Produktdetails
The original XIAO formula, now with fewer arguments about running out of pins. The SAMD21 Plus keeps the tiny 21 × 17.8 mm footprint, then adds 16 extra SMD GPIOs, onboard Li-ion battery management and proper Reset and Boot buttons.
Why You Want It
You get the friendly, well-supported SAMD21 platform in a board small enough for wearables, compact robots and custom carrier boards. Native USB makes it particularly handy for keyboards, macro pads, MIDI controllers and other projects that enjoy pretending to be a USB device.
Standard or Plus?
The standard XIAO SAMD21 is the simpler choice if its usual header-row I/O is enough. Plus adds 16 GPIOs on 1.27 mm SMD castellations and onboard Li-ion charging. The extra connections need SMD soldering or a suitable custom carrier; fitting the two 7-pin headers does not bring every Plus GPIO onto a breadboard.
Setup and pinout
Use Seeed’s setup guide and standard/Plus pin map before wiring. For Arduino, follow the Plus-specific Blink instructions and select XIAO M0 Plus rather than copying the standard board example. Check the board support for your chosen firmware before building around the extra pads.
Still choosing between processors? Read our XIAO RP2040 Plus vs SAMD21 Plus comparison, then check the matching pin map.
Specifications
- MCU: Microchip ATSAMD21G18A, 32-bit ARM Cortex-M0+ at up to 48 MHz
- Memory: 256 KB Flash and 32 KB SRAM
- GPIO: 27 digital I/O, of which 11 support analogue input; analogue functions share these pins
- Interfaces: 2× I²C, 1× UART, 1× SPI, 1× I²S and 1× DAC
- Extra I/O: 16 additional GPIOs on 1.27 mm SMD castellations
- USB: USB Type-C with native USB device support
- Battery Management: Onboard PMIC with Li-ion charging and BAT-to-3V3 backflow protection
- Onboard Controls: Reset button and Boot button
- Indicators: Programmable WS2812 RGB LED and charge LED
- Input: 5 V by USB Type-C or BAT input
- Dimensions: 21 × 17.8 mm (still properly tiny)
- Operating Temperature: -40°C to 85°C
- Software Support: Arduino, PlatformIO, MicroPython, CircuitPython, TinyGo, Zephyr and more
What's in the Box*
- 1× Seeed Studio XIAO SAMD21 Plus
- 2× 7-pin headers
Disclaimer
*Battery and USB cable are not included. It may have gained 16 extra GPIOs, but it has not gained the ability to label your jumper wires for you.
Still Here?
Either you are counting GPIOs twice (respect) or your current board has finally run out. Add one to the bench and give the next tiny project some room to grow.