Specs:
* 3 user leds available
* D2 via gpio
* D3 via gpio
* User led on the hammer via gpio
* 2 interrupt driven pushbuttons
* reset button
* usb powered
* usb serial port console
* usb jtag interface
* usb gadget interface
* usb host interface
* 2x10 expansion connector
* 0.1" breakout header