Seeed Studio XIAO ESP32C3 Pinout

Seeed Studio XIAO ESP32C3 is a thumb-sized board (21 × 17.8 mm) with the ESP32-C3 chip. Compared to the SuperMini, it has a Li-Po cell charger, a connector for an external antenna and better build quality.

The pin layout is the same across the entire XIAO series, so expansion boards fit the other models as well.

Specifications

ESP32-C3: RISC-V up to 160 MHz, 400 kB SRAM, 4 MB flash
Wi-Fi 4 (2.4 GHz) and Bluetooth 5 (LE), external antenna (U.FL)
11 GPIO on the headers (D0–D10), 4 of them analog inputs
UART, I2C, SPI and PWM
USB-C (native USB), Li-Po cell charging via the BAT pads on the bottom
21 × 17.8 mm, castellated pads on the edge

The XIAO form factor is shared by the XIAO ESP32S3, ESP32C6, RP2040 and nRF52840 – the Grove shield and XIAO displays fit all of them.

Pinout and pin table

Hover over a pin in the diagram or a table row; use the filter to highlight a bus. You can download the pinout as PNG or SVG.

Pin names:

Bottom side

Download:PNG SVG

Download – Bottom side:PNG SVG

License: CC BY 4.0 · How to credit

Pin table – Seeed Studio XIAO ESP32C3
Pin	Name	Arduino	Direction	UART	I2C	SPI	ADC	Note
1	GPIO2	D0/A0	input/output				ADC1_CH2	Strapping pin – should be logic 1 at boot (pull-up recommended)
2	GPIO3	D1/A1	input/output				ADC1_CH3
3	GPIO4	D2/A2	input/output				ADC1_CH4	JTAG MTMS
4	GPIO5	D3	input/output				ADC2_CH0	ADC2 is not calibrated and does not work on some chip revisions – prefer ADC1. JTAG MTDI
5	GPIO6	D4	input/output		SDA			JTAG MTCK
6	GPIO7	D5	input/output		SCL			JTAG MTDO
7	GPIO21	D6	input/output	TX				UART0 TX
8	GPIO20	D7	input/output	RX		SS		UART0 RX; also the default SS for SPI in Arduino
9	GPIO8	D8	input/output			SCK		Strapping pin – must be logic 1 at boot for download mode
10	GPIO9	D9	input/output			MISO		Button B (BOOT). Strapping pin – logic 0 at boot = download mode
11	GPIO10	D10	input/output			MOSI
12	3V3		output					3.3 V output from the regulator
13	GND		–
14	5V		input/output					5 V from the USB connector. It can also power the board – ideally connect the supply through a diode so voltage does not flow back into USB.
Bottom side	EN		input					Reset – connecting to GND restarts the chip
Bottom side	GND		–
Bottom side	BAT+		input/output					3.7 V Li-Po cell positive – the board charges it from USB
Bottom side	BAT-		–					Cell negative (GND)

Pins used on the board

These chip pins are used by parts on the board and are not broken out:

Pin	Function on the board
GPIO18	USB D−
GPIO19	USB D+

What to watch out for

The GPIO are not 5V tolerant. Use a level shifter for 5V signals.
Wi-Fi barely works without the antenna connected – the antenna is included in the package.
Strapping pins: D9 (GPIO9) is the BOOT button, D8 (GPIO8) must be at logic 1 at boot for uploading, D0 (GPIO2) should be at logic 1 at boot.
The analog input on D3 (GPIO5) is on ADC2 – it is not calibrated and does not work on some chip revisions. The Arduino core for XIAO ESP32C3 has no A3 constant, use D3.
The board has no user LED, only the charging LED.
Only connect a 3.7 V Li-Po/Li-Ion cell to the BAT pads.

Related projects on chiptron.eu/

On chiptron.eu/ you will find these related projects and tutorials:

MeshCore – off-grid LoRa communication, also supports Seeed XIAO C3 and S3 boards
ESP-Scope – pocket web oscilloscope on the tiny XIAO ESP32C6 board
ESP32 Plane Radar – aircraft radar on an ESP32-C3 Super Mini with a round GC9A01 display
ESP32 chip comparison – which ESP32 to choose based on peripherals and project needs