I came across a problem that demands a solution that I can't figure out how to implement, if possible at all.
And as I can't quite explain it directly, I'll explain what it should work as and hopefully someone can let me know if this is possible.
I have a project with an "arduino" running from batteries. In the final version of the project , it will be just an atmega chip, probably an attiny85.
It will be extremely power conservative, and it will sleep most of the time. It will be handling some stuff, part of it is monitoring and managing the voltage from a 12v lead acid battery and some connected devices. This battery will have 3 possible states. Discharged, charging, and normal state. I need the arduino to run only on normal state. Above 11.4v and below 12.9v
Is there a passive way of driving an interrupt from a voltage change? Something like wake up the chip when the voltage lowers from the "charging" voltage (12.9v) or when the voltage "rises" from the discharged voltage (11.4) ?
Something that consumes no power or consumes on the few microAmps range?