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🎯 Portfolio-Grade Embedded Systems Project

Comprehensive distance measurement system demonstrating ultrasonic sensing, real-time signal processing, hardware–software integration, and multi-platform interfacing using Arduino UNO.

⭐ Perfect for academics, portfolio demonstrations, and embedded systems fundamentals

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📋 Table of Contents

• 🚀 Project Overview
• ✨ Key Features
• 🎬 Demo
• 📦 Hardware Requirements
• 🔌 Circuit Connections
• 🧠 Working Principle
• 💻 Software Setup
• 🚀 Quick Start Guide
• 🔧 Customization
• 🎓 Learning Outcomes
• 🌟 Use Cases
• 🐛 Troubleshooting
• 📊 Technical Specifications
• 🤝 Contributing
• 📞 Connect

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🚀 Project Overview

Real-Time Sensing 10 Hz sampling rate with HC-SR04

Multi-Platform Arduino + Python integration

Production Ready Clean, modular, documented

This project implements a comprehensive distance measurement system featuring:

• 🎯 Real-time distance calculation with visual LED feedback
• 🖥️ Dual Python interface support (GUI + Audio Alert System)
• 🔔 Threshold-based object detection and triggering
• 📡 Serial communication protocol for cross-platform integration

Designed to be modular, deterministic, and interview-ready — optimized for academic excellence and portfolio demonstrations.

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✨ Key Features

Feature	Description
⚡ Hardware-Software Integration	Seamless Arduino-Python communication via UART
🎨 Multiple Output Modes	Compatible with GUI and audio alert systems simultaneously
🔄 Real-time Processing	10 Hz sampling rate with precise distance calculation
💡 Visual Feedback	LED indicator for proximity alerts (10-40 cm range)
🧩 Modular Design	Easy to extend and customize for specific applications
📝 Professional Code	Clean, well-documented, interview-ready implementation

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🎬 Demo

System Architecture

┌─────────────────┐         ┌──────────────────┐         ┌─────────────────┐
│   HC-SR04       │  GPIO   │   Arduino UNO    │  UART   │  Python Host    │
 │  Ultrasonic     │ ──────> │  Microcontroller │ ──────> │   Application   │ 
│    Sensor       │         │                  │         │   (GUI/Audio)   │
└─────────────────┘         └──────────────────┘         └─────────────────┘
│
▼
┌──────────────┐
│  LED Visual  │
│   Feedback   │
└──────────────┘

Expected Output

Serial Monitor (9600 baud):

25.3
23.7
21.4
PLAY_AUDIO  ← Trigger sent when object in range
20.1
18.9

LED Behavior:

• 🟢 OFF: Distance > 40 cm or < 10 cm
• 🔴 ON: Distance between 10-40 cm (object detected)

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📦 Hardware Requirements

Components List

Component	Quantity	Purpose	Specifications
Arduino UNO	1	Microcontroller	ATmega328P, 5V logic
🔊 HC-SR04 Sensor	1	Distance measurement	2-400 cm range, 40 kHz
💡 LED (any color)	1	Visual indicator	5mm, 20mA forward current
🔌 220Ω Resistor	1	LED current limiting	1/4W, ±5% tolerance
🔗 Jumper Wires	6+	Connections	Male-to-male
🔌 USB Type-B Cable	1	Programming & power	Data-capable cable

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🔌 Circuit Connections

Pin Mapping

HC-SR04 → Arduino UNO
HC-SR04 Pin	Arduino Pin	Description
VCC	5V	Power supply (+)
GND	GND	Ground reference
TRIG	D9	Trigger pulse input
ECHO	D10	Echo pulse output

LED Circuit
LED Terminal	Connection
Anode (+) [Long leg]	D3 (via 220Ω resistor)
Cathode (–) [Short leg]	GND

Circuit Diagram

        ┌─────────────────────────────┐
        │      Arduino UNO            │
        │                             │
                      │  5V  ──────────────────────>│ VCC (HC-SR04)
                      │  GND ──────────────────────>│ GND (HC-SR04)
             │  D9  ──────────────────────>│ TRIG
             │  D10 <──────────────────────│ ECHO
        │                             │
            │  D3  ───[220Ω]───>│+LED−│──>│ GND
        │                             │
                 │  USB <──────────────────────│ Computer
        └─────────────────────────────┘

📌 Note: For visual circuit diagram, see circuit_diagram.png in repository

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🧠 Working Principle

Distance Measurement Algorithm

Step-by-Step Process: Trigger Phase Arduino sends 10µs HIGH pulse to TRIG pin Ultrasonic Emission HC-SR04 emits 8 pulses of 40 kHz ultrasonic waves Echo Detection Waves reflect from object and return to sensor Time Measurement ECHO pin stays HIGH for duration proportional to distance Distance Calculation Distance (cm) = (Duration × 0.0343) / 2 Threshold Detection LED activates when distance is 10-40 cm Serial Output Distance values transmitted via UART (9600 baud)

Mathematical Foundation: Speed of Sound in Air: 343 m/s = 0.0343 cm/µs Time-of-Flight: Total Time = Distance to Object × 2 / Speed Distance Formula: Distance = (Time × Speed) / 2 Distance = (Duration × 0.0343) / 2 Why divide by 2? Ultrasonic wave travels to object and back Measured time includes round-trip travel Measurement Range: Minimum: 2 cm (sensor limitation) Maximum: 400 cm (signal attenuation) Accuracy: ±3 mm (optimal conditions)

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💻 Software Setup

Arduino Development Environment

Arduino IDE Version 1.8.x or 2.x

Language C/C++ (Arduino Core)

Communication UART @ 9600 baud

Python Environment (Optional)

Python 3.8+

pyserial

pygame

Terminal

Install Python dependencies:

pip install pyserial pygame

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🚀 Quick Start Guide

📁 Step 1: Clone Repository

git clone https://github.com/aryan-r03/ultrasonic-distance-arduino.git
cd ultrasonic-distance-arduino

⚡ Step 2: Upload Arduino Code

1. Open Arduino IDE
2. Load arduino_sketch_simple.ino
3. Connect Arduino UNO via USB
4. Configure IDE:
   • Tools → Board → Arduino UNO
   • Tools → Port → Select correct port
     • Windows: COM3, COM4, etc.
     • macOS: /dev/cu.usbmodem*
     • Linux: /dev/ttyUSB0, /dev/ttyACM0
5. Click Upload (→ button)
6. Wait for "Done uploading" message

🔍 Step 3: Verify Operation

Open Serial Monitor: Tools → Serial Monitor (or Ctrl+Shift+M)

Set to: 9600 baud

Expected Output:

25.3
23.7
21.4
PLAY_AUDIO    ← Trigger when object at 10-40 cm
20.1
18.9

Physical Testing:

1. Move hand/object in front of sensor
2. LED should illuminate when object is 10-40 cm away
3. "PLAY_AUDIO" appears in serial when LED is ON

🐍 Step 4: Run Python Interfaces (Optional)

Option A: GUI Display python Distance_GUI.py Features: 📊 Real-time distance visualization 🎨 Color-coded display: 🟢 Green: >50 cm (Safe) 🟡 Yellow: 20-50 cm (Caution) 🔴 Red: <20 cm (Alert) 🔊 Text-to-speech announcements

Option B: Audio Alert System python Distance_custom_audio.py Features: 🎵 Listens for "PLAY_AUDIO" trigger 🔊 Plays sequential audio warnings ⏱️ 5-second cooldown between alerts 📁 Custom audio file support

⚠️ Important: Update serial port in Python files:

# macOS
SERIAL_PORT = "/dev/cu.usbmodem101"

# Linux
SERIAL_PORT = "/dev/ttyUSB0"

# Windows
SERIAL_PORT = "COM3"

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🔧 Customization

Modify Detection Range

Edit in arduino_sketch_simple.ino:

#define MIN_DISTANCE 10  // Minimum trigger distance (cm)
#define MAX_DISTANCE 40  // Maximum trigger distance (cm)

// Example: Detect objects 20-60 cm away
#define MIN_DISTANCE 20
#define MAX_DISTANCE 60

Adjust Sampling Rate

delay(100);  // Current: 10 Hz (100ms interval)

// Faster sampling (20 Hz)
delay(50);

// Slower sampling (5 Hz)
delay(200);

Change Debounce Period

#define DEBOUNCE_DELAY 1500  // Milliseconds between triggers

// Reduce trigger frequency (3 seconds)
#define DEBOUNCE_DELAY 3000

// Increase trigger frequency (1 second)
#define DEBOUNCE_DELAY 1000

Modify LED Behavior

// Current: LED ON when object in range
digitalWrite(LED_PIN, HIGH);

// Inverse: LED OFF when object in range
digitalWrite(LED_PIN, LOW);

// Blinking LED
digitalWrite(LED_PIN, millis() % 500 < 250 ? HIGH : LOW);

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🎓 Learning Outcomes

Embedded Systems Time-of-flight measurement GPIO & digital signals PWM concepts Real-time processing

Software Engineering Serial protocols (UART) Hardware-software integration Multi-platform design State machine implementation

Cross-Platform Dev Python serial communication GUI development Audio processing Real-time data handling

Professional Skills Clean, maintainable code Comprehensive documentation Modular architecture Version control practices

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🌟 Use Cases

🎓 Academic & Learning 📚 Embedded systems labs 🔬 Microcontroller programming 🧪 Sensor integration demos 📊 Data acquisition projects

🚀 Practical Applications 🤖 Robotics: Navigation systems 🚗 Automotive: Parking assistance 🏠 Smart Home: Automated doors 🏭 Industrial: Presence detection 📡 IoT: Distance-based triggers

💼 Portfolio Enhancement ✅ Hardware-software integration ✅ Multi-language proficiency ✅ Professional documentation ✅ Real-world problem solving ✅ Interview-ready project

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🐛 Troubleshooting

❌ No Serial Output

Solutions:

• ✅ Check USB connection (use data-capable cable, not charge-only)
• ✅ Verify correct COM port selected in Arduino IDE
• ✅ Confirm baud rate is 9600 in Serial Monitor
• ✅ Check Arduino board selection: Tools → Board → Arduino UNO
• ✅ Try different USB port on computer
• ✅ Restart Arduino IDE

📏 Incorrect Distance Readings

Solutions:

• ✅ Verify HC-SR04 wiring:
  • VCC → 5V
  • GND → GND
  • TRIG → D9
  • ECHO → D10
• ✅ Ensure sensor has clear line of sight (no obstructions)
• ✅ Check 5V power supply is stable (measure with multimeter: 4.8-5.2V)
• ✅ Avoid angled surfaces (use flat, perpendicular objects)
• ✅ Don't use sound-absorbing materials (foam, fabric)
• ✅ Test at 20-50 cm distance first (optimal range)

💡 LED Not Working

Solutions:

• ✅ Check LED polarity:
  • Long leg (anode) → 220Ω resistor → D3
  • Short leg (cathode) → GND
• ✅ Verify 220Ω resistor is in series (not parallel)
• ✅ Confirm LED is not burnt out (test with battery)
• ✅ Check D3 pin connection
• ✅ Test with multimeter: LED should drop ~2V when ON

🐍 Python Script Connection Errors

Solutions:

• ✅ Close Arduino Serial Monitor before running Python (port conflict)
• ✅ Update SERIAL_PORT variable with correct port:

  # Find your port:
  # Windows: Device Manager → Ports (COM & LPT)
  # macOS: ls /dev/cu.*
  # Linux: ls /dev/ttyUSB* /dev/ttyACM*

• ✅ Check port permissions (Linux/macOS):

  sudo chmod 666 /dev/ttyUSB0
  # or add user to dialout group:
  sudo usermod -a -G dialout $USER

• ✅ Install required libraries:

  pip install pyserial pygame

• ✅ Verify Python version: python --version (3.8+)

⚠️ Unstable/Fluctuating Readings

Solutions:

• ✅ Add smoothing/filtering in code:

  // Moving average of last 5 readings
  float readings[5];
  float average = 0;
  for(int i = 0; i < 5; i++) {
    readings[i] = distance;
    average += readings[i];
  }
  average /= 5;

• ✅ Increase DEBOUNCE_DELAY to reduce noise
• ✅ Shield sensor from electromagnetic interference
• ✅ Use shielded cables for long wire runs
• ✅ Add decoupling capacitor (0.1µF) across VCC-GND

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📊 Technical Specifications

System Performance

Parameter	Value	Notes
Operating Voltage	5V DC	Regulated from USB (4.8-5.2V)
Current Consumption	~30mA	Arduino (15mA) + HC-SR04 (15mA)
Measurement Range	2 cm - 400 cm	Effective: 10-300 cm
Accuracy	±3 mm	Under optimal conditions
Resolution	1 cm	Limited by calculation
Measurement Angle	15° cone	30° total beam width
Ultrasonic Frequency	40 kHz	8 pulses per measurement
Sampling Rate	10 Hz	100ms measurement cycle
Serial Baud Rate	9600	UART, 8N1 configuration
Response Time	<100 ms	Total system latency

Environmental Conditions

Parameter	Range
Operating Temperature	-10°C to 60°C
Storage Temperature	-20°C to 70°C
Humidity	10% - 90% RH (non-condensing)

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📂 Project Structure

ultrasonic-distance-arduino/
│
├── 📄 arduino_sketch_simple.ino          # Main Arduino sketch (RECOMMENDED)
├── 📄 arduino_sketch_compatible.ino      # Advanced mode-selectable version
│
├── 🐍 Distance_GUI.py                    # Real-time GUI display interface
├── 🐍 Distance_custom_audio.py           # Audio alert system
│
├── 🖼️ circuit_diagram.png                # Wiring diagram
├── 📖 README.md                          # This file
├── 📜 LICENSE                            # MIT License
│
└── 📁 audio_files/                       # Audio alerts (user-provided)
    ├── 🔊 audio_1.mp3
    ├── 🔊 audio_2.mp3
    └── 🔊 audio_3.mp3

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🔄 Version History

Version Timeline

Version	Date	Changes
v2.0 (Current)	Jan 2025	✅ Added dual Python interface support ✅ Implemented mode-selectable operation ✅ Enhanced serial protocol ✅ Improved documentation ✅ Added troubleshooting guide
v1.5	Dec 2024	✅ Added debounce mechanism ✅ Improved stability ✅ Added configuration options
v1.0	Nov 2024	✅ Basic distance measurement ✅ LED indicator ✅ Serial output

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🤝 Contributing

Contributions are welcome! Help improve this project:

1. 🍴 Fork the repository
2. 🌿 Create a feature branch

   git checkout -b feature/enhancement

3. ✍️ Commit your changes

   git commit -m 'Add amazing enhancement'

4. 📤 Push to the branch

   git push origin feature/enhancement

5. 🔀 Open a Pull Request

Contribution Guidelines

• 📝 Follow existing code style
• ✅ Test thoroughly before submitting
• 📖 Update documentation for new features
• 🐛 Include issue number in PR description
• 💬 Provide clear commit messages

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📄 License

This project is licensed under the MIT License

See LICENSE file for complete details

MIT License - Free to use, modify, and distribute
Attribution appreciated but not required

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👨‍💻 Author

🎓 Computer Applications in AI & ML
Building at the intersection of hardware and software

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🙏 Acknowledgments

Special thanks to:

• 🌐 Arduino Community for comprehensive documentation
• 📘 HC-SR04 Datasheet Authors for technical specifications
• 🐍 PySerial & Pygame Contributors for Python libraries
• 👥 Open Source Community for continuous inspiration

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📞 Support & Contact

Need Help?

Open an Issue GitHub Issues

Email

Documentation See README & Code Comments

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🌟 Show Your Support

If this project helped you, please consider:

⭐ Star this repository if you found it helpful!

🍴 Fork it to customize for your projects!

📢 Share it with others learning embedded systems!

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💡 "Hardware is hard. Software is soft. Integration is magic."

Made with Arduino by Aryan Ranjan

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**© 2025 Aryan Ranjan | Open Source | IoT & Embedded Systems **