I have developed a general perpose shield that adds an extra ATMega328(info.protoneer.com/2
) to your setup. Currently I program the secondary
MCU with the ArduinoISP sketch. This works fine but I would like to add a USB port to it so you can program and send serial commands independently to the secondary MCU shield.
The ATMega32U4 would work well for this and because the Leonardo is based on it,it would add full compatibility for my shield.
What would be the bare minimum components needed to make a board that is Leonardo compatible?