Real-Time Heart Rate Monitor

🌐 Language / Dil: 🇬🇧 English | 🇹🇷 Türkçe

Real-Time Heart Rate Monitor

Bluetooth Low Energy (BLE) heart rate monitor: Android app + PHP server. Real-time data collection from Polar and other BLE-compatible heart rate sensors, server synchronization, and live monitoring via web dashboard.

Component	Technology	Location
Android App	Kotlin, Jetpack Compose	`app/`
Web Dashboard	PHP, Chart.js, SSE	`server/`

Screenshots

Live Heart Rate Screen

The main screen displays live heart rate data from the BLE sensor. Includes connection status, battery level, sensor contact, and signal quality indicators.

Charts and Daily Statistics

Monitor heart rate graphs and RR intervals (ECG-like) in real-time. Daily minimum, average, and maximum values are displayed.

Hourly Charts

Analyze heart rate data throughout the day with hourly charts.

Hourly Summary Table

Detailed table showing minimum, average, maximum values and record count for each hour.

All Records

List and review all heart rate records sent to the server.

Device Mode Settings

Server Mode: Collects data from BLE sensor and sends to server. Client Mode: Monitors live data via WebView (while another device runs in Server mode).

You can also configure heart rate threshold values from this screen.

Alert and Service Settings

Configure vibration and sound alerts for threshold violations. Background service auto-start option.

API Settings

Configure server URL and API key. The app can work with your own server.

Features

BLE Connection

Wahoo TICKR Fit and BLE Heart Rate Profile compatible devices
Easily integrates with other sensors (Polar, Garmin, etc.) using standard BLE HR Profile
Automatic reconnection
Battery level monitoring
Sensor contact detection
RR intervals (beat-to-beat) reading

Data Analysis

Real-time heart rate chart
RR intervals chart (ECG-like)
Daily min/average/max statistics
Detailed hourly analysis
Signal quality calculation (HRV-based)

Server Synchronization

Data transmission via REST API
Offline mode (local storage when no connection)
Configurable API URL and key
Live monitoring via WebView (Client mode)

Alerts

Threshold violation notifications (low/high heart rate)
Vibration and sound alerts
Customizable threshold values

Background Service

Continuous operation with Foreground Service
Battery optimization management
Manufacturer-specific battery settings guide
Auto-start option

Multi-Language Support

Turkish and English interface
Automatic system language detection
Manual language switching from Settings
Easily extensible structure (new languages can be added)

Requirements

Android App

Android 8.0 (API 26) and above
BLE-capable device
Bluetooth, Location, Notification permissions

Server

PHP 8.1+
MySQL 8.0+ / MariaDB 10.6+
Apache or Nginx

Installation

Phase 1: Server (PHP Backend)

1.1 Clone the repository

git clone https://github.com/burakyalti/realtime-heart-rate-monitor.git
cd realtime-heart-rate-monitor

1.2 Copy server files to your web server

cp -r server/ /var/www/html/hr/

1.3 Create the database

mysql -u root -p < server/schema.sql

This command automatically creates the heart_rate_db database and 3 tables:

Table	Description
`heart_rate_logs`	Raw heart rate data (BPM, RR intervals, battery, sensor contact)
`heart_rate_alerts`	Threshold violation alarms (low/high/no signal)
`heart_rate_stats`	Hourly statistics (min, max, average)

1.4 Set up environment variables

cd /var/www/html/hr/
cp .env.example .env
chmod 600 .env
nano .env

Fill in the .env file with your information:

HR_DB_HOST=localhost
HR_DB_NAME=heart_rate_db
HR_DB_USER=your_db_user
HR_DB_PASS=your_db_password
HR_API_KEY=your-secret-api-key
HR_ALLOWED_DEVICES=XX:XX:XX:XX:XX:XX

Variable	Description
`HR_DB_HOST`	MySQL server address
`HR_DB_NAME`	Database name
`HR_DB_USER`	Database user
`HR_DB_PASS`	Database password
`HR_API_KEY`	Security key the Android app uses when sending data
`HR_ALLOWED_DEVICES`	Allowed BLE device MAC addresses (multiple: comma-separated)

1.5 Verify installation

Open in browser: https://your-server.com/hr/live.php

If the dashboard loads, server setup is complete. You'll see a "No data" message since there's no data yet.

Phase 2: Android App

2.1 Install the App

Install from APK:

Download the hr.apk file to your Android device
Allow "Install from unknown sources"
Complete the installation

Or build from source:

cd realtime-heart-rate-monitor
./gradlew assembleDebug
# APK: app/build/outputs/apk/debug/app-debug.apk

2.2 App Settings

Open the app, go to Settings (gear icon in top right)
In Server Settings section:
- API URL: https://your-server.com/hr/api/log.php
- API Key: The HR_API_KEY value you set in .env file in Phase 1
Select Server mode in Device Mode section
Return to main screen and connect your BLE sensor

Once connected, data will automatically be sent to the server. You can monitor live at live.php.

API Endpoints

Send Data (Android App → Server)

POST /api/log.php
Headers:
  Content-Type: application/json
  X-API-Key: {API_KEY}

Body:
{
  "device_mac": "XX:XX:XX:XX:XX:XX",
  "heart_rate": 72,
  "rr_intervals": [850, 862, 845],
  "battery_level": 85,
  "sensor_contact": true,
  "timestamp": 1699876543210
}

Data Reading Endpoints

Endpoint	Method	Description
`/api/latest.php`	GET	Latest heart rate data (BPM, battery, time)
`/api/chart-data.php?seconds=60`	GET	Chart data (last N seconds)
`/api/minute-summary.php?hours=1`	GET	Per-minute average/min/max (last N hours)
`/api/sse.php`	GET	Server-Sent Events (real-time data stream)
`/api/history.php`	GET	Hourly statistics history
`/api/alerts.php`	GET	Alert history

Live Dashboard

GET /live.php

Live dashboard accessible from web browser or Android Client mode:

Real-time BPM indicator (instant updates via SSE)
Heart rate and ECG chart (30sec - 60min range)
Range slider for time interval selection
Per-minute average chart (1h - 24h)
Battery level and signal status

Technical Details

Language: Kotlin
UI Framework: Jetpack Compose
Minimum SDK: 26 (Android 8.0)
Target SDK: 35 (Android 15)
Architecture: Single Activity + Compose Navigation
BLE: Android Bluetooth LE API
HTTP Client: Ktor

Project Structure

Android App

app/src/main/java/net/hrapp/hr/
├── MainActivity.kt           # Main activity and state management
├── ble/
│   └── BleManager.kt         # BLE connection management
├── data/
│   └── PreferencesManager.kt # SharedPreferences management
├── network/
│   └── ApiClient.kt          # HTTP requests
├── service/
│   ├── HeartMonitorService.kt    # Server mode foreground service
│   └── ClientMonitorService.kt   # Client mode foreground service
└── ui/
    ├── components/           # Reusable UI components
    ├── screens/              # Screen composables
    └── theme/                # Color and theme definitions

PHP Server

server/
├── config.php                # Configuration (.env reading, DB connection)
├── live.php                  # Live dashboard (SSE, Chart.js, ECG)
├── schema.sql                # Database schema (3 tables)
├── .env.example              # Environment variables template
├── .gitignore
└── api/
    ├── log.php               # Data logging (POST - Android app sends)
    ├── latest.php            # Latest heart rate data (GET)
    ├── chart-data.php        # Chart data (GET, ?seconds=N)
    ├── minute-summary.php    # Per-minute average (GET, ?hours=N)
    ├── sse.php               # Server-Sent Events (real-time stream)
    ├── history.php           # Hourly statistics (GET)
    └── alerts.php            # Alert history (GET)

License

This project is licensed under the MIT License.

Contact

For questions or feedback, please use GitHub Issues.

Disclaimer

This application is developed for personal use only and is not a medical device.

The ECG chart in the application is a representative visualization derived from heart rate (BPM) data. It does not perform actual electrocardiogram (ECG/EKG) measurements.

The displayed data should not be used as a reference for diagnosis, treatment, or any health-related decisions.

Always consult a healthcare professional for health concerns.

The developers accept no responsibility for any direct or indirect consequences arising from the use of this application.

Name		Name	Last commit message	Last commit date
Latest commit History 8 Commits
.github/workflows		.github/workflows
app		app
gradle		gradle
screenshots		screenshots
server		server
.gitignore		.gitignore
README.md		README.md
README_TR.md		README_TR.md
build.gradle.kts		build.gradle.kts
gradle.properties		gradle.properties
gradlew		gradlew
gradlew.bat		gradlew.bat
hr.apk		hr.apk
settings.gradle.kts		settings.gradle.kts

Folders and files

Latest commit

History

Repository files navigation

Real-Time Heart Rate Monitor

Screenshots

Live Heart Rate Screen

Charts and Daily Statistics

Hourly Charts

Hourly Summary Table

All Records

Device Mode Settings

Alert and Service Settings

API Settings

Features

BLE Connection

Data Analysis

Server Synchronization

Alerts

Background Service

Multi-Language Support

Requirements

Android App

Server

Installation

Phase 1: Server (PHP Backend)

1.1 Clone the repository

1.2 Copy server files to your web server

1.3 Create the database

1.4 Set up environment variables

1.5 Verify installation

Phase 2: Android App

2.1 Install the App

2.2 App Settings

API Endpoints

Send Data (Android App → Server)

Data Reading Endpoints

Live Dashboard

Technical Details

Project Structure

Android App

PHP Server

License

Contact

Disclaimer

About

Resources

Uh oh!

Stars

Watchers

Forks

Releases

Packages 0

Uh oh!

Contributors

Uh oh!

Languages

Packages