I never cleaned it up for release, but if you email me I could send through some interesting bits of it. I2C and the peripheral we were dealing with is quite s

I never cleaned it up for release, but if you email me I could send through some interesting bits of it. I2C and the peripheral we were dealing with is quite stateful, and writing the access code in a synchronous fashion wasn't possible due to overrunning other constraints. It seemed like a good idea at the time. The sibling comment has it pretty right... it would probably have been quicker in the end to go to an RTOS. That said, I'm still fairly proud of the I2C state machine that runs in the interrupt handler– it was completely separate from the protothread code that layered over the top. It's in a few microcontrollers in products we do, the funkiest is the smallest standard AVR package you can get, which imitated an obsolete tiny I/O expander chip we had to replace on a 6mm wide PCB. That was using I2C slave mode, but we could then run the entire sensor interfacing on that board rather than using a separate micro.