This Pro Micro compatible board is quite similar to the Pro Mini, except that it has an ATmega32U4 on board. The 32U4 has built-in USB transceiver, thus eliminating the need for a secondary processor, and allows the Pro Micro to appear as a mouse and keyboard on connected computer.

Specifications:

• ATmega32U4 running at 5V/16MHz
• Supported under Arduino IDE v1.0.1
• On-Board micro-USB connector for programming
• 4 x 10-bit ADC pins
• 12 x Digital I/Os (5 are PWM capable)
• Rx and Tx Hardware Serial Connections
• Over current protected
• Reverse polarity protected
• DC input 5V up to 12V
• On board Power and Status LEDs
• Size33mm x 18 mm x 6mm