Mini SAM is a project to design and build a LEGO® minifigure sized development board based on the Atmel® | SAM D21E ARM® Cortex®-M0+ based microcontroller incorporating as many additional features as possible within the size constraint. Along with the physical board design and layout, software and firmware was developed to allow programming using the Arduino IDE. The board features an ESD protected micro USB port for programming, power, and serial communication back to the Arduino IDE Monitor. Included on the board are a simple LED, a WS2812B Red/Green/Blue LED, a builtin button, a reset button, and the SWD Cortex programming/debugging port. In addition, a 32.768kHz crystal is included to support the builtin real-time clock available in the SAM D21E chip. I2C pull-up resistors and analog reference decoupling/filtering capacitors are also included for convenience. Around back are solder pads for SMT 11-Pin .1″ spaced headers ready for insertion into a breadboard.
The printed circuit board is as close to the size of a LEGO® minifigure as could be made, which makes it 0.95 inches wide and 1.55 inches tall. All design files are available on Github and support open-source hardware (OSH) initiative.
The board features the beautiful 1980’s spaceman rocket around the planet logo as well as Emmet’s badge from The LEGO® Movie. As much of the original LEGO minifigure shape has been replicated and kept in the PCB design, but some limitations to manufacturing required some compromises. Look for additional shapes in the future, but for now, the basic minifigure without any head covering is the basis.
The main design goal was to produce a board on which any hobbyists could build and develop. As such, the majority of components are solder-able by a steady hand, with only a few items, such as the 0603 LED and micro USB port, requiring some extremely steady hands. However, use of a solder paste stencil and a hot air station is highly recommended.