Key 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(20x17.5mm) 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, 1 SPI interface. Specification 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 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 Dimensions: 20x17.5x3.5 mm 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 The DAC output Sources : https://files.seeedstudio.com/wiki/Seeeduino-XIAO/res/Seeeduino-XIAO-HDK.pdf