This is a retired product, but fear not as there is a newer, better version available: DEV-12640
images are CC BY-NC-SA 3.0
Replacement: DEV-11098. We've revised this board to correct the silk and LED errors. We've also added a PTC fuse and diode protection circuit. This page is for reference only.
Description: Here at SparkFun, we refuse to leave 'good enough' alone. That's why we're adding to our line-up of Arduino-compatible microcontrollers once more! 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 of the neat-o 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, this board will remind you a lot of your other favorite Arduino-compatible boards but this little guy can go just about anywhere.
Note: There are two minor errors on this board which shouldn't affect your overall project to any great degree but are helpful to know about. Digital Pin 14 is mis-labeled as Pin 17 on the silkscreen. Also, the Tx and Rx LEDs are pulled to ground instead of VCC.
Note: This board uses what's known as the "diskloader" bootloader, this is presumably the same bootloader used by the Arduino Leonardo. This bootloader is still in its infancy so expect some glitchiness here and there. Also, because it works over HID you will need to install some drivers so that your computer will recognize it. A "readme" file in the driver pack below explains how to do this.
Note: See the GitHub link below for support with the Arduino IDE.