Ultrasonic Object Detection and Distance Measurement System using HC-SR04, LPC1768, and 16x2 LCD

A real-time ultrasonic object detection system developed in Embedded C for the LPC1768 microcontroller using Keil μVision. It uses the HC-SR04 sensor to measure distance, displays the result on a 16x2 LCD, and activates an LED when an object is detected within a 30 cm threshold—ideal for basic proximity alert applications in embedded systems.

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Components

• LPC1768 Cortex-M3 Development Board (with LCD and LEDs)
• HC-SR04 Ultrasonic Sensor
• Jumper wires
• USB Cable

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Pin Configuration

Component	LPC1768 Pin
Trigger	P0.15
Echo	P0.16
LED	P0.8
LCD RS	P0.27
LCD EN	P0.28
LCD D4-D7	P0.23-P0.26

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Setup

1. Connect components as per pin configuration
2. Power system with 3.3V supply
3. Connect LCD contrast potentiometer
4. Ensure proper ground connections

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Usage

1. System continuously displays distance on LCD
2. LED illuminates when object is within 30cm
3. Measurement updates every 300ms

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Dependencies

• CMSIS library for LPC1768
• Standard C library for printf functions

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Notes

• Adjust distance threshold by modifying distance < 30 in main loop
• Calibrate speed of sound constant (343 m/s) for different environments
• Ensure sensor has clear line-of-sight for accurate measurements