The Pro Micro is similar to the Pro Mini except with an ATmega32U4 on board.
The USB transceiver inside the 32U4 allows us to add
USB connectivity on-board and do away with bulky external USB interface.
This tiny little board does all work for Arduino 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,
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.
ATMega 32U4 running at 5V/16MHz
Supported under for Arduino IDE v1.0.1
On-Board MINI 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