I know that putting I/O pins into the output state makes them low resistance and that you can burn out the board easily while they are in this state but hear me out.
I have a small relay… it’s a rather good one for arduinos because it requires 17mA to toggle and I’ve tested it on a pathetic tiny board and it works just fine. Any I/O pin will flip it on and off.
Now I have a version of this relay that has 2 relays on 1 board and a pin header for 2 I/O inputs. I am using this setup to simulate a DPDT relay by activating both relays at the same time.
Now I could take 1 I/O and just split it to both inputs but that will over-draw on current so I want to use 2 I/O pins to do it. However I have only 1 wire with which I can do this. I don’t want to get into the reasons why I can’t use 2 wires. I just have to use 1. So the question is, can I gang 2 I/O pins together and run them through this 1 wire and then split again at the relay to the 2 inputs so that I get 2x the current? I will never be toggling the I/O pins separately. They will always turn on and off at the same time (within clock cycle execution time that is) and I will never hold them on for more than about 20 seconds.
I figure, as long as the pins are at the same voltage and the load is drawing current, the arduino shouldn’t be able to short out for more than a couple hundred nS or however long it takes between turn-on signals, right?