Seeed Studio XIAO Series consists of five thumb-sized Microcontrollers targeted to different embedded applications. These MCUs offer a variety of I/O peripherals and they are compatible with CircuitPython, Arduino in addition to TinyML.

XIAO SAMD21: This device is based on Microchip’s SAMD21 processor (up to 48MHz) offering 32KB of SRAM and 256KB of onboard flash memory. This tiny board offers 14 GPIO pins in total (11x analog, 11x digital, 1x I2C, 1x UART, 1x SPI, 1x DAC) but no support for wireless connectivity. The XIAO SAMD21 uses a USB Type-C for programming/debugging and supports Arduino only.

XIAO SAMD21 pinout
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XIAO RP2040: Supporting the RP2040 RPi processor (up to 133 MHz) which offers up to 264 KB SRAM and 2MB of onboard flash memory. Unlike the previous product, the RP2040 offers 11x digital pins, 4x analog pins, 11x PWM, 1x I2C, 1x SPI and 1x UART. This MCU is also equipped with 1x Reset button, 1x Boot button, 5x LEDs and a battery pad. The RP2040 can be programmed with Arduino, MicroPython and CircuitPython.

XIAO RP2040 pinout
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XIAO nRF52840/nRF52840 Sense: As its name implies, this MCU accommodates the Nordic nRF52840 System on Chip (SoC) which comes with 256KB RAM, 1MB Flash, 2MB onboard QSPI flash and it supports wireless connectivity (BLE 5.0,NFC, ZigBee). Both models feature similar peripherals, for example, 11x GPIOs, 1x UART, 1x SPI, 1x I2C, 1xNFC and 6x ADC pins. The Sense model includes a 6-axis IMU and a PDM digital microphone.

 
XIAO nRF52840 Sense pinout (left) and layout (right)
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XIAO ESP32C3: Is a RISC-V based board featuring the ESP32-C3 SoC that provides 400SRAM, 4MB flash memory and it has a max frequency of 160MHz. This model is enabled with 2.4GHz Wi-Fi in addition to BLE 5.0 and Bluetooth mesh. The I/O peripherals found in this board include 11x GPIOs(PWM), 4x ADC, 1x UART, 1x I2C, 1x IIS and 1x SPI. Additional features include 1x Power button, 1x Reset button, a battery charging circuit and it supports deep sleep mode (~44 μA).

XIAO ESP32C3 pinout (left) and layout (right)
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See the table below for additional information regarding the features of the XIAO devices. According to the company, shipping is waived if an XIAO device is combined with other accessories if the total order value is below $40. For additional reference, see the XIAO Series product page. 

Comparison table and promo
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