Raspberry Pi Temperature & Humidity Monitor

This project uses a Raspberry Pi and a DHT22 sensor to log temperature and humidity data to a local database and display it on a beautiful web dashboard.

🚀 Features

• Automated Logging: Reads sensor data every minute.
• Data Persistence: Stores readings in a lightweight SQLite database.
• Web Dashboard: View real-time values and historical graphs on any device in your local network.
• Modern UI: Dark mode, responsive design, and interactive charts.

🛠 Hardware Required

• Raspberry Pi (3B+, 4, or Zero W)
• DHT22 Sensor (AM2302)
• Jumper Wires (Female-to-Female or Female-to-Male depending on your header)

🔌 Wiring

Connect the DHT22 sensor to the Raspberry Pi:

DHT22 Pin	Raspberry Pi Pin
VCC (+)	3.3V (Pin 1)
GND (-)	GND (Pin 9)
DATA	GPIO 4 (Pin 7)

Note

If you are using a bare DHT22 module (white grid), you may need a 10k resistor between VCC and DATA. Most PCB-mounted modules (blue/black board) already include this.

💿 Installation

1. Clone or Copy the Code Download this project to your Raspberry Pi, preferably at /home/pi/pi_temp_sensor.

2. Install System Dependencies The Adafruit DHT library requires libgpiod3 and python3-pip.

   sudo apt-get update
   sudo apt-get install -y python3-pip libgpiod3

3. Install Python Dependencies

   # Create a virtual environment (Recommended)
   python3 -m venv venv
   source venv/bin/activate
   
   # Install requirements
   pip install -r requirements.txt

   If you cannot create a virtualenv, you can install globally with pip3 install --break-system-packages -r requirements.txt (Raspberry Pi OS Bookworm+ requirement).

🏃 Running the Application

Method 1: Manual Run (Testing)

Open two terminal windows:

Terminal 1 (Logger):

python3 logger.py

You should see temperature readings printed to the console.

Terminal 2 (Web Server):

python3 app.py

Access the dashboard at http://<YOUR_PI_IP>:5000

Method 2: Systemd Service (Auto-start on Boot)

1. Edit the Service Files Check sensor-logger.service and sensor-web.service to ensure the paths match your installation (default assumes /home/pi/pi_temp_sensor).

2. Install Services

   sudo cp sensor-logger.service /etc/systemd/system/
   sudo cp sensor-web.service /etc/systemd/system/
   
   sudo systemctl daemon-reload
   sudo systemctl enable sensor-logger
   sudo systemctl enable sensor-web
   sudo systemctl start sensor-logger
   sudo systemctl start sensor-web

3. Check Status

   sudo systemctl status sensor-logger
   sudo systemctl status sensor-web

📊 Usage

Navigate to http://raspberrypi.local:5000 or http://<IP_ADDRESS>:5000 in your browser. The charts will update every minute with new data properly stored in sensor_data.db.

🐛 Troubleshooting

• "Failed to retrieve data": DHT22 sensors can be finicky. The script retries automatically. Check wiring if it fails constantly.
• Permission Errors: Ensure the user running the script has GPIO access (gpio group).