The Seeeduino Xiao boasts an impressively compact size, low price tag, and formidable hardware. It is hard not to be a fan of Seeed after having used the Xiao. As a board retailer and manufacturer, Seeed Studio regularly pushes out powerful products that are insanely inexpensive compared to their competitors; we see this with their Seeeduino line. The Xiao is the smallest member of the Seeeduino family. With a dimension of 20×17.5mm, this cutie is a fraction of the Arduino Nano’s size. As the name implies, it is fully Arduino-compatible, but can also run PlatformIO and Adafruit’s CircuitPython.

Speaking of Adafruit, it is hard to have an article about the Seeeduino Xiao without comparing it to the new Adafruit QT Py. Their use case may seem interchangeable at first glance, but the differences are big enough to have a non-trivial effect on the project in which they are used.

Like the QT Py, the Xiao contains the low-powered 32-bit ARM Cortex M0+. It also has 11 GPIO pins, an I2C, UART, and SPI interface configuration, and two built-in LEDs. A notable physical characteristic of this board is its lack of a reset button; instead, Seeed Studio chose to have two RST contact pads that you will have to short to reset your board.

Since its initial release, Seeed has developed expansion boards to upgrade the Xiao’s capabilities. The Seeeduino Xiao expansion board includes an onboard OLED display, servo connectors, the fabled reset button, expandable memory, a real-time clock, an SWD pin, Lipo battery management system and port, Grove connectors, and a passive buzzer. Not a bad deal for an extra $15. As you’d expect, the expansion board increases the overall size of the Xiao, but it’s about half the size of a Raspberry Pi 4.

Setting up the Seeeduino Xiao development environment was amazingly effortless. For one, the documentation I followed just worked. I was up and running in the Arduino IDE in minutes using their getting started guide. CircuitPython was also straightforward to install and run on the Xiao following this tutorial. The wiki for the Seeeduino Xiao has a plethora of other resources to get you familiar with the microcontroller, such as pin layouts and community project tutorials.

While the QT Py has similar specs with extra bells and whistles, the Xiao initially is still the more economical board. The Adafruit QT Py initially sold for $6 a pop as a limited time offer, but as of this review is currently out of stock. While it is unknown what the new price will be for the QT Py, I expect a reasonable price increase based on its additional features. The Seeduino Xiao meanwhile costs $4.90 solderless and $5.90 pre-soldered. That’s pretty dang cheap for a microcontroller! Fancy coffee in cities are more expensive than this board.

The Xiao is a fun, bite-sized development board that runs as smooth as the standard Arduino board. Choosing between the Xiao and the QT Py comes down to what works best for your build. If you find yourself using a lot of Adafruit sensors, the STEMMA Qt connector on the QT Py is pretty fantastic for a plug-and-play experience. If you want a tiny microcontroller that’s dirt cheap with most of the same specs, I’d say give the Seeeduino Xiao a look.

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

– Interface: 1 I2C interface,1 UART interface, 1 SPI interface
– Power supply and downloading interface: USB Type-C interface
– LEDs: 1 user LED, 1 power LED, two LEDs for serial port downloading
– Reset button: two reset button short connect to reset
– Power Pads: For the battery power supply
– Software compatibility: Compatible with Arduino IDE
– Projection cover for protecting the circuit