XIAO SAMD21 carries the powerful CPU-ARM® Cortex®-M0+(SAMD21G18) which is a low-power Arduino microcontroller. This little board has good performance in processing but needs less power. As a matter of fact, it is designed in a tiny size and can be used for Arduino wearable devices and small projects.

Apart from the strong CPU, Seeed Studio XIAO SAMD21 is excellent in many other functions. 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 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. Seeed Studio XIAO SAMD21 supports the USB Type-C interface which can supply power and download codes. There are power pads at the back of the Seeed Studio XIAO Series which support battery and make it designed for wearable devices to become realistic. Except for the power LED, we add a user LED on board for a 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.

Highlighted Features

• Powerful CPU: ARM® Cortex®-M0+ 32bit 48MHz microcontroller(SAMD21G18) with 256KB Flash,32KB SRAM
• Flexible compatibility: Compatible with Arduino IDE
• Easy project operation: Breadboard-friendly
• Small size: As small as a thumb(21x17.5mm) for wearable devices and small projects.
• Multiple development interfaces: 11 digital/analog pins, 10 PWM Pins, 1 DAC output, 1 SWD Bonding pad interface, 1 I2C interface, 1 UART interface, and 1 SPI interface.

Applications

• Wearable devices
• Rapid prototyping (directly attached to the expanded PCB as a minimal system)
• Perfect for all the projects that 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 The DAC output

Specifications

• 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
• Support Q-touch function (A0,A1,A6,A7,A8,A9,A10)
• Power supply and downloading 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
• Power Pads: For the battery power supply
• Software compatibility: Compatible with Arduino IDE
• Projection cover for protecting the circuit
• Dimensions: 21x17.5 mm

Hardware Overview

Figure 1: Device Schematics

Figure 2: Similar as above