SAMD21 Breakout

An ATSAMD21G18A-AU breakout with the physical layout lifted from the Arduino MKR Zero. It is a bare-metal SAMD21 on headers, no built-in programmer and no extra fluff. Bring your own power, SWD and USB. Program it like an Arduino M0 once you burn a bootloader.

What's on the board

• ATSAMD21G18A-AU in a TQFP-48 hand-solder package
• AMS1117-3.3 regulator, so 5 V or USB gives you 3.3 V
• Micro-USB port for power and programming
• Two 2.54 mm header rows breaking out the full pinout
• 10-pin SWD header plus a 32.768 kHz crystal

Getting it running

Power the board from 5 V or USB and the AMS1117 makes 3.3 V. For Arduino-style use, burn the Arduino M0 bootloader via SWD once, then the USB port appears as a serial device you can flash from the IDE. Alternatively, target the `mzeroUSB` board in PlatformIO with the ATMEL SAM core.