📡 Ultrasonic Proximity Alert System

A servo-mounted ultrasonic scanner that detects nearby objects, displays real-time distance data on an LCD, and triggers an audible alert when an object enters a defined proximity range.

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🔎 Overview

The Ultrasonic Proximity Alert System uses an ultrasonic range sensor mounted on a rotating servo to continuously scan the environment.
When an object is detected within a configurable threshold (e.g., 0–40 cm), the system:

• Stops the servo to “lock” onto the object
• Displays OBSTACLE DETECTED and the measured distance on a 16×2 I2C LCD
• Activates a buzzer alert
• Returns to scanning mode once the object is no longer detected
• Can be toggled ON/OFF using an external switch

This project demonstrates embedded systems concepts such as real-time sensor measurement, PWM control, hardware interrupts/polling, and state-machine-based logic.

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🎯 Project Goals

• Implement real-time distance measurement using an ultrasonic sensor
• Design a scanning mechanism using a servo motor
• Apply state-machine logic for system behavior
• Provide immediate visual and audible feedback
• Build a reliable, low-cost obstacle detection system

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🛠️ Hardware Components

• ESP32 DevKit (WROVER)
• HC-SR04 ultrasonic sensor
• SG90 servo motor
• 16×2 I2C LCD display
• Active piezo buzzer
• Mini slide switch
• Breadboard + jumper wires

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🧱 Dependencies & Failure Impact

Hard Dependencies

These components are required for core system functionality:

• Ultrasonic sensor – primary distance measurement
• Servo motor – enables environmental scanning
• ESP32 PWM and GPIO – required for real-time control and signal handling

Soft Dependencies

These components enhance usability but are not required for detection:

• LCD display – visualization of system state and distance measurements
  (System remains functional without display output)

Failure Impact

• Ultrasonic sensor failure → No obstacle detection possible
• LCD failure → Detection and alerting continue without visual feedback

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🏗️ High-Level Architecture

Inputs

• Ultrasonic echo signal
• System ON/OFF switch

Outputs

• Servo motor (PWM control)
• LCD display (I2C)
• Buzzer alert (GPIO)

Controller

• ESP32 DevKit (WROVER)

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🔌 Pin Layout

Adjust according to your wiring — example layout:

Component	Pin	Description
Ultrasonic TRIG	GPIO 14	Trigger pulse
Ultrasonic ECHO	GPIO 12	Echo measurement
Servo Signal	GPIO 13	PWM control
Buzzer	GPIO 15	Alert output
LCD SDA	GPIO 4	I2C data
LCD SCL	GPIO 2	I2C clock
Switch	5V	System ON/OFF input

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💻 How the Code Works

1. Initialization

• Sets up GPIO pins, servo PWM, LCD, and switch input.
• Clears the LCD and sets up initial states.

2. System ON/OFF Handling

• If the switch is OFF → LCD shuts down, servo stops, buzzer stays OFF.
• When switched back ON, LCD re-initializes properly and scanning starts.

3. Scanning Mode

• Servo rotates from left → right, then right → left.
• At each angle step:
  • Ultrasonic sensor measures distance.
  • LCD displays “SCANNING” + distance.

4. Object Detection

• If distance ≤ threshold (e.g., 40 cm):
  • Servo freezes at its current angle.
  • LCD shows OBSTACLE DETECTED and range.
  • Buzzer beeps.
  • System waits until object is gone.

5. Resume Scanning

• After the object is out of range:
  • LCD shows Obstacle out of view.
  • Buzzer turns off.
  • System returns to scanning mode.