You can even program it to act just like a mouse, keyboard or other HID-class USB device. The Pro Micro can be programmed to emulate any USB device you could imagine. So now, when you connect the Arduino to your computer, they're connected directly over the USB bus (excuse my RAS). The Pro Micro is a tiny, Arduino-compatible microcontroller centered around an ATmega32U4 - an 8-bit AVR very similar to the ATmega328 with one huge caveat: The 32U4 comes equipped with a full-speed USB transceiver. What if you could do it with one line of code, inside the comfy confines of Arduino? Interested? Well, say hello to my micro friend: the SparkFun Pro Micro! How cool would it be if you could turn any button, joystick, sensor or other electronic gizmo into a USB keyboard and/or mouse? You could make just about any input device you want into a controller for your computer programs or games. Turn your ProMicro into a USB Keyboard/Mouse