I had previously posted this message, got some helpful information and it appeared to work exactly 1 time.
I am attempting to have Uno 1 to control code on Uno 2. I have a ground wire going from Uno 1 to Uno 2. On Uno 1, I have set up pin 8 to OUTPUT and I've connected pin 8 on 1 to pin 2 on Uno 2. On Uno 2, I have setup pin 2 to INPUT_PULLUP.
When I want the code to run Uno 2, I digitalWrite pin 8 to HIGH or LOW depending what I need to happen. I have confirmed that pin 8 on Uno 1 goes HIGH or LOW as required.
I believe that when pin 8 on Uno 1 goes HIGH, pin 2 on Uno 2 should go LOW but it doesn't, pin 2 on Uno 2 remains HIGH regardless of the status of pin 8 on Uno 1.
I'm obviously missing something but I don't know what it is.
Any suggestions would be appreciated. Thank you.