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Seeed XIAO boards

Thumb-sized microcontroller boards (RP2040, ESP32-C6, nRF52840) with USB-C, 11 GPIOs and a 3.3 V output, soldered onto your board as a module.

What it does#

A XIAO is a complete microcontroller board, 21 × 17.5 mm, with USB-C, regulator and reset/boot buttons. You solder it onto your PCB by its castellated edges (or on headers) and connect your parts to its 14 pins: D0–D10, 5V, GND, 3V3. All boards in the family share the pinout, so the same footprint takes an RP2040, an ESP32-C6 (Wi-Fi) or an nRF52840 (Bluetooth, with battery pads underneath).

Example circuit: An LED with its resistor on D0 and a button to GND on D1 (use the internal pull-up). C1 decouples whatever you hang on the 3V3 pin.
An LED with its resistor on D0 and a button to GND on D1 (use the internal pull-up). C1 decouples whatever you hang on the 3V3 pin. Open the xiao_led_button example from this page in PCB Canvas: “Insert into my schematic”.

Power#

  • 5V is USB VBUS when plugged in. You can feed 5 V in here instead of USB, but not both at once without a diode.
  • 3V3 is the board’s regulator output; a few hundred mA are available for sensors and LEDs.
  • GPIOs are 3.3 V. Never put 5 V on them.

Pitfalls#

  • Castellated soldering: align it, tack two corners, then flow solder into each half-hole. Pads under the nRF52840 variant (BAT+/BAT−) need hot air or holes in your PCB.
  • USB-C overhang: put the module at the board edge so a cable fits.
  • The macropad example uses a XIAO RP2040; see the in-app tutorial.

Footprint#

Through-hole/castellated XIAO footprint in PCBCanvas_Modules. Hand-soldered (JLCPCB does not place it).