Arduino Micro without headers

The Arduino Micro features a built-in USB connection that makes the Micro recognizable as a mouse or keyboard. The Micro is a microcontroller board based on the ATmega32U4, developed in collaboration with Adafruit. It has 20 digital input/output pins, of which 7 can be used as PWM ...The Arduino Micro features a built-in USB connection that makes the Micro recognizable as a mouse or keyboard.

The Micro is a microcontroller board based on the ATmega32U4, developed in collaboration with Adafruit. It has 20 digital input/output pins, of which 7 can be used as PWM outputs and 12 as analog inputs, a 16 MHz crystal oscillator, a micro USB port, an ICSP header, and a reset button. It includes everything needed to support the microcontroller; simply connect it to a computer with a micro USB cable to get started.

It has a form factor that allows it to be easily placed on a breadboard. The Micro board is similar to the Arduino Leonardo in that the ATmega32U4 has built-in USB communication, eliminating the need for a second processor. This allows the Micro to appear to a connected computer as both a mouse and keyboard, in addition to a virtual serial/COM port.

It also has other effects on the board's behavior, which are detailed on the Getting Started with the Arduino Micro page.