Seeed Studio XIAO ESP32C3 Pinout

The XIAO ESP32C3 is Seeed Studio’s smallest ESP32-C3 board: 21×17.8mm, USB-C, and an external U.FL antenna connector instead of a printed one. It trades a smaller footprint and fewer exposed pins for size, aimed at wearables and battery projects rather than breadboard prototyping. Pin data below is sourced from Seeed’s own wiki.

System-on-chip

The ESP32-C3 is a single-core, 160MHz RISC-V chip with Wi-Fi 802.11 b/g/n and Bluetooth 5 (LE), the same chip family covered on this site’s ESP32-C3-MINI-1 page. The XIAO board exposes only 11 of the chip’s GPIOs, in exchange for its very small size.

GPIO reference

No onboard LED. Unlike most ESP32 devkits, the XIAO ESP32C3 has no built-in status LED, wire an external one to test blink code. Power (5V USB VBUS, regulated 3V3 output, GND) is broken out on separate header pins.

Real gotchas

• Strapping pins (GPIO2, GPIO8, GPIO9) set the chip’s boot mode at power-on. Avoid wiring anything to these that could pull them the wrong way at reset, per Seeed’s own documentation.
• D3/GPIO5 is ADC2, which shares internal resources with the Wi-Fi radio, readings can become unreliable once Wi-Fi is connected. Use D0–D2 (ADC1) for reliable analog input instead.
• External antenna required. This board has a U.FL connector, not a printed PCB antenna, an external 2.4GHz antenna (commonly included with the board) must be attached for Wi-Fi/BLE to work at all.

Conclusion

The XIAO ESP32C3 fits where the AI-C3 or bare ESP32-C3-MINI-1 module is too big, at the cost of fewer breakout pins and no onboard LED. Need more GPIOs and native USB in a similarly small board? See the XIAO ESP32S3.

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