\u00a0capacitor\u00a0between the Reset and Ground pins. But none of the\u00a0boot loaders\u00a0worked properly and I was getting desperate again. Also the board lost its USB API so I tried to re-compile and restore its original firmware. \u00a0And so it struck me, why not just modify the existing firmware to send midi data directly whenever a button is pressed and also light up that button. Of course this would be the optimal solution\u00a0as I would not need a driver application to run the whole thing, just route the MIDI traffic through to my applications.<\/p>\n

After more than 5 days of less than 3 hours sleep per day, endless testing, trial by error and just\u00a0aimlessly\u00a0poking around I finally get a MIDI signal and a led on! Victory! The firmware still needs a lot of optimization but at least now I know I’m on the correct track, and can finally get a good night’s sleep without commands and diagrams on my mind!
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