I have an interesting question, which I really don't know how to do it or it is even possible.
Problem: I want to start a computational unit (ex: raspberry pi) when the engine starts. If the engine goes down, it should close itself but a soft close from the software.
Need: I should detect the status of the engine.
Constraints: I can not attach anything to the engine or ignition key circuit. I only have the power line from the battery. The power line does not close even if the engine is not working.
Question: Can I detect the status of the engine from the power line? How?