Decibel Meter Project

A smart Decibel Meter based on ESP32-C3, featuring a round LCD display with a modern UI built using LVGL, and a web interface for remote monitoring and historical data analysis.

Features

• Real-time Sound Level Measurement: Measures ambient noise levels in decibels (dB).
• Dual UI Modes:
  • Gauge View: Analog-style gauge with current dB value and a "peak hold" indicator (red dot) that retains the maximum value for 2 seconds.
  • History Chart: Displays a bar chart of the last 2 hours of noise levels (5-minute resolution).
  • Auto-Switching: The display automatically toggles between the Gauge and History view every 30 seconds.
• Web Interface:
  • Built-in web server accessible via local network.
  • Real-time historical chart visualization using Chart.js.
  • JSON API endpoint (/api/history) for data retrieval.
• OTA Updates: Supports Over-The-Air firmware updates.
• Round Display Support: UI optimized for 160x160 round TFT displays.

Hardware Requirements

• Microcontroller: Seeed Studio XIAO ESP32C3 (or compatible ESP32-C3 board).
• Display: Round TFT LCD (160x160 resolution) driven by TFT_eSPI (GC9A01 driver).
• Microphone: I2S Microphone (e.g., INMP441).

Wiring

graph LR
    MCU[ESP32-C3]
    
    subgraph Display [GC9A01 Display]
        D_MOSI[MOSI]
        D_SCLK[SCLK]
        D_CS[CS]
        D_DC[DC]
        D_RST[RST]
    end

    subgraph Mic [INMP441 Microphone]
        M_WS[WS]
        M_SD[SD]
        M_SCK[SCK]
    end

    MCU -- GPIO 7 --> D_MOSI
    MCU -- GPIO 6 --> D_SCLK
    MCU -- GPIO 5 --> D_CS
    MCU -- GPIO 4 --> D_DC
    MCU -- GPIO 8 --> D_RST

    MCU -- GPIO 3 --> M_WS
    MCU -- GPIO 10 --> M_SD
    MCU -- GPIO 2 --> M_SCK

Loading

Display (GC9A01)

Pin	ESP32-C3 GPIO
MOSI (SDA)	7
SCLK (SCL)	6
CS	5
DC	4
RST	8
VCC	3.3V
GND	GND

Microphone (INMP441)

Pin	ESP32-C3 GPIO
WS (LRC)	3
SD (DOUT)	10
SCK (BCLK)	2
VCC	3.3V
GND	GND

Software Dependencies

The project is built using PlatformIO and depends on the following libraries:

• LVGL (v9.4.0): For the graphical user interface.
• TFT_eSPI: For display driving (included in lib/).
• ArduinoOTA: For wireless firmware updates.
• WebServer: For the HTTP interface.

Installation

1. Clone the repository:

   git clone https://github.com/HalfbitStudio/Decibelmeter.git
   cd Decibelmeter

2. Configure WiFi: Open include/network.h (or src/network.cpp depending on implementation) and set your WiFi credentials:

   const char* ssid = "YOUR_WIFI_SSID";
   const char* password = "YOUR_WIFI_PASSWORD";

3. Build and Upload: Connect your ESP32-C3 via USB and run:

   pio run --target upload

4. OTA Upload (Optional): If the device is already running and connected to WiFi, you can upload via OTA:

   pio run --target upload --environment esp32-c3-devkitm-1-ota

   Note: Default OTA password is set in platformio.ini.

Usage

On Device

• Power on the device.
• The splash screen will appear, followed by the connection status.
• Once connected, the main Gauge View will appear.
• The screen will automatically switch to the History Chart every 30 seconds.

Web Interface

• Find the IP address of the device (monitor the serial output on boot or check your router).
• Open a web browser and navigate to http://<DEVICE_IP>/.
• You will see a live chart of the recorded sound levels.

Project Structure

• src/main.cpp: Main entry point, setup, and loop.
• src/ui.cpp: LVGL UI implementation (Gauge, Chart, Animations).
• src/web_server.cpp: Web server logic and history data management.
• src/audio_processing.cpp: dB calculation logic.
• src/microphone.cpp: I2S microphone handling.
• src/network.cpp: WiFi and OTA management.
• include/lv_conf.h: LVGL configuration file.
• include/history_storage.h: History storage API (SPIFFS persistence)
• src/history_storage.cpp: SPIFFS-based load/save logic for chart history.

License

Copyright (c) Halfbit Studio. All rights reserved.