I am building a programmable car ignition system based around a microcontroller. I would like to ensure that the system reboots itself should the micro freeze, rather than stop the engine in the fast lane. The internal watch dog timer (WDT) won't work if the micro locks up. My thoughts are to monitor the micro output pin that drives the ignition coil via an IGBT using a missing /stopped pulse detector to momentarily disconnect and reapply the power to unfreeze the microcontroller. As this output is only available once the engine is running I need to work out a way to inhibit this rebooting while starting the engine. That is the part that is giving me a headache as I'm trying to keep this as simple as possible and definitely only in hardware.
Grateful for any ideas
David
Grateful for any ideas
David