XIAO ESP32C3

Interactive Seeed XIAO ESP32C3 pinout with strapping and BOOT pins marked, battery charging notes, Arduino IDE and PlatformIO setup, and a compile-checked first sketch.

3.3 V logic

Community draft — report a mistake

CPUESP32-C3, single RISC-V core, 160 MHz

Flash / SRAM4 MB / 400 KB

WirelessWi-Fi 4 + Bluetooth 5 LE, external U.FL antenna included

PowerLi-ion/Li-Po charging via BAT pads underneath

Size21 × 17.8 mm, 14 castellated pins

Typical price₹500–800 (indicative)

Seeed’s XIAO ESP32C3 is the smallest board in our list: an ESP32-C3 on a 21 × 18 mm module with castellated edges, so it can be soldered flat onto your own PCB or plugged into a breadboard.

It adds two things the cheap C3 SuperMini lacks — an external U.FL antenna for reliable Wi-Fi range, and a Li-ion charger wired to pads underneath, which makes it a natural choice for battery sensors and wearables.

Pins are labelled D0–D10 to match the other XIAO boards. The pinout below maps each one to its GPIO and marks D0/D8/D9 as strapping pins.

Interactive pinout

Hover or tap a pin for its functions and traps. Filter to light up every I2C, ADC or boot pin.

Safe for most uses
Works, with a caveat
Avoid unless you know why
Power / control

No user LED. The only LED is the charge indicator. The first sketch blinks an external LED on D10 through a 220 Ω resistor.

D0, D8 and D9 are strapping pins. D9 is also the BOOT button. Keep pull-downs and buttons off them at reset.

Fit the antenna before using Wi-Fi. Without the supplied U.FL antenna the range drops to a few metres. Connect it before testing Wi-Fi or Bluetooth.

Set up your computer

Install Arduino IDE 2.x from arduino.cc.
File → Preferences → Additional boards manager URLs: https://espressif.github.io/arduino-esp32/package_esp32_index.json
Boards Manager → install esp32 by Espressif Systems (we compile against esp32 3.3.12).
Tools → Board → XIAO_ESP32C3, then pick the port that appears when you plug the board in.

Your platformio.ini:

platformio.iniOutput

[env:seeed_xiao_esp32c3]
platform = espressif32
board = seeed_xiao_esp32c3
framework = arduino
monitor_speed = 115200

[env:seeed_xiao_esp32c3]
platform = espressif32
board = seeed_xiao_esp32c3
framework = arduino
monitor_speed = 115200

Download the firmware from micropython.org.
Hold BOOT while plugging in USB, flash with esptool, then open Thonny → Interpreter → MicroPython (ESP32).

First program

Verified — core esp32 3.3.12, 3 Nov 2026Compile-only

blink-xiao-c3.inoArduino C++Open in Playground Flash

// First program for the Seeed XIAO ESP32C3. The board has no user LED, so wire one:
//   D10 → 220 Ω resistor → LED anode, LED cathode → GND.
// Serial runs over the native USB port at 115200 baud.
constexpr uint8_t LED_PIN = D10;

void setup() {
  Serial.begin(115200);
  pinMode(LED_PIN, OUTPUT);
  Serial.println("FlashReady: XIAO ESP32C3 blink");
}

void loop() {
  digitalWrite(LED_PIN, HIGH);
  delay(500);
  digitalWrite(LED_PIN, LOW);
  delay(500);
}

// First program for the Seeed XIAO ESP32C3. The board has no user LED, so wire one:
//   D10 → 220 Ω resistor → LED anode, LED cathode → GND.
// Serial runs over the native USB port at 115200 baud.
constexpr uint8_t LED_PIN = D10;

void setup() {
  Serial.begin(115200);
  pinMode(LED_PIN, OUTPUT);
  Serial.println("FlashReady: XIAO ESP32C3 blink");
}

void loop() {
  digitalWrite(LED_PIN, HIGH);
  delay(500);
  digitalWrite(LED_PIN, LOW);
  delay(500);
}

Components with XIAO ESP32C3

Common errors

Board not detected after a bad sketch

Hold BOOT while plugging in USB to force download mode, then upload a working sketch.

Battery does not charge

Charging only works with USB connected and a single-cell 3.7 V Li-ion/Li-Po on the BAT pads with the right polarity. A full battery leaves the charge LED off.

Serial Monitor prints nothing

Add a short delay (or while (!Serial) with a timeout) after Serial.begin() — native USB takes a moment to enumerate.

Projects for XIAO ESP32C3

Grain storage humidity logger with phone alerts (XIAO ESP32C3 + SHT40, battery)

XIAO C3Easy

Know when the rice or wheat drum is getting damp — months on one Li-ion cell.

1.5 h · India utility

₹1,330Verified core 3.3

Radar alarm for a cattle shed or godown with a 433 MHz HC-12 link (XIAO ESP32C3)

XIAO C3Medium

Movement in the shed at night? The buzzer by your bed knows — no Wi-Fi or SIM needed.

3 h · India utility

₹2,495Verified core 3.3

Temperature-controlled cooling fan for a router or ONT cabinet (XIAO ESP32C3)

XIAO C3Easy

Keeps the router cabinet cool in May — quiet when it’s cool, full speed when it’s hot.

1.5 h · Network & ISP tools

₹1,510Verified core 3.3