Electronic – Communication between microcontroller and separately powered PCB


On one board I have a microcontroller with one power supply and on another I have a Flip Flop with a separate power supply. I want to connect a pin of the microcontroller to the reset pin of the flip flop. Can I just put a wire accross or does it need more than that? I was going to do that but now I'm not sure that would work because it wouldn't be a complete circuit and the two boards may not have quite the same ground levels. The two boards have to have separate power supplies because the board with the DSP is premade and the power comes from the mains. Thanks

Best Answer

A single wire may or may not work - check to see if your boards have a common-enough ground. You may get lucky and it will be just fine (since both boards will be connected to the mains ground, at least in some way). At the very least, you can probably run two wires - one to tie the two grounds together and another for the data. If for some reason you can't have a common ground, you can look into optoisolators.