Seeed Studio XIAO ESP32C3 pinout
ESP32-C3 board. Pick XIAO_ESP32C3 in the Arduino IDE. 6 of its header GPIOs are free of boot, flash and USB duties.
XIAO C3
D720
21D6
D88
7D5
D99
6D4
D1010
5D3
3V3
4D2
GND
3D1
5V
2D0
Field notes
- Pad names on the silkscreen are D0 to D10. This page shows the GPIO number next to each, and sketches use the GPIO number.
- D0 (GPIO 2), D8 (GPIO 8) and D9 (GPIO 9) are strapping pins. GPIO 9 is also the BOOT button.
- Serial output goes over the USB-C port. D6 and D7 are UART0 TX and RX.
- Default I2C is D4 (GPIO 6) for SDA and D5 (GPIO 7) for SCL.
- The antenna is a separate U.FL whip. Wi-Fi range is poor with nothing attached.
Analog and Wi-Fi
ADC2 (GPIO 5) gives unstable readings because of a chip erratum, and ESP-IDF no longer supports it in oneshot mode. Use GPIO 0 to 4 for analog.
Every pin
Pads in order from the top, with the USB connector at the bottom. Numbers are GPIO numbers, which is what sketches use.
| Pad | Label | GPIO | Can do | Use it? |
|---|---|---|---|---|
| Left 1 | D7 | 20 | UART0 RX | Serial UART0 RX. |
| Left 2 | D8 | 8 | — | Boot pin A strapping pin. It must be high to enter download mode. |
| Left 3 | D9 | 9 | — | Boot pin A strapping pin and the BOOT button. |
| Left 4 | D10 | 10 | — | Safe A general-purpose pin with no boot, flash or USB duty. |
| Left 5 | 3V3 | — | — | Power The 3.3 V output. |
| Left 6 | GND | — | — | Power Ground. |
| Left 7 | 5V | — | — | Power The 5 V supply from USB. |
| Right 1 | D6 | 21 | UART0 TX | Serial UART0 TX. The ROM boot messages come out here. |
| Right 2 | D5 | 7 | JTAG MTDO | Safe A general-purpose pin with no boot, flash or USB duty. |
| Right 3 | D4 | 6 | JTAG MTCK | Safe A general-purpose pin with no boot, flash or USB duty. |
| Right 4 | D3 | 5 | ADC2_CH0, JTAG MTDI, Deep-sleep wake | Safe A general-purpose pin with no boot, flash or USB duty. |
| Right 5 | D2 | 4 | ADC1_CH4, JTAG MTMS, Deep-sleep wake | Safe A general-purpose pin with no boot, flash or USB duty. |
| Right 6 | D1 | 3 | ADC1_CH3, Deep-sleep wake | Safe A general-purpose pin with no boot, flash or USB duty. |
| Right 7 | D0 | 2 | ADC1_CH2, Deep-sleep wake | Boot pin A strapping pin. It must be high at reset. |
The ESP32-C3 chip
| Feature | Value |
|---|---|
| CPU | Single-core RISC-V, up to 160 MHz |
| Radio | Wi-Fi 4 (2.4 GHz) and Bluetooth LE 5 |
| GPIOs | 22 |
| Analog in | 6 channels: ADC1 on GPIO 0 to 4, ADC2 on GPIO 5 |
| Touch | None |
| Analog out | None |
| USB | USB serial/JTAG port on GPIO 18 and 19 |
| SRAM | 400 KB |
Projects for this board
- Wi-Fi scanner List nearby networks with signal strength and channel every ten seconds. A quick radio health check.
- I2C bus scanner Probe every address on the I2C bus and report what answers. Run it before trusting any sensor wiring.
- ESP-NOW pair Two boards talk directly over the Wi-Fi radio, with no router. Each sends a counter and prints what the other sends.
- Bluetooth LE scanner List nearby Bluetooth LE devices with their signal strength every ten seconds: phones, watches, beacons and sensors.