Noise Traffic Light 🚦

A real-time noise monitor that displays sound levels as a traffic light using RGB LEDs.

📋 Features

• Real-time noise detection via I2S MEMS microphone
• 3-color traffic light display:
  • 🟢 GREEN – Noise is low (quieter than threshold)
  • 🟡 YELLOW – Noise is moderate (within range)
  • 🔴 RED – Noise is high (exceeded threshold)
• 12 NeoPixel RGB LED strip for bright, visible feedback
• A-weighted sound level measurement (dBA) for realistic perception
• Configurable thresholds via persistent storage

🔧 Hardware Setup

Pin Configuration

Component	Pin	Color	Description
WS2812 LED Data	GPIO 2	-	NeoPixel strip (12 LEDs)
I2S L/R Select	GPIO 4	Green	Microphone channel select (set HIGH = RIGHT channel)
I2S Word Select	GPIO 5	Blue	Microphone L/R clock
I2S Serial Clock	GPIO 6	White	Microphone bit clock
I2S Serial Data	GPIO 7	Yellow	Microphone audio data
Power (5V)	5V	-	USB power supply
GND	GND	-	Ground

Wiring Diagram

ESP32                          I2S Microphone (e.g., INMP441)
───────                        ──────────────────
GPIO 4 (green, HIGH)───────────→ L/R (channel select = RIGHT)
GPIO 5 (blue) ─────────────────→ WS (L/R Clock)
GPIO 6 (white) ─────────────────→ SCK (Bit Clock)
GPIO 7 (yellow)─────────────────→ SD (Serial Data)
GND ───────────────────────────→ GND
3V3 ───────────────────────────→ VDD (if 3.3V version)

ESP32                          NeoPixel Strip (WS2812)
───────                        ──────────────────
GPIO 2 ────────────────────────→ DI (Data In)
5V ────────────────────────────→ 5V
GND ───────────────────────────→ GND

📊 How It Works

Audio Processing Pipeline

1. I2S Sampling (48 kHz, 32-bit)

   • Captures continuous audio from the microphone
   • High-precision digital sampling

2. IIR Filtering

   • Equalizer filter (INMP441): Flattens microphone frequency response
   • A-weighting filter: Mimics human ear sensitivity (emphasizes mid-frequencies)

3. Sound Level Calculation

   • Converts filtered samples to dB (decibels)
   • Uses microphone calibration: 94 dB SPL reference
   • LEQ (Equivalent Continuous Sound Level) over 0.15 second blocks

4. Decision Logic

   if (Leq < dB_min)     → GREEN   (quiet)
   if (dB_min ≤ Leq < dB_max) → YELLOW  (moderate)
   if (Leq ≥ dB_max)     → RED     (loud)
   

🎚️ Configuration

Default Thresholds

dB_min_default = 40   // Below 40 dB → GREEN
dB_max_default = 60   // Above 60 dB → RED

Recommended Settings

Environment	dB_min	dB_max	Notes
Library/Silent	30	50	Very quiet spaces
Classroom	40	60	Normal teaching
Active classroom	45	70	Group work sessions
Workshop	60	80	Tolerate machinery

🌐 WiFi & Web Configuration

Access Point Mode

The device operates as a WiFi Access Point (AP) that you can connect to:

• SSID (Network Name): NoiseLight
• Password: 12345678
• IP Address: 192.168.4.1
• Port: 80 (HTTP)

Setup Instructions

1. Connect to the device's WiFi:

   • Open your device's WiFi settings (phone, tablet, laptop)
   • Select network NoiseLight
   • Enter password: 12345678

2. Open the configuration page:

   • Open browser and go to: http://192.168.4.1
   • The web interface will load automatically

3. Configure settings in real-time:

   • Live dB level display updates every 200ms
   • All sliders update preview instantly
   • Press Save Configuration to persist settings to device storage

Web Interface Features

Display Mode

• Traffic Light: All LEDs show single color (GREEN/YELLOW/RED)
• VU Meter: LEDs create gradient bar showing sound intensity

LED Settings

• Brightness: 0–255 (default: 57)
• Color Selection: Choose custom colors for each noise level

Switchover Points (dB)

• Floor Level: Noise floor baseline (default: 37 dB)
• Green→Yellow: Transition threshold (default: 52 dB)
• Yellow→Red: Alert threshold (default: 62 dB)
• Color Preview: Visual bar shows LED colors across dB range

Response Timing

• Decay Time: How long to hold current color after sound stops (0–3000 ms, default: 2400 ms)
• Response Time: Minimum update interval between LED changes (0–500 ms, default: 50 ms)

Persistent Storage

All configuration changes are automatically saved to ESP32's NVS (Non-Volatile Storage):

• Settings survive power loss
• Load automatically on device startup
• Accessible via /api/config endpoint

🚀 Building & Uploading

Prerequisites

• PlatformIO (VS Code extension or CLI)
• Arduino IDE (optional, for direct compilation)

Build

# Using PlatformIO
platformio run -e esp32-s3-devkitc1-n4r2

# Or in VS Code: Ctrl+Shift+B → Build

Upload

# Using PlatformIO
platformio run -t upload -e esp32-s3-devkitc1-n4r2

# Or in VS Code: Ctrl+Shift+B → Upload

📈 Serial Output

The device outputs dB measurements to the serial monitor (115200 baud):

Leq: 45.3 dB | Min: 40 | Max: 60 | GREEN
Leq: 62.1 dB | Min: 40 | Max: 60 | RED
Leq: 55.2 dB | Min: 40 | Max: 60 | YELLOW

🔧 Calibration

Microphone Sensitivity

If readings are consistently off:

1. Measure known sound level (e.g., using phone app)
2. Compare with serial output
3. Adjust MIC_OFFSET_DB in main.cpp:

   #define MIC_OFFSET_DB 3.0103  // Increase/decrease calibration offset

Optimal Setup

• Mount microphone in center of room
• Avoid placing near walls or corners (reflections)
• Keep away from vibration sources
• Ensure clear air path (not covered)

🔴 Troubleshooting

Issue	Cause	Solution
Always GREEN	Microphone not connected	Check I2S pins (GPIO 4,6,7)
Always RED	Calibration off	Adjust MIC_OFFSET_DB
No serial output	Wrong baud rate	Set to 115200
No LED response	Wrong LED pin	Verify GPIO 2 connection
Microphone noise floor high	Electrical noise	Shield data lines, check power supply

📚 References

• Original deciLight Project: https://github.com/bbbenji/deciLight
• FastLED Documentation: http://fastled.io/
• ESP-IDF I2S API: https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/i2s.html
• A-weighting Filter: https://en.wikipedia.org/wiki/A-weighting

📝 License

This project is adapted from deciLight (GPL-3.0). Licensed under GNU General Public License v3.0.

🎨 Future Enhancements

• IR remote control for threshold adjustment
• MQTT integration for remote monitoring
• WiFi display (web dashboard)
• Multiple noise zones (classroom network)
• Adjustable color mapping
• Sound event logging