Seeed Studio XIAO SAMD21 Cortex M0+ (Seeeduino XIAO)

Seeed Studio XIAO SAMD21 is the smallest board in the Seeeduino family, built around the Microchip SAMD21G18 chipset. It's a native Arduino IDE-compatible board packed into a 21 x 17.8mm footprint, backed by a large library of free courses, tutorials, and community projects that make it an easy platform to learn on, and powerful enough to grow into wearables, IoT devices, and more advanced builds as your skills develop.

Unsoldered for Custom Builds

This is the base version of the XIAO SAMD21, supplied without headers soldered on. That makes it a better fit if you're planning to solder it directly into a custom PCB, use it in a low-profile or space-constrained enclosure, or simply prefer to choose your own header type and orientation. If you'd rather skip the soldering step entirely, we also stock a pre-soldered version, ready to plug straight into a breadboard.

Compact Form Factor and a Growing Ecosystem

At just 21 x 17.8mm, the XIAO SAMD21 set the standard for miniature development boards when it first launched in 2019. It's natively compatible with the wider XIAO add-on ecosystem, including expansion boards, sensors, displays, connectivity modules, and actuators, covering everything from Grove modules and CAN-Bus to LoRa, vision sensors, GPS, and more. Whatever the scope of your project, there's likely a compatible module to support it.

Specifications

Applications

• Learning and education (Arduino, MicroPython, basic electronics and prototyping)
• Wearable devices (health monitoring, interactive clothing, compact fitness trackers)
• IoT and sensor projects (environmental monitoring, data collection, smart home sensors)
• Space-constrained mini Arduino projects (miniature robots, portable devices, embedded control systems)
• Rapid prototyping and proof-of-concept builds
• HID devices (DIY keyboards, USB-to-TTL host mode, etc.)

Pinout

Resources

• Full setup guides, pinout diagrams, and project examples on the Seeed Studio Wiki
• Browse our full range of XIAO Expansion & Breakout Boards
• Prefer plug-and-play? See the pre-soldered Seeed Studio XIAO SAMD21

This product can be found here:

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• Seeed Studio XIAO Boards