xiao-arduino

name	xiao-arduino
description	Complete Arduino development for XIAO boards. Use when writing Arduino sketches for XIAO (ESP32C3/C5/C6/S3, nRF52840, RP2040/RP2350, SAMD21, MG24, nRF54L15, RA4M1). Requires /xiao skill for board-specific pin definitions. Covers board setup, ESP32/nRF/RP specific APIs (WiFi, BLE, PIO), common Arduino libraries (Wire, SPI, Servo, WiFiClient, HTTPClient, PubSubClient), and project examples.

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	Board Manager Package	Getting Started
ESP32C3	"esp32" by Espressif	getting-started/esp32c3.md
ESP32C5	"esp32" by Espressif	getting-started/esp32c5.md
ESP32C6	"esp32" by Espressif	getting-started/esp32c6.md
ESP32S3	"esp32" by Espressif	getting-started/esp32s3.md
nRF52840	"Adafruit nRF52"	getting-started/nrf52840.md
RP2040	"Raspberry Pi Pico"	getting-started/rp2040.md
RP2350	"Raspberry Pi RP2350"	getting-started/rp2350.md
SAMD21	"Seeed SAMD Boards"	getting-started/samd21.md
MG24	"Seeed nRF52"	getting-started/mg24.md
nRF54L15	NOT SUPPORTED	See MicroPython skill (/xiao-micropython)
RA4M1	"Seeed SAMD Boards"	getting-started/ra4m1.md

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

Library	Reference
Wire (I2C)	libraries/wire.md
SPI	libraries/spi.md
Serial/HardwareSerial	libraries/serial.md
SoftwareSerial	libraries/softwareserial.md

Networking (ESP32)

Library	Reference
WiFi	api/esp32-wifi.md
WiFiClient	libraries/wifi-client.md
HTTPClient	libraries/http-client.md
PubSubClient (MQTT)	libraries/mqtt-client.md
WebSockets	libraries/websocket.md

Actuators

Library	Reference
Servo	libraries/servo.md
Stepper	libraries/stepper.md

Storage

Library	Reference
EEPROM	libraries/eeprom.md
Preferences (ESP32)	libraries/preferences.md
SPIFFS/LittleFS	libraries/spiffs.md
SD	libraries/sd.md

Sensors

Library	Reference
DHT/DHT22	libraries/dht.md
Adafruit BME280	libraries/bme280.md
Adafruit MPU6050	libraries/mpu6050.md
Adafruit Unified Sensor	libraries/adafruit-sensor.md

Displays

Library	Reference
Adafruit GFX	libraries/adafruit-gfx.md
Adafruit SSD1306 (OLED)	libraries/ssd1306.md
Adafruit ST7789 (TFT)	libraries/st7789.md
U8g2 (Universal)	libraries/u8g2.md

Expansion Boards

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

Expansion Board	Key Features	Reference
Expansion Base	OLED, RTC, SD card, buzzer, Grove connectors	expansion-boards/expansion-base.md
Round Display	1.28" touchscreen (240x240)	expansion-boards/round-display.md
Grove Shield	8 Grove connectors + battery management	expansion-boards/grove-shield.md
ePaper V2	7 ePaper display sizes (1.54" to 7.5")	expansion-boards/epaper-v2.md
CAN Bus	MCP2515 controller for automotive/industrial	expansion-boards/can-bus.md
RS485	Industrial communication	expansion-boards/rs485.md
LED Driver	5V/12V LED strips with WLED support	expansion-boards/led-driver.md
Bus Servo	Serial bus servo control for robotics	expansion-boards/bus-servo.md
GPS/GNSS	L76K GNSS module for positioning	expansion-boards/gps-gnss.md
GPIO Expander	MCP23017 16-bit I/O expansion	expansion-boards/gpio-expander.md
RGB Matrix	RGB LED matrix driver	expansion-boards/rgb-matrix.md
COB LED	Chip-on-Board LED lighting	expansion-boards/cob-led.md

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

Error	Solution
No such file or directory	Install missing library: arduino-cli lib install <libname>
'WiFi' was not declared	Add #include <WiFi.h> at top of sketch
expected ';' before '}'	Check syntax, add missing semicolon
undefined reference to	Add required library or check function name

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

Setting	Options	Recommended
CPU Frequency	160MHz, 240MHz	240MHz for max performance
Core Debug Level	None, Verbose	None (release)
PSRAM	OPI/QSPI	If available
Flash Mode	QIO, QOUT	Default
Partition Scheme	Default, OTA	Default for most projects
Upload Speed	921600	Max stable speed
USB CDC On Boot	Enabled, Disabled	Enabled for Serial

nRF52 Board Manager Settings

Setting	Options	Recommended
SoftDevice	S140, S132	S140 for BLE
Debug	None, Minimal	None (release)
LFO (RC Oscillator)	Enabled, Disabled	Enabled

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