STM32F042F6P6 MCU with internal oscillator SWD header for easy debugging (not populated by default) Dual USB port (Vertical or Horizontal) with breakout pin header for USB header I2C Screen connections for 1.3" display with jumpers on back for slecting which pins (1 or 2) are power and ground EN11-style click encoder support Reset/kill button 3 GPIO pin header 1 on-board Neopixel with data line broken out for expansion