I’m trying to create a system that essentially is connected to a power adapter running at 3v being sent to the Vin port, and a power bank supplying 5v to the USB jack (whilst having the power bank charging)
Essentially, I have the actual Vin pin on the arduino board connected to a small voltage divider circuit which sends the divided voltage into an analog in pin. Essentially what im trying to do is on the event of a power outage i want the arduino to detect the fact that the power has gone out and start running a secondary goto loop section of code that would essentially act as a “low power mode program” embedded into the main program. what i’m wondering if while the arduino is being powered via the USB port, i want to know whether i can send a voltage less than 3v into the Vin port while its being powered by the USB port, keeping in mind of course that at ~5-6v it the arduino board automatically switches from the Vin port to the USB port.
I’ve been doing a lot of research and digging online but I’ve found nothing. So is what i’m describing safe for the arduino or will it harm it in some way?