Like its brother the Leonardo board, the Arduino Micro has one microcontroller with built-in USB. Using the ATmega32U4 as its sole microcontroller allows it to be cheaper and simpler.

supported Arduino boards: Leonardo, Micro and ProMicro (ATmega32U4, 5V, 16MHz) 4 analog axes + 1 for an optical encoder, 2 FFB axes ... while firmware for Arduino ProMicro (with replacement pinout) is ...

In the Leonardo, an op-amp between the ATmega pin and the led means that loading is minimal and the pin can easily be used as an Arduino input. This buffer is missing on the Micro, which means even ...