BoardSeeed Studio

Seeed Studio XIAO ESP32C3

Seeed Studio XIAO ESP32C3: a 21 x 17.8 mm third-party board for the ESP32-C3 with 14 edge pads in two columns (left D0-D6, right 5V/GND/3V3/D10-D7), back-side BAT and JTAG pads, the bundled external U.FL antenna, Li-ion charging, and Reset/Boot buttons. A Seeed board, not an Espressif DevKit.

Specifications

Specifications
Flash	4 MB

Assembly & compatibility

Main chip: ESP32-C3

Revisions

Current production board — Seeed publishes one current board without a PCB revision number; 'v1' is an internal ordering id, not an official revision label. · Seeed Studio XIAO ESP32C3 wiki (getting started, pin map, pin multiplexing) · sites/en/docs/Sensor/SeeedStudio_XIAO/SeeedStudio_XIAO_ESP32C3/XIAO_ESP32C3_Getting_Started.md#L34-L80

Pinout

power · ground · GPIO / signal · onboard LED

Edge pads, two columns (front, USB up: left D0-D6, right 5V/GND/3V3/D10-D7) (14 pins)

Physical order from the official front pinout image (USB up): left column top-to-down D0..D6, right column top-to-down 5V/GND/3V3/D10/D9/D8/D7. GPIO map transcribed from the wiki getting-started pin table. Back-side battery and JTAG pads are separate connectors (BAT/DEBUG), not edge pads. · Source: Seeed Studio XIAO ESP32C3 wiki (getting started, pin map, pin multiplexing) · sites/en/docs/Sensor/SeeedStudio_XIAO/SeeedStudio_XIAO_ESP32C3/XIAO_ESP32C3_Getting_Started.md#L109-L131

No.	Name	Type	GPIO	Function
1	D0	I/O	2	GPIO2; ADC1_CH2; analog input
2	D1	I/O	3	GPIO3; ADC1_CH3; analog input
3	D2	I/O	4	GPIO4; ADC1_CH4; FSPIHD; MTMS (JTAG)
4	D3	I/O	5	GPIO5; ADC2_CH0; FSPIWP; MTDI (JTAG)
5	D4	I/O	6	GPIO6; FSPICLK; MTCK; default I2C data on the silk
6	D5	I/O	7	GPIO7; FSPID; MTDO; default I2C clock on the silk
7	D6	I/O	21	GPIO21; U0TXD; UART transmit (bootloader log output; prefer output-only use)
8	5V	P		VBUS power input/output
9	GND	G		Ground
10	3V3	P		3.3 V regulated output; max 500 mA (spec condition: BAT pin input @ 3.8 V, source capability 3 A)
11	D10	I/O	10	GPIO10; FSPICS0; SPI data out
12	D9	I/O	9	GPIO9; SPI data in; BOOT button + pull-up R6 - best used as switch input
13	D8	I/O	8	GPIO8; SPI clock; strapping pin - must be HIGH for download boot
14	D7	I/O	20	GPIO20; U0RXD; UART receive

Back-side battery pads (BAT+ / BAT-) (2 pins)

From the official back pinout image; battery pads are on the board back, grouped separately from the 14 edge pads. · Source: Seeed Studio XIAO ESP32C3 wiki (getting started, pin map, pin multiplexing) · sites/en/docs/Sensor/SeeedStudio_XIAO/SeeedStudio_XIAO_ESP32C3/XIAO_ESP32C3_Getting_Started.md#L109-L131

No.	Name	Type	GPIO	Function
1	BAT+	P		Li-ion battery positive (3.7 V cell; charging 380 mA fast / 40 mA trickle)
2	BAT-	G		Li-ion battery negative

Back-side JTAG/test pads, two columns (MTDO/GND/MTCK and MTDI/EN/MTMS) (6 pins)

From the official back pinout image + wiki pin table (JTAG rows). Each column top-to-down as printed. GPIO numbers per the wiki table; EN is CHIP_EN, no GPIO number. · Source: Seeed Studio XIAO ESP32C3 wiki (getting started, pin map, pin multiplexing) · sites/en/docs/Sensor/SeeedStudio_XIAO/SeeedStudio_XIAO_ESP32C3/XIAO_ESP32C3_Getting_Started.md#L109-L131

No.	Name	Type	GPIO	Function
1	MTDO	I/O	7	GPIO7; JTAG TDO (same GPIO as D5)
2	GND	G		Ground
3	MTCK	I/O	6	GPIO6; JTAG TCK (same GPIO as D4)
4	MTDI	I/O	5	GPIO5; JTAG TDI (same GPIO as D3)
5	EN	I		CHIP_EN (reset)
6	MTMS	I/O	4	GPIO4; JTAG TMS (same GPIO as D2)

The Seeed Studio XIAO ESP32C3 packs an ESP32-C3 onto a 21 x 17.8 mm board: 14 edge pads in two columns — front-left, USB up, D0-D6 top-to-down; front-right 5V/GND/3V3/D10/D9/D8/D7 — plus back-side BAT+ / BAT- battery pads and JTAG/test pads (MTDO/GND/MTCK and MTDI/EN/MTMS), a Reset and a Boot button, and a U.FL connector for the bundled external antenna (there is no antenna on the board itself; the wiki overview says one is included). This page renders the MCUID data record: the full pin map with GPIO numbers, the three pads that need care (D9/D6/D8), and every published field tied to a fixed official source.

Two facts set this board apart on this site:

It is a third-party carrier, not an Espressif DevKit. The chip is Espressif's ESP32-C3, but the board, the pin naming and the docs are Seeed's. Searching for "C3 DevKitM" answers will give you wrong pin numbers here.
Three pads carry official usage notes. D9 shares the BOOT button (best as a switch input), D6 is the bootloader's UART log output (output-only recommended), D8 is the GPIO8 strapping pin (needs pull-up for download boot). The head-to-head with the LOLIN C3 mini is C3 mini vs XIAO ESP32C3.

Start developing

Bring-up — Seeed's official getting-started wiki (pin map, antenna, battery) and the pin-multiplexing guide (PWM/UART/I2C/SPI examples plus the D9/D6/D8 allocation notes).
You need an antenna connected. The board ships with a bundled external U.FL antenna per the wiki overview, and the radio needs it connected (or a compatible U.FL antenna) — there is no on-board antenna.
Default I2C scope — D4/D5 carry the SDA/SCL silk names (GPIO6/GPIO7); which pins the Arduino Wire() object uses is framework behavior, outside what Seeed's wiki asserts.

Power and battery

5V (VBUS) or the BAT pads (3.7 V Li-ion, 380 mA fast / 40 mA trickle charging); the 3V3 pad is a regulated output with a conditional 500 mA max (spec table: BAT pin input @ 3.8 V, source capability 3 A; the same wiki Power Pins section says "you can draw 700 mA" — recorded as a conflict, the conditional 500 mA figure is used). The "Light" pad is the charge-status LED, not a user LED — the ESP32-C3 has no on-board LED on this design.

Compared with the ESP32-C3-DevKitM-1

Coming from the ESP32-C3-DevKitM-1? Same chip, opposite philosophy: the DevKit is Espressif's evaluation board with two full headers, a USB bridge and strapping pins on numbered J1/J3 positions; the XIAO is Seeed's thumb-size module with 14 two-column pads, castellated edges and an external antenna. Pin maps do not transfer — check the pin table above, not DevKit documentation.