The Microchip ATSAMD21 family is one of the most popular ARM Cortex M0+ microcontroller families on the market. They have made their way into many projects due to their low cost, high performance, and low power usage. This tiny, postage-stamp sized development board is quite possibly the smallest dev board with a Cortex M0+! With 256kB of flash and 32kB of SRAM, it is also one of the highest memory-per-square-inch development boards I’ve seen.
The board is designed in the mikroBUS format, allowing it to be used with a wide range of peripheral add-on boards, making prototyping with it quite easy. The 0.1″ pin headers are also breadboard friendly. A nice touch is the inclusion of a Grove connector on the bottom, which adds even more options for prototyping.
Almost all of the I/O pins are broken out — only 5 couldn’t be routed, which still leaves you with 21 available user pins. Two on-board LEDs are included, a must-have for any development board. A Microchip MIC5528 regulator is also included, allowing 5V to be used to power the 3.3V board. However, the 3.3V bus is also broken out, in case you want to power it directly (or use a lower voltage for more power savings!).
The board comes with a great PDF that details the complete pinout, as well as a full schematic. You will need a way to program it using either one of the Atmel programmers, or the new Microchip PicKit 4 or MPLAB Snap. It’s also compatible with the Arduino bootloader, so it can be programmed over serial if that is flashed.
If you need a powerful, yet low-power microcontroller for your next tiny project, this is a great choice!