Description:
This tiny little board does all of the neat-o tricks that you're familiar with: 4 channels of 10-bit ADC, 5 PWM pins, 12 DIOs as
well as hardware serial connections Rx and Tx. Running at 16MHz and 5V, this board will remind you a lot of your other favorite for Arduino-compatible boards but this little guy can go just about anywhere. There is a voltage regulator on board so it can accept voltage up to 12VDC. If you're supplying unregulated power to the board, be sure to connect to the "RAW" pin on not VCC.
This latest revision corrects the silk error from the last version of the board so that pin 14 is correctly labeled. We've also
added a PTC fuse and diode protection to the power circuit and corrected the RX and TX LED circuit.
Features:
●ATMega 32U4 running at 5V/16MHz
●Supported under for 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
 
Resurces:
1. Pro Micro USB(ATmega32U4) Hookup Guide
2. Getting Started with the Arduino Leonardo, Leonardo ETH and Micro