I have a project that is using a grounding signal to trigger a digital input, but I also need an automotive 12v signal to trigger the same input wire as if it were being grounded. It doesn't need to necessarily need to be the same digital input pin, but the signal will be coming in on the same wire. So my logic table would be something like:
|Input signal||voltage at digital pin||Logic|
I am using a 7805 to convert the automotive 12v into 5v for the 328p pro mini 5v 16mhz Arduino. Does someone have an idea of how to best design a circuit to do this?