SAM D21-based development boards have been around for several years now, like the Arduino Zero, Microchip ATSAMD21-XPRO, and SparkFun RedBoard Turbo, to name a few. Now, a new pair of SAM D21 boards has been spotted on the web that look identical, and share the same features, only they have different branding etched onto the back.
Electrodragon has listed a WeMos SAMD21 Mini Development Board ($14.50), while AliExpress features a RobotDyn SAMD21 M0-Mini ($9.99), and the same WeMos board, only couple bucks cheaper ($7.05). Regardless of the nomenclature, the boards’ specs are identical, and are outfitted with Microchip’s ATSAMD21G18 Arm Cortex-M0+ MCU (32Kb of RAM/256Kb of Flash), a micro USB port (power/programming), and 2X 14-pin headers with 19X digital I/O (12X PWM), 6X analog I/O, with 3.3V logic level.
Rounding out the feature set is a 6-pin ISCP connector (programming), power/Tx/Rx LEDs, and button. The boards have a power input of 5V (via micro USB or VIN), a power output of 3.3V (@ 800mA), and a consumption of 3.3V (@ 220mA). There is also an embedded debugger, which provides a full debugging interface, and a virtual COM port that can be used for device or bootloader programming.
There is virtually no documentation from the respective companies these SAM D21 development boards, so it’s unknown if they include any differences other than pricing. That said, GitHub user BLavery has tested the RobotDyn SAMD21 M0-Mini, giving users more details about the board, and has uploaded documentation, schematics, and firmware for those interested.