XIAO Arduino Development

Overview

Complete Arduino development guide for SeeedStudio XIAO series. This skill works with the /xiao skill - use /xiao for pin definitions, /xiao-arduino for platform-specific APIs and libraries.

Arduino Project Structure (CRITICAL)

Arduino requires a specific folder/file structure:

1. •

   Folder name must match the .ino filename

   • •Example: If your sketch is named Blink.ino, it must be in a folder named Blink
   • •The .ino file is the main file - Arduino IDE automatically generates other files
2. •

   One .ino file per folder

   • •Each Arduino project (sketch) has its own folder
   • •The folder name = the .ino filename (without extension)

MyArduinoProjects/
├── BlinkRPM/
│   └── BlinkRPM.ino          # Folder = filename
├── CanBusOBDII/
│   └── CanBusOBDII.ino       # Folder = filename
└── WeatherStation/
    └── WeatherStation.ino    # Folder = filename

Code Generation Workflow (CRITICAL)

When a user requests Arduino code generation, you MUST:

Step 1: Create Project Files

• •Use the Write tool to create the actual .ino file in the appropriate directory
• •Create the folder structure matching the Arduino requirements
• •Example: Create XIAO_Expansion_Base_RTC/XIAO_Expansion_Base_RTC.ino

Step 2: Verify Compilation (If arduino-cli is Available)

• •After creating the file, run arduino-cli compile to verify the code compiles
• •Use the appropriate FQBN for the target board
• •Report compilation results to the user

Prerequisites

1. •Pin Definitions: Read /xiao skill first for board-specific pin mappings
2. •Arduino IDE or CLI: Version 2.x/1.8.x IDE, or Arduino CLI
3. •Board Package: Install via Board Manager or Arduino CLI

Environment Setup

For first-time Arduino environment installation, see setup/:

• •Arduino IDE Installation: setup/arduino-ide.md
• •Arduino CLI Installation: setup/arduino-cli.md (for CI/CD and automation)
• •USB Drivers: setup/drivers.md
• •Troubleshooting: setup/troubleshooting.md

Quick Start by Board

Board-Specific APIs

Each chipset has unique Arduino APIs beyond standard Arduino functions:

ESP32 Series (C3/C5/C6/S3)

• •WiFi: See api/esp32-wifi.md
• •BLE: See api/esp32-ble.md
• •Hardware: Timer, PWM, ADC in api/esp32-hw.md
• •Deep Sleep: api/esp32-sleep.md

nRF52 Series (nRF52840, MG24)

• •BLE: See api/nrf-ble.md
• •Deep Sleep: api/nrf-sleep.md

Sense Boards (ESP32S3 Sense, nRF52840 Sense, MG24 Sense)

Onboard Peripherals - Sense versions include built-in sensors:

• •Camera (ESP32S3 Sense only): api/camera.md
• •IMU Sensor (6-axis accelerometer+gyroscope): api/imu-sensor.md
• •Microphone (PDM/Analog audio): api/microphone.md
• •NFC (nRF52840 only): api/nfc.md

Board Reference - For Sense-specific pin mappings:

• •ESP32S3 Sense: See xiao/references/boards/esp32s3.md (camera, mic, SD card)
• •nRF52840 Sense: See xiao/references/boards/nrf52840.md (IMU, mic, NFC)
• •MG24 Sense: See xiao/references/boards/mg24.md (IMU, mic)

RP Series (RP2040, RP2350)

• •PIO: See api/rp2040-pio.md
• •Deep Sleep: api/rp-sleep.md

SAMD Series (SAMD21, RA4M1)

• •USB: See api/samd-usb.md
• •ADC/DAC: See api/samd-adc.md

Common Arduino Libraries

Communication

Networking (ESP32)

Actuators

Storage

Sensors

Displays

Expansion Boards

XIAO expansion boards add peripherals and capabilities. For hardware specifications and pin connections, see /xiao/references/expansion_boards/.

Note: Hardware documentation is in /xiao/references/expansion_boards/. Arduino code examples are in expansion-boards/ and expansion-boards/examples/.

Code Patterns

Basic Structure

// Includes
#include <Arduino.h>
#include <Wire.h>

// Pin definitions (from /xiao skill)
#define LED_PIN D10
#define SENSOR_PIN A0

// Setup
void setup() {
    Serial.begin(115200);
    pinMode(LED_PIN, OUTPUT);
}

// Loop
void loop() {
    digitalWrite(LED_PIN, HIGH);
    delay(1000);
    digitalWrite(LED_PIN, LOW);
    delay(1000);
}

Non-blocking Delay

unsigned long lastUpdate = 0;
const unsigned long interval = 1000;

void loop() {
    if (millis() - lastUpdate >= interval) {
        lastUpdate = millis();
        // Do something
    }
}

Code Verification

After generating Arduino code, verify it compiles correctly.

Quick Verification (If Arduino CLI is Already Set Up)

# If sketch file already exists, just compile:
arduino-cli compile --fqbn <FQBN> <sketch_dir>

# Example for XIAO ESP32C3:
arduino-cli compile --fqbn esp32:esp32:esp32c3 MySketch

Full Verification (First-Time Setup)

Step 1: Create Sketch File (if not exists)

# Create sketch directory
mkdir MySketch
cd MySketch

# Create main .ino file (must match directory name)
cat > MySketch.ino <<'EOF'
// Your generated code here
EOF

Step 2: Install Required Libraries (if not already installed)

# Check if library is installed
arduino-cli lib list

# Install missing libraries
arduino-cli lib install WiFi
arduino-cli lib install Wire
arduino-cli lib install Adafruit_BME280

Step 3: Compile with Arduino CLI

# Determine FQBN for target board:
# ESP32C3: esp32:esp32:XIAO_ESP32C3
# ESP32C5: esp32:esp32:XIAO_ESP32C5
# ESP32C6: esp32:esp32:XIAO_ESP32C6
# ESP32S3: esp32:esp32:XIAO_ESP32S3
# nRF52840: Seeeduino:nrf52:xiaonRF52840
# nRF52840 Sense: Seeeduino:nrf52:xiaonRF52840Sense
# RP2040: rp2040:rp2040:seeed_xiao_rp2040
# RP2350: rp2040:rp2040:seeed_xiao_rp2350
# SAMD21: Seeeduino:samd:seeed_XIAO_m0
# MG24: SiliconLabs:silabs:xiao_mg24
# RA4M1: Seeeduino:renesas_uno:XIAO_RA4M1

# Compile sketch
arduino-cli compile --fqbn <FQBN> MySketch

Step 4: Verify Compilation Output

✅ Successful compilation:

Sketch uses 123456 bytes (0%) of program storage space.
Global variables use 12345 bytes (0%) of dynamic memory.

Common Errors and Solutions

Verification Checklist

After generating code, verify:

• • All required libraries have #include directives
• • Pin definitions match the XIAO board (use /xiao skill)
• • FQBN matches the target hardware
• • Code compiles without errors
• • Memory usage is within board limits

Example: Complete Verification

// Blink.ino - Generated for XIAO ESP32C3

#include <Arduino.h>

#define LED_PIN D10  // Built-in LED (from /xiao skill)

void setup() {
    pinMode(LED_PIN, OUTPUT);
    Serial.begin(115200);
}

void loop() {
    digitalWrite(LED_PIN, HIGH);
    delay(1000);
    digitalWrite(LED_PIN, LOW);
    delay(1000);
}

Verification command:

arduino-cli compile --fqbn esp32:esp32:esp32c3 Blink

Platform Configuration

Arduino IDE 2.x: Tools > Board Options

nRF52 Board Manager Settings

Troubleshooting

Upload Fails

1. •ESP32: Hold BOOT button, click Upload, release when "Connecting..."
2. •nRF52: Double-click RESET button, enters bootloader
3. •RP2040: Hold BOOTSEL while connecting USB

Port Not Found

1. •Check USB cable (data + power, not power-only)
2. •Install drivers:
   • •ESP32: CH340/CP2102
   • •nRF52: Adafruit nRF52 driver
   • •RP2040: No driver needed
3. •Try different USB port

Compilation Errors

1. •Update board package
2. •Update libraries
3. •Check selected board matches hardware

Resources

setup/

Environment installation and configuration:

• •setup/arduino-ide.md - Arduino IDE installation (Windows/macOS/Linux)
• •setup/arduino-cli.md - Arduino CLI installation and usage (for CI/CD)
• •setup/drivers.md - USB driver requirements per board
• •setup/troubleshooting.md - Common Arduino IDE issues and solutions

getting-started/

Board-specific setup instructions and first steps.

api/

Chipset-specific Arduino APIs (WiFi, BLE, PIO, etc.)

libraries/

Common Arduino libraries with XIAO-specific notes.

examples/

Complete project examples demonstrating best practices.

expansion-boards/

Arduino implementation for XIAO expansion boards:

• •expansion-boards/expansion-base.md - Arduino code for Expansion Base (OLED, RTC, SD, buzzer)
• •expansion-boards/round-display.md - Arduino code for Round Display touchscreen
• •expansion-boards/grove-shield.md - Arduino code for Grove Shield
• •expansion-boards/epaper-v2.md - Arduino code for ePaper V2 displays
• •expansion-boards/can-bus.md - Arduino code for CAN Bus communication
• •expansion-boards/rs485.md - Arduino code for RS485 communication
• •expansion-boards/led-driver.md - Arduino code for LED Driver board
• •expansion-boards/bus-servo.md - Arduino code for Bus Servo control
• •expansion-boards/gps-gnss.md - Arduino code for GPS/GNSS positioning
• •expansion-boards/gpio-expander.md - Arduino code for MCP23017 GPIO expander
• •expansion-boards/rgb-matrix.md - Arduino code for RGB LED matrix
• •expansion-boards/cob-led.md - Arduino code for COB LED lighting

For hardware specifications, see /xiao/references/expansion_boards/.

Related Skills

• •/xiao - Core board reference with pin definitions
• •/xiao-micropython - MicroPython development
• •/xiao-esphome - ESPHome configuration