SAMD21 M0, 32-bit ARM Cortex-M0+ Development Board (Arduino M0 Compatible)
Overview
The RobotDyn SAMD21 M0 is the shield-compatible version of the SAMD21 M0-Mini. Same chip (SAMD21G18), same clock (48 MHz), same 256 KB flash and 32 KB SRAM — but in the Arduino UNO R3 form factor, so you can stack standard shields on top.
This is essentially a clone of the Arduino M0 (or Arduino Zero, depending on which board the firmware targets), giving you 32-bit ARM performance with the convenience of UNO-shield compatibility.
When to Choose This Over the M0-Mini
- You want to stack existing UNO shields (ethernet, motor, sensor shields, etc.)
- You’re prototyping on a breadboard but want to migrate to a project with shields later
- You need the larger PCB area for hand-soldering modifications
For all other cases, the M0-Mini is smaller, cheaper, and electrically identical.
⚠️ Shield Compatibility Caveats
The SAMD21 is 3.3 V only — many UNO shields designed for 5 V Arduinos may:
- Read your 3.3 V output as a valid HIGH (works fine, e.g., relay shields, motor shields with logic input)
- Drive 5 V into the SAMD’s pins (will damage the MCU — e.g., level shifters that output 5 V back)
Check each shield’s electrical requirements before stacking. Look for “3.3 V compatible” or “Zero compatible” in the shield’s documentation.
Pinout
Standard Arduino UNO R3 pinout, plus:
- DAC output on pin A0
- SWD debug header (4-pin) for use with ST-Link or Atmel-ICE
Programming
Same as the M0-Mini — install the Arduino SAMD Boards core, select Arduino M0, upload over native USB.
Related Products
- SAMD21 M0-Mini — Pro Mini-style compact version
Documentation
- Pinout PDF — coming soon
- Shield compatibility list — coming soon