I intend to have both an Arduino Nano and an Uno connected to a PC via the on-board USB ports, but have them inter-connected with wires from one's GPIO pins to the other's (one reads the status of the other's pins). I've read that having two Arduinos communicate with each other requires them to share a common ground, so am not sure if this will work at all (the common power source in the PC may serve as the common ground, I'm not sure).
As some background, I would like the Nano to serve as an EEPROM programmer and have the Uno connected as a logic analyser to help debug the EEPROM programmer, both using serial to communicate with the PC in real-time.
How should I set up the Arduinos and power supply to make this possible in a safe way?
