Hi! I am goint to experiment with a ATtiny25V controlling another device with a NPN transistor basically. I am going to control it periodically so I am going to enter sleep mode and later wake up with the watchdog timer.
The thing is that the device that I am going to control also have a main power switch, when waking up I need to be able to detect if there is any current drawn, if not then I need to enter sleep mode and when current is detected again wake up.
I guess I need to wake it up on pin state change but don't know how to do this based on if there is current drawn or not. I need this to be cheap and tiny, I don't need any accuracy at all measuring current I just need to detect if there is current being drawn if that makes sense. What components should I be looking at? It needs to handle up to 60 V 5A.
Hope I described my question well enough to let you understand what I want.
*Edit: I wonder if I could use a hall effect sensor? Perhaps for going to sleep but tricky to wake up I guess. For waking up it would require something to be powered from the device being controlled and be able to work in a wide range of different voltages, anything passive that can manage to do this?
*Edit2: To summarize my question: Is there a passive (or parasitic) way to wake up my microcontroller when the main power switches back on and that device begins to draw power?