Automatic College Bell with Raspberry Pi and PHP

Introduction
#

In today’s digital age, automation has become a cornerstone of efficient institutional management. One area where automation can significantly improve operations is in educational institutions’ bell systems. Traditional manual bell systems are prone to human error, timing inconsistencies, and require constant attention. This project presents a complete solution for an Automatic College Bell Management System built using Raspberry Pi, PHP, and MySQL.

What is This Project?
#

The Automatic College Bell System is an open-source solution designed to replace manual bell operations in educational institutions. It provides:

Automated bell scheduling for different days of the week
Multiple bell types: Long bells, short bells, and prayer announcements
Web-based management interface for easy configuration
Reliable timing using system cron jobs
Scalable architecture that can be deployed on Raspberry Pi or any Linux machine

System Architecture
#

The system follows a simple yet effective flow:

Raspberry Pi/Linux → Application → Mixer → Amplifier → PA System

Core Components
#

Hardware Layer: Raspberry Pi or Linux machine with audio output
Application Layer: PHP-based web application with MySQL database
Audio Layer: Audio files (WAV format) for different bell sounds
Control Layer: Cron jobs and system services for automation

Technical Implementation
#

Database Schema
#

The system uses two main database tables:

BELL_TIME Table
#

BT_BELL_ID: Unique identifier for each bell configuration
BT_DAY: Day of the week (Mon, Tue, Wed, etc.)
BT_TIME: Comma-separated time slots with bell types
BT_PRAYER_SONG: Path to prayer audio file

USERS Table
#

U_USER_ID: User identifier
U_NAME: User’s full name
U_USER_NAME: Login username
U_PASSWORD: Encrypted password

Bell Time Format
#

The system uses a character-based encoding for different bell types:

“L”: Long bell (typically for class start/end)
“S”: Short bell (for period transitions)
“P”: Prayer announcement

Example time format: 08:50L,08:54S,08:55P,09:00S

Core PHP Scripts
#

bell.php
#

The main automation script that:

Checks current time and day
Queries the database for scheduled bells
Copies appropriate audio files to the play directory
Runs every minute via cron job

run.sh
#

A bash script that:

Monitors the play directory for new audio files
Plays audio using aplay command
Cleans up played files
Runs continuously as a system service

Installation Guide
#

Prerequisites
#

Before installing the system, ensure you have the following installed on your Raspberry Pi or Linux machine:

# Update system packages
sudo apt update && sudo apt upgrade -y

# Install Apache web server
sudo apt install apache2 -y

# Install PHP and required extensions
sudo apt install php php-cli php-mysql php-mbstring -y

# Install MySQL server
sudo apt install mysql-server -y

# Install phpMyAdmin for database management
sudo apt install phpmyadmin -y

Installation Steps
#

Clone or Download the Project

cd /var/www/html
sudo git clone https://github.com/iam-vivekus/automatic_college_bell.git bell
sudo chown -R www-data:www-data bell
sudo chmod -R 755 bell

Set Up Database

Note: This setup creates the database manually instead of importing an SQL file, giving you full control over the database structure and initial data.

# Access MySQL
sudo mysql -u root -p

# Create database
CREATE DATABASE BELL;
USE BELL;

# Create BELL_TIME table
CREATE TABLE BELL_TIME (
  BT_BELL_ID int(20) NOT NULL,
  BT_DAY varchar(50) NOT NULL,
  BT_TIME varchar(800) NOT NULL,
  BT_PRAYER_SONG varchar(500) NOT NULL,
  PRIMARY KEY (BT_DAY)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

# Create USERS table
CREATE TABLE USERS (
  U_USER_ID int(10) NOT NULL,
  U_NAME varchar(50) NOT NULL,
  U_USER_NAME varchar(50) NOT NULL,
  U_PASSWORD varchar(50) NOT NULL,
  PRIMARY KEY (U_USER_ID)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

# Create admin user
INSERT INTO USERS (U_USER_ID, U_NAME, U_USER_NAME, U_PASSWORD) 
VALUES (1, 'BELL', 'admin', '1234');

# Insert sample bell schedules (optional)
INSERT INTO BELL_TIME VALUES 
(1,'Mon','08:50L,08:54S,08:55P,09:00S,09:50S,10:40S,10:55S,11:45S,12:35S,13:25S,14:15S,15:10S,15:20S,16:00L','/var/www/html/bell/song1.wav'),
(2,'Tue','08:50L,08:54S,08:55P,09:00S,09:50S,10:40S,10:55S,11:45S,12:35S,13:25S,14:15S,15:10S,15:20S,16:00L','/var/www/html/bell/song2.wav'),
(3,'Wed','08:50L,08:54S,08:55P,09:00S,09:50S,10:40S,10:55S,11:45S,12:35S,13:25S,14:15S,15:10S,15:20S,16:10N','/var/www/html/bell/song3.wav'),
(4,'Thu','08:50L,08:54S,08:55P,09:00S,09:50S,10:40S,10:55S,11:45S,12:35S,13:25S,14:15S,15:10S,15:20S,16:10N','/var/www/html/bell/song4.wav'),
(5,'Fri','08:50L,08:54S,08:55P,09:00S,09:55S,10:50S,11:05S,12:00S,12:55S,14:00S,15:00S,15:20S,16:10N','/var/www/html/bell/song1.wav'),
(6,'Sat','08:50L,08:54S,08:55P,09:00S,09:50S,10:40S,10:55S,11:45S,12:35S,13:25S,14:15S,15:10S,15:20S,16:10N','/var/www/html/bell/song2.wav'),
(7,'Sun','','/var/www/html/bell/song3.wav');

Configure Database Connection Edit config.php with your database credentials:

<?php
$conn = mysqli_connect("localhost", "your_username", "your_password", "BELL");
?>

Set Up System Service Create a systemd service for the audio player:

sudo nano /etc/systemd/system/bell-player.service

Add the following content:

[Unit]
Description=Bell System Audio Player
After=network.target

[Service]
Type=simple
User=www-data
WorkingDirectory=/var/www/html/bell
ExecStart=/var/www/html/bell/run.sh
Restart=always

[Install]
WantedBy=multi-user.target

Enable and start the service:

sudo systemctl enable bell-player
sudo systemctl start bell-player

Configure Cron Job Set up automatic bell checking:
```
sudo crontab -e
```
Add this line:
```
* * * * * php /var/www/html/bell/bell.php
```
Audio Setup Ensure your audio files are in the correct location:
- /var/www/html/bell/bell/short_bell.wav
- /var/www/html/bell/bell/long_bell.wav
- /var/www/html/bell/song1.wav (prayer song1)
- /var/www/html/bell/song2.wav (prayer song2)
- /var/www/html/bell/song3.wav (prayer song3)
- /var/www/html/bell/song4.wav (prayer song4)

Usage Guide
#

Accessing the Web Interface
#

Open your web browser and navigate to: http://your-raspberry-pi-ip/bell
Login with the default credentials:
- Username: admin
- Password: 1234

Main Features
#

Home Dashboard
#

The main interface provides access to:

Long Bell: Manual trigger for long bell sound
Short Bell: Manual trigger for short bell sound
Prayer: Manual trigger for prayer announcement
Edit Bell: Configure bell schedules

Bell Schedule Management
#

The “Edit Bell” section allows you to:

Set different schedules for each day of the week
Configure multiple time slots per day
Choose bell types for each time slot:
- L: Long bell
- S: Short bell
- P: Prayer
- N: No bell

Example Schedule Configuration
#

For a typical school day (Monday):

08:50L,08:54S,08:55P,09:00S,09:50S,10:40S,10:55S,11:45S,12:35S,13:25S,14:15S,15:10S,15:20S,16:00L

This schedule includes:

8:50 AM: Long bell (class start)
8:54 AM: Short bell (warning)
8:55 AM: Prayer
9:00 AM: Short bell (first period)
… and so on

Customization Options
#

Audio Files
#

You can replace the default audio files with your institution’s preferred sounds:

Replace short_bell.wav and long_bell.wav in the bell/ directory
Update prayer songs (song1.wav, song2.wav, etc.)
Ensure all audio files are in WAV format for compatibility

Schedule Flexibility
#

The system supports:

Different schedules for each day of the week
Multiple time slots per day
Easy modification through the web interface
No programming knowledge required for schedule changes

Network Access
#

For remote management:

Configure port forwarding on your router
Set up SSL certificates for secure access
Use strong passwords for admin accounts

Troubleshooting
#

Common Issues
#

Bells Not Ringing
- Check if the cron job is running: sudo crontab -l
- Verify the bell-player service: sudo systemctl status bell-player
- Check audio permissions and hardware connections
Web Interface Not Loading
- Verify Apache is running: sudo systemctl status apache2
- Check file permissions: sudo chown -R www-data:www-data /var/www/html/bell
- Ensure PHP is properly installed
Database Connection Issues
- Verify MySQL is running: sudo systemctl status mysql
- Check database credentials in config.php
- Ensure the BELL database exists

Logs and Monitoring
#

# Check system service logs
sudo journalctl -u bell-player -f

# Check Apache logs
sudo tail -f /var/log/apache2/error.log

# Check cron job execution
sudo grep CRON /var/log/syslog

Security Considerations
#

Change Default Passwords: Immediately change the default admin password
Network Security: Use strong passwords and consider VPN access
Regular Updates: Keep the system and dependencies updated
Backup: Regularly backup the database and configuration files

Future Enhancements
#

The system can be extended with:

Mobile App: Remote management via smartphone
Multiple Zones: Support for different buildings/areas
Integration: Connect with school management systems
Analytics: Bell usage statistics and reports
Weather Integration: Adjust schedules based on weather conditions

Conclusion
#

This Automatic College Bell System provides a robust, scalable solution for educational institutions looking to modernize their bell operations. With its web-based interface, flexible scheduling, and reliable automation, it eliminates the need for manual bell management while providing greater control and customization options.

The open-source nature of the project allows for community contributions and continuous improvement. Whether you’re a small school or a large university, this system can be adapted to meet your specific requirements.

For more information, visit the project repository: https://github.com/iam-vivekus/automatic_college_bell.git

This project demonstrates the power of combining simple hardware with smart software to solve real-world problems in educational institutions.

Author

Vivek US

A Tech Enthusiast

Introduction#

What is This Project?#

System Architecture#

Core Components#

Technical Implementation#

Database Schema#

BELL_TIME Table#

USERS Table#

Bell Time Format#

Core PHP Scripts#

bell.php#

run.sh#

Installation Guide#

Prerequisites#

Installation Steps#

Usage Guide#

Accessing the Web Interface#

Main Features#

Home Dashboard#

Bell Schedule Management#

Example Schedule Configuration#

Customization Options#

Audio Files#

Schedule Flexibility#

Network Access#

Troubleshooting#

Common Issues#

Logs and Monitoring#

Security Considerations#

Future Enhancements#

Conclusion#