Getting Started with XIAO STM32C5

Overview

Meet the first STM32-powered XIAO. Built around the STM32C5A3CG with a 144MHz Arm Cortex-M33 core, XIAO STM32C5 brings CAN FD connectivity, 16MB of external Flash, and a six-axis IMU with programmable heating to the compact XIAO form factor. Dedicated heating resistors around the IMU enable firmware-controlled warm-up for robotics and motion-sensing projects. Two native CAN FD controllers, including one channel with an onboard TCAN3403-Q1 transceiver, provide a starting point for USB-to-CAN adapters, connected sensors, and robot control projects. USB-C and onboard battery charging support both desktop development and portable applications.

Features

The First STM32-Powered XIAO: Built with the STM32C5A3CG, featuring a 144MHz Arm Cortex-M33 processor, floating-point support, and DSP instructions for embedded control and sensor processing.
CAN FD Connectivity Built In: Two native CAN FD controllers, with one channel connected to an onboard TCAN3403-Q1 transceiver and accessible CANH/CANL pads. Add an external transceiver to use the second channel.
6-Axis IMU with Programmable Heating: The onboard LSM6DS3TR-C accelerometer and gyroscope are paired with dedicated heating resistors around the sensor. GPIO-controlled heating enables programmable warm-up and, with temperature-feedback firmware, closed-loop temperature regulation to help reduce temperature-related drift in robotics and motion-sensing applications.
16MB External Flash: Store application data, sensor logs, configuration files, and CAN message records using application firmware.
External Crystal for Communication Timing: An onboard high-speed external crystal provides a clock reference for CAN FD and other timing-sensitive applications.
USB-C and Battery Charging: Develop over USB-C or build battery-powered devices using the onboard lithium-battery charging circuit and battery connection pads.
Compact, Integration-Friendly Design: The XIAO form factor and castellated edge pads support breadboard prototyping with headers and integration into custom carrier boards.

Specifications

Item	Specification
Product	Seeed Studio XIAO STM32C5
Microcontroller	STMicroelectronics STM32C5A3CG
CPU	Single-core Arm Cortex-M33, up to 144MHz, with FPU and DSP instructions
MCU package	UFQFPN48
Internal program Flash	1MB
SRAM	256KB
External Flash	16MB
CAN controllers	2 native CAN FD controllers
Onboard CAN transceiver	1 x TI TCAN3403-Q1
Onboard CAN bus connection	CANH/CANL pads; use board GND as the signal reference
Second CAN channel	Digital TX/RX signals; external CAN transceiver required
CAN termination	120 ohms, enabled by default; disconnectable through a cuttable solder link
CAN isolation	No onboard galvanic isolation
IMU	STMicroelectronics LSM6DS3TR-C, three-axis accelerometer and three-axis gyroscope
IMU heating	Dedicated heating resistors around the IMU with GPIO-controlled drive
Temperature regulation	Programmable warm-up; closed-loop setpoint regulation requires temperature feedback and suitable application firmware
External clock	Onboard high-speed external crystal
USB	USB-C; USB 2.0 Full Speed, 12Mbps signaling rate
Logic level	3.3V
Power	USB-C 5V input or compatible lithium battery through BAT pads
Battery charging	Onboard charging circuit
User controls	Reset button and boot button
Indicators	User LED and charging indicator
Debug interface	SWD
Form factor	Compact XIAO module with castellated edge pads

Hardware Overview

XIAO STM32C5

XIAO STM32C5 Front

XIAO STM32C5 Back

Pin Map

XIAO Pin / Signal	Function	Chip Pin	Alternate Functions	Description
VBUS	Power		USB 5V	5V power input/output
GND	Ground			Power ground
3V3 / 3.3V-OUT	Power		VOUT_3V3	Regulated 3.3V output
D0	Analog	PA0	A0, ADC	GPIO and analog input
D1	Analog	PA1	A1, ADC	GPIO and analog input
D2	Analog	PA2	A2, ADC	GPIO and analog input
D3	Analog	PA3	A3, ADC	GPIO and analog input
D4	I2C	PB7	I2C1_SDA	GPIO and I2C data
D5	I2C	PB6	I2C1_SCL	GPIO and I2C clock
D6	UART	PA9	UART_TX	GPIO and UART transmit
D7	UART	PA10	UART_RX	GPIO and UART receive
D8	SPI	PE2	SPI_SCK	GPIO and SPI clock
D9	SPI	PB0	SPI_MISO	GPIO and SPI data input
D10	SPI	PB15	SPI_MOSI	GPIO and SPI data output
D11	CAN FD	PB8	FDCAN1_RX	GPIO and FDCAN1 receive
D12	CAN FD	PB9	FDCAN1_TX	GPIO and FDCAN1 transmit
D13	CAN FD	PB5	FDCAN2_RX	GPIO and onboard CAN transceiver receive
D14	CAN FD	PB13	FDCAN2_TX	GPIO and onboard CAN transceiver transmit
D15	CAN Control	PB14	CAN_STB	Controls onboard CAN transceiver standby mode
CAN_H	CAN Bus		TCAN3403 CANH	CAN FD differential bus high
CAN_L	CAN Bus		TCAN3403 CANL	CAN FD differential bus low
CANFD2_TERM	CAN Termination		JP1, 120 ohm	Cut/open to disable the onboard 120-ohm termination resistor
BAT+	Battery Power		VBAT	Positive terminal for a 3.7V Li-ion/LiPo battery
BAT-	Battery Ground		GND	Negative battery terminal
BAT_EN	Battery Monitor	PA15		Enables the battery-voltage measurement circuit
BAT_READ	Analog	PA4	ADC	Reads battery voltage; ADC input is approximately VBAT / 2
SWCLK	Debug	PA14	SWD Clock	Serial Wire Debug clock pad
SWDIO	Debug	PA13	SWD Data	Serial Wire Debug data pad
RST	System	NRST	STM32C5_RESET	Hardware reset test pad
USB_D+	USB	PA12	USB_DP	USB 2.0 differential data positive
USB_D-	USB	PA11	USB_DN	USB 2.0 differential data negative
BOOT	System	PH2-BOOT0	STM32C5_BOOT	Boot-mode test pad and boot-button signal
CHARGE_LED	Indicator		Charger NCHG output	Red charging-status LED controlled by the charger IC
USER_LED	GPIO Indicator	PB12	GPIO25 / User_LED	Green user LED; connected active-low
IMU_SDA	Onboard IMU	PB4	I2C2_SDA	I2C data for the onboard LSM6DS3TR-C IMU
IMU_SCL	Onboard IMU	PB3	I2C2_SCL	I2C clock for the onboard LSM6DS3TR-C IMU
IMU_INT	Onboard IMU	PC13	IMU_INT1	Interrupt output from the onboard IMU
IMU_HEATER_PWM	IMU Heater	PA8	PWM	PWM control for the IMU temperature-compensation heater

Bootloader Usage

The XIAO STM32C5 is factory‑preloaded with a UF2‑capable bootloader primarily intended for firmware updates. Before flashing a .uf2 file, quickly double‑tap the on‑board Reset button. A mass‑storage drive named XIAOC5BOOT will mount on your PC. You can then copy the firmware file to this drive to complete flashing.

Getting Started With PlatformIO

This section demonstrates development and usage of the XIAO STM32C5 by lighting the on‑board user LED, using the PlatformIO development platform with the Zephyr RTOS framework.

Hardware Preparation

You need to prepare the following:

1 x Seeed Studio XIAO STM32C5
1 x Computer
1 x USB Type-C cable

Seeed Studio XIAO STM32C5

Get One Now 🖱️

Software Preparation

Step 1. Download VS Code

Download according to the system you are using VS Code

Step 2. Install the PlatformIO extension

Open VSCode, click on Extensions, then search for PlatformIO and select to install. After the installation is complete, restart VSCode.

Step 3. Install the platform-seeedboards platform package

The Seeed Studio XIAO series boards use a custom PlatformIO platform, so you need to install the corresponding platform package manually.

Run the following command for a fresh installation:

pio pkg install -g -p "https://github.com/Seeed-Studio/platform-seeedboards.git"

If you have previously used Seeed Studio XIAO series boards in PlatformIO, run the command below to update:

# for Windows
pio pkg update -g -p "https://github.com/Seeed-Studio/platform-seeedboards.git"

# for macOS/Linux
pio pkg uninstall -g -p "SeeedStudio" && pio pkg install -g -p "SeeedStudio=https://github.com/Seeed-Studio/platform-seeedboards.git" --force

tip

If you want to use an existing PlatformIO project, replace the content of platformio.ini as follows:

[env:seeed-xiao-stm32c5]
platform = https://github.com/Seeed-Studio/platform-seeedboards.git
framework = zephyr
board = seeed-xiao-stm32c5

Step 4. Create New Project

On the PlatformIO plugin interface, select to create a new project.

Name your project, choose Seeed Studio XIAO STM32C5 as the target board, and configure the development framework and project storage path.

tip

Project creation may take some time on the first launch, please wait patiently.

Build and Upload

Step 1. Write the LED Blink Program

The XIAO STM32C5 features one user LED mapped to GPIO PB12. The LED turns on at a low logic level; this example configures it to blink every 500 ms.

The project consists of three core files:

main.c: Main program that contains the application logic.
app.overlay: Devicetree overlay file for hardware peripheral configuration.
prj.conf: Project configuration file to enable required Zephyr modules.

Follow the steps below to turn on the LED:

Open your newly‑created project and create the app.overlay devicetree file under the zephyr folder.

/* USB CDC console and the user LED are configured by the board DTS. */

Create the prj.conf configuration file inside the zephyr folder.

# GPIO for LED control
CONFIG_GPIO=y

Copy the reference code shown below into main.c.

/*
 * Copyright (c) 2026 Seeed Technology Co., Ltd.
 * SPDX-License-Identifier: Apache-2.0
 *
 * Blinky example for XIAO STM32C5 with TinyUF2 bootloader support.
 * Based on Zephyr samples/basic/blinky.
 *
 * The 1200-bps UF2 bootloader trigger is armed automatically by the
 * board support package — no code changes needed in this example.
 */

#include <zephyr/kernel.h>
#include <zephyr/drivers/gpio.h>

#define SLEEP_TIME_MS 500

#define LED0_NODE DT_ALIAS(led0)

static const struct gpio_dt_spec led = GPIO_DT_SPEC_GET(LED0_NODE, gpios);

int main(void)
{
	int ret;
	bool led_state = true;

	if (!gpio_is_ready_dt(&led)) {
		return 0;
	}

	ret = gpio_pin_configure_dt(&led, GPIO_OUTPUT_ACTIVE);
	if (ret < 0) {
		return 0;
	}

	while (1) {
		ret = gpio_pin_toggle_dt(&led);
		if (ret < 0) {
			return 0;
		}

		led_state = !led_state;
		printk("LED state: %s\n", led_state ? "ON" : "OFF");
		k_msleep(SLEEP_TIME_MS);
	}

	return 0;
}

Step 2. Build and Upload the Program

On the bottom toolbar, trigger one‑click project building.

Alternatively, you may perform building via the command‑line interface.

pio run -e seeed-xiao-stm32c5

Upload the firmware

Similarly, firmware upload can also be completed through the command line.

pio run -e seeed-xiao-stm32c5 -t upload

Program Execution Result

The on‑board LED of XIAO STM32C5 blinks at a 500 ms interval.

Meanwhile, the serial port outputs the on/off status of the LED.

Battery Usage

A BAT battery connector is reserved on the back side of the XIAO STM32C5 for power supply using a 3.7 V‑4.2 V lithium‑ion battery.

Read Battery Voltage

The XIAO STM32C5 incorporates battery voltage sensing circuitry and battery charging circuitry.

Within the sensing circuit, BAT_EN / PA15 enables the TPS22916CNYFPR chip, while BAT_Reading / PA4 reads the battery voltage. Two 10 kΩ voltage‑divider resistors are used, so the measured value equals one‑half of the actual lithium‑ion battery voltage.

The Charge_LED blinks during battery charging and turns off once charging is complete.

Modify the corresponding application code.

app.overlay

/ {
	/* Expose the battery ADC input to the application. */
	zephyr,user {
		io-channels = <&adc1 4>;
	};
};

&adc1 {
	/* Add the battery input on PA4 (ADC1_IN4). */
	pinctrl-0 = <&adc1_in0_pa0 &adc1_in1_pa1 &adc1_in2_pa2
		     &adc1_in3_pa3 &adc1_in4_pa4>;

	channel@4 {
		reg = <4>;
		zephyr,gain = "ADC_GAIN_1";
		zephyr,reference = "ADC_REF_INTERNAL";
		zephyr,acquisition-time = <ADC_ACQ_TIME(ADC_ACQ_TIME_TICKS, 289)>;
		zephyr,resolution = <12>;
	};
};

prj.conf

# Battery voltage measurement. USB CDC console support is supplied by the board.
CONFIG_ADC=y
CONFIG_GPIO=y

main.c

/*
 * Copyright (c) 2026 Seeed Technology Co., Ltd.
 * SPDX-License-Identifier: Apache-2.0
 *
 * Read the XIAO STM32C5 battery voltage once per second.
 * printk() output uses USB CDC;
 * BAT_Reading/PA4 is added by app.overlay. BAT_EN/PA15 and USB CDC are
 * supplied by the board devicetree.
 */

#include <zephyr/device.h>
#include <zephyr/drivers/adc.h>
#include <zephyr/drivers/gpio.h>
#include <zephyr/kernel.h>
#include <zephyr/sys/printk.h>

#if !DT_NODE_EXISTS(DT_PATH(zephyr_user)) || \
	!DT_NODE_HAS_PROP(DT_PATH(zephyr_user), io_channels)
#error "No battery ADC io-channel specified"
#endif

#define BATTERY_ADC_NODE        DT_PATH(zephyr_user)
#define BAT_EN_NODE             DT_ALIAS(baten)
#define BATTERY_ENABLE_DELAY_MS 5
#define ADC_AVG_SAMPLES         16
#define SAMPLE_PERIOD_MS        1000

static const struct adc_dt_spec battery_adc =
	ADC_DT_SPEC_GET_BY_IDX(BATTERY_ADC_NODE, 0);
static const struct gpio_dt_spec bat_en =
	GPIO_DT_SPEC_GET(BAT_EN_NODE, gpios);

int main(void)
{
	uint16_t raw;
	struct adc_sequence sequence = {
		.buffer = &raw,
		.buffer_size = sizeof(raw),
	};
	int err;

	if (!device_is_ready(battery_adc.dev) || !gpio_is_ready_dt(&bat_en)) {
		printk("Battery ADC hardware is not ready\n");
		return 0;
	}

	err = gpio_pin_configure_dt(&bat_en, GPIO_OUTPUT_ACTIVE);
	if (err) {
		printk("BAT_EN configure failed: %d\n", err);
		return 0;
	}

	k_msleep(BATTERY_ENABLE_DELAY_MS);

	err = adc_channel_setup_dt(&battery_adc);
	if (err) {
		printk("Battery ADC channel setup failed: %d\n", err);
		return 0;
	}

	err = adc_sequence_init_dt(&battery_adc, &sequence);
	if (err) {
		printk("Battery ADC sequence init failed: %d\n", err);
		return 0;
	}

	printk("Battery voltage monitor (USB CDC)\n");

	while (1) {
		uint32_t raw_sum = 0;
		uint16_t raw_avg;
		int32_t adc_mv;

		/* Discard the first conversion after the one-second idle period. */
		err = adc_read(battery_adc.dev, &sequence);
		for (int i = 0; !err && i < ADC_AVG_SAMPLES; i++) {
			err = adc_read(battery_adc.dev, &sequence);
			raw_sum += raw;
		}

		if (!err) {
			raw_avg = raw_sum / ADC_AVG_SAMPLES;
			adc_mv = raw_avg;
			err = adc_raw_to_millivolts_dt(&battery_adc, &adc_mv);
			if (err) {
				printk("Battery voltage conversion failed: %d\n", err);
			} else {
				/* The 1:1 divider halves the battery voltage. */
				printk("Battery: %d mV\n", adc_mv * 2);
			}
		} else {
			printk("Battery ADC read failed: %d\n", err);
		}

		k_msleep(SAMPLE_PERIOD_MS);
	}

	return 0;
}

Voltage Reading Result

IMU

The XIAO STM32C5 carries an on‑board LSM6DS3TR‑C 6‑axis inertial sensor, which integrates a 3‑axis accelerometer and a 3‑axis gyroscope. It can be applied to attitude detection, motion recognition, vibration monitoring and other use‑cases.

To mitigate the impact of ambient temperature variation on sensor bias and measurement stability, the board implements an active temperature‑compensation heating circuit. Heating resistors placed around the IMU provide uniform heating for the sensor, and heating power can be adjusted via PWM signals. Combined with internal temperature readings from the IMU, software control keeps the sensor operating at a relatively stable temperature. This reduces measurement drift caused by temperature drift and improves data consistency during long‑term operation and under variable‑temperature conditions.

Reference Usage: XIAO STM32C5 IMU Usage

CAN FD

The XIAO STM32C5 has two CAN FD controllers. FDCAN1 exposes logic-level TX and RX pins and requires an external CAN transceiver for connection to a CAN bus. FDCAN2 is connected to the onboard TCAN3403-Q1 transceiver and connects to the bus through the CAN_H and CAN_L pads. The board can also exchange Classical CAN frames. However, Classical CAN-only nodes cannot decode CAN FD frames, so confirm that the active nodes on the bus support CAN FD before transmitting FD traffic. CAN FD supports payloads of up to 64 bytes and, when bit-rate switching is enabled, a higher bit rate during the data phase.

The board has a disconnectable onboard 120 Ω termination resistor, enabled by default. Keep it enabled when the XIAO is at a physical end of the CAN bus and that end has no other terminator. Disable it when the XIAO is an intermediate node or another terminator is already installed at the same end. Ensure that the opposite end of the bus is also properly terminated. The transceiver supports standby mode to reduce power consumption when CAN communication is not needed.

Reference Usage: XIAO STM32C5 CANFD Usage

Resources

Hardware Design

📄[Datasheet] STM32C5A3CG
📄[Datasheet] LSM6DS3TR-C
📄[Datasheet] TCAN3403D4BQ1
📄[Schematic] XIAO STM32C5 Schematic
🗃️[PCB Design Files]
- XIAO STM32C5 KiCad Project
- XIAO STM32C5 Eagle Project
🗃️[PCB Design Libraries]
- XIAO Series KiCad Footprints
- XIAO Series KiCad SCH Symbols
📄[Pinout Diagram] XIAO STM32C5 Pinout Sheet

Tech Support & Product Discussion

Thank you for choosing our products! We are here to provide you with different support to ensure that your experience with our products is as smooth as possible. We offer several communication channels to cater to different preferences and needs.

Overview​

Features​

Specifications​

Hardware Overview​

XIAO STM32C5 Front​

XIAO STM32C5 Back​

Pin Map​

Bootloader Usage​

Getting Started With PlatformIO​

Hardware Preparation​

Software Preparation​

Build and Upload​

Battery Usage​

Read Battery Voltage​

IMU​

CAN FD​

Resources​

Tech Support & Product Discussion​