If anyone is interested, here is the source code for speeduino [1], megaSquirt [2] and rusEFI [3], two comparable open source ECUs.
[1] https://github.com/noisymime/speeduino/
[1] https://github.com/noisymime/speeduino/
Speeduino started as a way of getting a DIY ECU that was far cheaper than what Megasquirt offerred and it's currently about 1/3 the price. It's not on the same level for features at the moment, but I do new firmware releases every 2 months or so with more functionality etc.
Keep up the good work. I currently run/tune Megasquirt in several cars, but I’ve been waiting to give Speeduino a shot.