SAMD21 MINI / Wemos D1 SAMD21 M0 Mini Development Board

SAMD21 MINI / Wemos D1 SAMD21 M0 Mini Development Board

Microchip / Atmel SAMD21 Arm Cortex-M0+ microcontroller has been around for several years and we have wrote for many boards using this microcontroller including the SAMD21 Lora Board and Minimal ATSAMD21 Board. Now, another SAMD21 development board has been shown up on Electrodragon website: the SAMD21 Mini Development Board which is sold for $14.50 on the website, but you can find it cheaper on Aliexpress.


  • MCU – Microchip ATSAMD21G18 Arm Cortex-M0+ microcontroller @ 48 MHz with 32KB data RAM, 256KB flash
  • USB – 1x micro USB port for power and programming
  • Expansion
    • 2x 14-pin headers with 19x digital I/O (including 12x PWM), 6x Analog I/O
    • 3.3V logic level
  • Programming – 6-pin ISCP connector
  • Misc – Power, Tx and Rx LED’s, button
  • Power Supply
    • Input – 5V via micro USB port or VIN
    • Output – 3.3V-800mA (However, it reads 3.3V/180mA on the silkscreen)
    • Consumption – 3.3V @ 220mA
  • Dimensions – 56.5 x 18 mm
  • Temperature Range – -40°С – +85°С

Both Wemos D1 SAMD21 M0 Mini and RobotDyn SAMD21 Mini boards appear to be identical except for the branding on the bottom of the board. There’s not a lot of documentation made available from any of the sellers but luckily, BLavery tested the board late last year and documented his experience with Arduino and CircuitPython on Github.

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Mike is the founder and editor of, an electronics engineering community/news and project sharing platform. He studied Electronics and Physics and enjoys everything that has moving electrons and fun. His interests lying on solar cells, microcontrollers and switchmode power supplies. Feel free to reach him for feedback, random tips or just to say hello :-)

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Mike Hjorleifsson

any idea where i can find the eagle or kicad footprints for this board ?

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