Corvette CCM Reverse Engineering Anyone?

[spfautsch]

Oh, no no, don't take my reply the wrong way; I was in no way being critical of your code

Not taken that way at all. Just making sure we're on the same page. I wanted to push the timing envelope while servicing other devices in the main loop and that required a hardware timer.

As for your latching relay thing, I was thinking of handling it without one. I mean with a latching relay you can go to completely 0 power draw, I agree, but the power draw of an Arduino-based chip in full sleep is what, 10 microamps or something? Why not just set an interrupt for the RX pin going from low to high to wake it

Tried that and it does work. But the SD card in particular, the miscellaneous smc leds and the dual voltage regulators on the mega board draw a lot - 75ma in idle mode according to my best meter with all but uart1 (ALDL) turned off. Not worth designing my own board so I'll just flip the breaker after the CCM goes to sleep. It adds some code and component complexity but the last thing I need is to trade convenience for more parasitic draw on the battery.

As always life happened today so didn't make as much progress as I'd hoped to. Still need to resolve an occasional CCM timeout after killing the ignition (and power to the PCM).