This is probably basic, but I really want to avoid damaging my $300 PCB. The PCB is a 5V device and it takes input via button presses. The button simply connects common to the input.
How do I simulate that button press with the arduino? And do I need to test the PCB first to clarify anything about how it works?
my guess would be:
connect pin0 to the PCB input
pinMode(0, OUTPUT); // set pin to output
digitalWrite(0, LOW); // turn on
PS. they will be sharing a 5V supply, if that is relevant.