Xiao ESP32C3 - Hardware Guide

📋 Xiao ESP32C6 Overview

The Xiao ESP32C6 is a compact WiFi-enabled microcontroller with improved capabilities:

Specification	Details
Processor	ESP32-C6 (Dual Core, 160MHz)
RAM	400KB
Flash	4MB
WiFi	802.11 b/g/n (2.4GHz)
USB	USB-C
GPIO Pins	11 total (we use 4 for LEDs)
Power Supply	5V USB or 3.3V external

📌 Pinout Diagram

┌─────────────────────────────────────┐ │ Xiao ESP32C3 Pinout │ │ │ │ USB-C Port (Top) │ │ ──────────────── │ │ │ │ 5V GND GPIO0 GPIO1 │ Left Side │ ● ● ● ● │ │ │ │ GPIO4 GPIO5 GPIO6 GPIO7 │ Right Side │ ● ● ● ● │ │ │ │ GND 3.3V GPIO2 GPIO3 │ Bottom │ ● ● ● ● │ │ │ └─────────────────────────────────────┘

Note: Exact pinout may vary. Verify with official Seeed documentation for your specific board revision.

💡 LED Pin Configuration

In this project, 4 LEDs are controlled using the following GPIO pins:

GPIO 0

LED 1 (Red)

Pin 6 on physical board

GPIO 1

LED 2 (Cyan)

Pin 7 on physical board

GPIO 2

LED 3 (Blue)

Pin 11 on physical board

GPIO 3

LED 4 (Orange)

Pin 12 on physical board

⚠️ Important: If these GPIO pins are already in use or conflict with your setup, modify the LED_PINS array in the Arduino code:

const int LED_PINS[4] = {0, 1, 2, 3}; // Change these numbers

🔌 LED Wiring Guide

Components Needed (per LED)

1x LED (any color)
1x 220Ω resistor (¼W)
Connecting wires
Breadboard (optional but recommended)

Wiring for Each LED

GPIO Pin (from ESP32C3) │ ├──→ [220Ω Resistor] │ ├──→ (+) LED Anode (Long Leg) │ └──→ (-) LED Cathode (Short Leg) │ └──→ GND (Ground from ESP32C3)

Full Connection Schematic

Xiao ESP32C3 Breadboard ┌──────────────┐ │ │ │ GPIO 0 ────┼─────[220Ω]─────┌─(+)LED1(-)─┐ │ GPIO 1 ────┼─────[220Ω]─────├─(+)LED2(-)─┤ │ GPIO 2 ────┼─────[220Ω]─────├─(+)LED3(-)─┤ │ GPIO 3 ────┼─────[220Ω]─────├─(+)LED4(-)─┤ │ │ │ │ │ GND ───────┼────────────────└────────────┘ │ │ └──────────────┘

💡 Tip: Use a breadboard to organize connections neatly. This makes troubleshooting easier and prevents accidental short circuits.

👣 Step-by-Step Connection Instructions

Step 1: Prepare the LEDs

✓ Identify the long leg (anode/+) and short leg (cathode/-) of each LED

✓ Bend the legs if needed for easier breadboard insertion

Step 2: Connect Power and Ground Rails

✓ Connect Xiao's GND pin to the ground rail on the breadboard

✓ This creates a common ground for all LEDs

Step 3: Install Resistors

✓ Insert a 220Ω resistor into the breadboard for each LED

✓ One end connects to the GPIO pin, other end to LED anode

Step 4: Connect LEDs

✓ Connect LED anode (+) to the resistor output

✓ Connect LED cathode (-) to the ground rail

Step 5: Verify Connections

✓ Double-check each LED cathode is connected to ground

✓ Verify resistors are in series between GPIO and LED

✓ No loose wires should touch each other

Step 6: Power Up

✓ Connect Xiao ESP32C3 to computer via USB-C

✓ LEDs should not light up initially (GPIO pins are LOW)

🔬 Resistor Selection

The 220Ω resistor limits current to safe levels for the GPIO pins and LEDs.

LED Color	Typical Forward Voltage	Recommended Resistor
Red	2.0V	220Ω - 470Ω
Green	2.2V	220Ω - 470Ω
Blue/Cyan	3.2V	150Ω - 220Ω
Yellow	2.1V	220Ω - 470Ω

Calculation for Red LED:
- ESP32 GPIO Output: 3.3V
- LED Forward Voltage: 2.0V
- Voltage Drop Across Resistor: 3.3V - 2.0V = 1.3V
- Desired LED Current: ~20mA
- Resistor Value: R = V/I = 1.3V / 0.02A = 65Ω

Practical values (use nearest standard resistor):
- 220Ω for safety (brighter = less resistor, dimmer = more resistor)
- 470Ω for dimmer LEDs
- 150Ω for maximum brightness (not recommended for safety)
      

⚡ Power Consumption

Component	Current Draw
Xiao ESP32C3 (Idle)	~20mA
Xiao ESP32C3 (WiFi Active)	~100-200mA
Single LED (with 220Ω resistor)	~15mA
All 4 LEDs ON	~60mA
Total (WiFi + 4 LEDs)	~260mA Maximum

💡 Note: A standard USB port provides 500mA at 5V. Your setup will work fine with USB power. For battery operation, use at least 1000mAh capacity.

🔧 Troubleshooting

❌ LED doesn't light up

Verify LED polarity (long leg to resistor, short leg to ground)
Check resistor is properly installed
Test LED with battery to confirm it's not burned out
Verify GPIO pin number matches the code
Use Serial Monitor to check if GPIO pin is set HIGH

❌ LED always on (won't turn off)

GPIO pin may be pulled up to 3.3V by default
Check code logic - is digitalWrite correct?
Try inverting the logic (HIGH to LOW)

❌ LED is dim

Try smaller resistor (220Ω instead of 470Ω)
Check WiFi interference (try near router)
Verify power supply voltage (should be 5V or 3.3V)

❌ Multiple LEDs interfere with each other

Ensure all LEDs share the same GND connection
Use separate ground path for each resistor (not daisy-chained)
Add decoupling capacitor (0.1µF) between 3.3V and GND near the chip

⚠️ Safety Precautions

DO NOT:

Connect GPIO pins directly to 5V without a resistor
Reverse LED polarity (can damage the LED and GPIO pin)
Use resistors smaller than 150Ω (excessive current can damage GPIO)
Allow bare wires to touch each other (short circuit)
Connect high-current devices (motors, relays) directly to GPIO

DO:

Always use appropriate resistors in series with LEDs
Connect a common ground between ESP32 and all circuits
Use a breadboard to organize connections neatly
Test connections before powering on
Keep WiFi antenna away from high-current wiring

🧪 Testing Your Setup

Test 1: Hardware Test with Arduino IDE

Upload this simple test sketch to verify GPIO pins work:

void setup() {
  Serial.begin(115200);
  pinMode(0, OUTPUT);
  pinMode(1, OUTPUT);
  pinMode(2, OUTPUT);
  pinMode(3, OUTPUT);
}

void loop() {
  digitalWrite(0, HIGH);
  delay(500);
  digitalWrite(0, LOW);
  delay(500);
  // Repeat for pins 1, 2, 3
}
      

Test 2: Check WiFi Connection

Ensure ESP32 connects to your WiFi network and verify the IP address via Serial Monitor

Test 3: Test API Endpoints

Use curl or web browser to test endpoints:

# Check device is reachable
ping 192.168.1.100

# Test API
curl http://192.168.1.100/status
curl http://192.168.1.100/led1/on
curl http://192.168.1.100/info
      

Test 4: Full System Test

Open page 1.html in browser and test all LED buttons

🚀 Advanced Modifications

Add More LEDs

The Xiao ESP32C3 has enough GPIO pins for up to 8 LEDs. Modify the code:

// In esp32_led_controller.ino
const int LED_PINS[8] = {0, 1, 2, 3, 5, 6, 7, 21};  // Up to 8 LEDs
      

Use PWM for Brightness Control

Replace digitalWrite with analogWrite for brightness control:

// Brightness 0-255
analogWrite(LED_PINS[0], 128);  // 50% brightness
      

Add Button Control

Connect a physical button to GPIO pin 4 for manual LED control

Temperature Monitoring

Add temperature sensor (DHT11/BME280) to monitor environment

🔧 Xiao ESP32C6 LED Controller - Hardware Guide