Toggle Nav

Seeed Studio XIAO SAMD21(Seeeduino XIAO) - Arduino Microcontroller - SAMD21 Cortex M0+ with Free Course


Seeed Studio XIAO SAMD21 is the first pioneering product of the XIAO series featuring the SAMD21 microchip and is Arduino-compatible. With its exquisite design, low power consumption, and built-in Type-C, it's perfect for TinyML, smart wearable devices, and IoT projects.

xiao samd21 free shipping



Seeed Studio XIAO SAMD21 is the first pioneering product of the XIAO series featuring the SAMD21 microchip and is Arduino-compatible. With its exquisite design, low power consumption, and built-in Type-C, it's perfect for TinyML, smart wearable devices, and IoT projects.



  • Powerful CPU: ARM® Cortex®-M0+(SAMD21G18) running at up to 48Hz, 32KB of SRAM, and 256KB of onboard Flash memory
  • Small Size: As small as a thumb(21x17.5mm) for wearable devices and small projects
  • Easy Development: Supports Arduino / Micropython / CircuitPython
  • Multiple development interfaces: 11 analog PINs, 11 digital PINs, 1 I2C interface, 1 UART interface, and 1 SPI interface
  • Designed for production: Breadboard-friendly & SMD design, no components on the back


Seeed Studio XIAO SAMD21 carries the powerful CPU-ARM® Cortex®-M0+(SAMD21G18) running at up to 48Hz. In addition to the powerful CPU, it has 256KB Flash and 32KB SRAM on board and supports the USB Type-C interface which can supply power and download code. 

It has 14 GPIO PINs, which can be used for 11 analog PINs, 11 digital PINs, 1 I2C interface, 1 UART interface, and 1 SPI interface. Some PINs have various functions, A1/D1 to A10/D10 Pins have PWM functions and Pin A0/D0 has a function of DAC which means you can get true analog signals, not PWM signals when you define it as an analog pin, that’s why 14 GPIO PINs can realize more I/O PINs and interfaces.

Except for the power LED, we add a user LED on board for your better coding experience. Usually, a dev board as small as this size will use the chip’s inner crystal oscillator for time fixing, in order to make the clock more accurate, Seeed Studio XIAO SAMD21 layouts an extra 32.768KHz to make the clock more stable.

Moreover, Seeed Studio XIAO SAMD21 is friendly to the communities for its strong software compatibilities, which supports Arduino, Micropython, and CircuitPython. Except for the software, flexible I/O allows it to speak to almost any external device. 

To provide a more smoothed learning experience for beginners, we have prepared a free course based on the Starter Kit for Seeed Xiao which contains 4 Units and 16 lessons to help you quickly get started with development boards, and then you can proceed to realize little and individual fun projects.

You can have access to the Seeed Studio Grove ecosystem by connecting it to the compatible Grove Shield for Seeed Studio XIAO. We have developed more than 400 Grove modules, covering a wide range of applications that can fulfill various needs. For example, you can make a Pocket Distance Alarm by connecting the Seeed Studio XIAO SAMD21 with a Seeed Studio Grove Shield for Seeeduino XIAO, a Grove - Circular LED, a Grove - Vibration Motor, and a Grove - Time of Flight Distance. Get started and explore the infinite possibilities of the Seeed Studio XIAO series!

By the way, we've set up a tinyml channel on our Discord server, please click to join for 24/7/365 making, sharing, discussing, and helping each other out.

We already have 5 XIAO products based on different solutions in the Xiao family, to help you better understand the differences and choose the most suitable part for your projects, please refer to the Seeed Studio XIAO Series Page.



Parameter Description
CPU ARM Cortex-M0+ CPU(SAMD21G18) running at up to 48MHz
Storage 256KB Flash,32KB SRAM
I/O PINs 14 GPIO PINs,11 analog PINs, 11 digital PINs, 1 DAC output Pin
Interface 1 I2C interface,1 UART interface, 1 SPI interface, USB Type-C interface
LEDs 1 user LED, 1 power LED, and two LEDs for serial port downloading
Reset button two reset buttons short connect to reset
Software compatibility Arduino IDE
Dimensions 21x17.5 mm



  • Wearable devices
  • Rapid prototyping (directly attached to the expanded PCB as a minimal system)
  • Perfect for all the projects that need a mini Arduino
  • DIY keyboard
  • USB development (USB to multi-channel TTL/USB host mode, etc.)
  • In a scenario where you need to read multiple mock values The DAC output


Hardware Pinout


Part List

Seeed Studio XIAO SAMD21 1
Pasters 4

Check five pieces of 7-pin male header compatible for Seeed Studio XIAO Series Board!





All the I/O pins are 3.3V, please do not input more than 3.3V, otherwise, the CPU may be damaged.


HSCODE 8543709990
USHSCODE 8471490000
EUHSCODE 8543709099
CE 1
EU DoC 1
RoHS 1
UK DoC 1



Pocket Distance Alarm - Keep 1m Away from Me -Seeeduino Xiao
A portable distance alarm that will give light and sound warning when people get into your one-meter circle.
A portable distance alarm that will give light and sound warning when people get into your one meter circle.
Pocket Distance Alarm using Grove Shield for Seeeduino XIAO, no jumper wire soldering any more!
Water Quality Station using Seeeduino XIAO that detects TDS, turbidity, and water level.
Using Seeeduino XIAO is the way to go. But one might think it is an Arduino compatible development board and might be confused about how it can be used to connect to a Raspberry Pi.
Grove Shield for Seeeduino XIAO video
[Documentation] Seeeduino XIAO HDK
This is the HDK for Seeeduino XIAO
- "Apple junior, you take charge of 1 " -- "Aye!" - "Uncle banana, you play 2" -- "Oh, no, I want 7." - “Miss Orange, please sing 5 ” -- "So sweet, I always love 5."
Get to know Wio Terminal TinyML Course #7 Machine Learning on ARM Cortex M0+ MCU Seeeduino XIAO and XIAO RP2040
The RP2040 is a 32-bit dual ARM Cortex-M0+ microcontroller integrated circuit by Raspberry Pi Foundation.
Have space constraints on your Arduino Project? Need a small Arduino board? However, there are so many small Arduino boards out there currently out there. Which one should you use?
This spider will keep quiet in the dark. But once there is light, the spider will start to vibrate, avoiding the light.
Just got your Arduino but don’t know what to do with it? No worries, we have compiled 30 cool Arduino projects to get you started!
Here's pretty much everything you want to know about Seeed Studio XIAO SAMD21. Thanks to Michel for the advanced tutorial.
This is the wiki page for this product, which will show you how to use the product, as well as details about the software and hardware.
Implementing machine learning models running on small, low-power microcontrollers and incorporating them into your projects becomes more accessible and affordable.
This course will take you step by step to learn how to use Seeeduino XIAO to learn Arduino from scratch through hands-on practice and a project-based approach.
The Grove - TDS Sensor detects the TDS (Total Dissolved Solids) levels in water which can be used to indicate the water quality. The Grove - TDS Sensor can be applied in water quality applications such as TDS meter, Well water, Aquarium, Hydroponics and etc.
How to make your own Long Range mesh sensors with the latest member of the Ripple mesh family!
A mini fireplace with burning flame surrounded by ice, to make a song of ice and fire in your home. For fans of Game of Thrones.
Vitamin D decreases susceptibility to COVID-19. Humans make Vitamin D via sun exposure. Sunkeeper measures how much sun you have absorbed.
Believe it or not, we can program this tiny board using Python, a staggering achievement of engineering.
This tutorial shows how to program Seeeduino XIAO using CircuitPython
We picked up a Seeeduino XIAO board, a tiny, SAM D21-based board with USB-C that can be programmed with Arduino or CircuitPython!
This video shows how to program capacitive soil moisture sensor and speaker using CircuitPython on Seeeduino XIAO.
Today, I will introduce a fingerprint unlocking device that can be used for the fingerprint unlocking door. This provides us with a faster and safer way to open and close doors than the traditional way.
Version 1 of my design for an RC Car using an Arduino Nano and a Seeeduino XIAO.
Programming Seeeduino Xiao is as simple as drinking a glass of water, once Arduino IDE is configured correctly.
Xiao is a mini Arduino board with the grove expansion board it enables builds prototypes and projects in an easy and quick way. Let's have a look!
The video explains in detail how we proceeded to design a benchmark that would provide reliable values ​​both for Arduino and for boards compatible with fast Arm microprocessor onboard.
How do people know there is enough air exchange in their rooms? There is a simple way to make that determined by Seeeduino XIAO.



Write Your Own Review
Only registered users can write reviews. Please Sign in or create an account
  1. Product Quality
    from order view
    A very small PCB that plays well with the expansion board.
  2. Product Quality
    from order view
    Great quality and works as described. The only small issue is the included labels/stickers. The printed text is blurry and somewhat difficult to read.
  3. Product Quality
    from order view
    This micro controller is great for small devices and wearable projects.
  4. Product Quality
    from order view
    I like with Circuitpython, program without IDE
  5. Product Quality
    from order view
    It's an Arduino-compatible SAMD21 board in a small form factor. It's great for when you need a decent bit of processing power (much more than a ATMega328P) but don't need a huge amount of I/O.


Items 1 to 5 of 25 total

Show per page