Ultrasonic Water Level Indicator Using 8051 Microcontroller

Introduction

Monitoring the water level in tanks or reservoirs is essential to prevent overflow and manage water usage efficiently. An ultrasonic water level indicator provides a non-contact method for measuring the water level using ultrasonic waves. This project demonstrates how to design an ultrasonic water level indicator using the 8051 microcontroller and an ultrasonic sensor.

Components Required

• 8051 Microcontroller (e.g., AT89S52)

• Ultrasonic Sensor (e.g., HC-SR04)

• 16x2 LCD Display (for displaying water level)

• Resistors (10kΩ, 1kΩ)

• Capacitors (33pF, 100μF)

• Crystal Oscillator (11.0592 MHz)

• Breadboard and Connecting Wires

• Power Supply (5V for the 8051 and sensor)

Circuit Diagram

The ultrasonic sensor is used to measure the distance to the water surface. The 8051 microcontroller processes this data and displays the water level on the LCD.

+5V ----- +5V

          |

          |

       HC-SR04

        +---+

    VCC |VCC| 

    GND |GND|

  TRIG  |TRIG|------- P3.2 (8051)

  ECHO  |ECHO|------- P3.3 (8051)

         +---+

LCD Display

    VSS to Ground

    VCC to +5V

    VEE to Potentiometer (for contrast control)

    RS  to P2.0 (8051)

    RW  to Ground

    E   to P2.1 (8051)

    D4  to P2.2 (8051)

    D5  to P2.3 (8051)

    D6  to P2.4 (8051)

    D7  to P2.5 (8051)

Pin Connections

• Ultrasonic Sensor (HC-SR04):

• VCC to +5V

• GND to Ground

• TRIG to P3.2 of the 8051

• ECHO to P3.3 of the 8051

• LCD Display:

• VSS to Ground

• VCC to +5V

• VEE to the potentiometer for contrast control

• RS to P2.0 of the 8051

• RW to Ground

• E to P2.1 of the 8051

• D4 to P2.2 of the 8051

• D5 to P2.3 of the 8051

• D6 to P2.4 of the 8051

• D7 to P2.5 of the 8051

Software Implementation

The code is written in C using Keil uVision IDE. It involves triggering the ultrasonic sensor, measuring the echo time, calculating the distance, and displaying the water level on the LCD.

#include <reg51.h>

#include <lcd.h> // Include a custom LCD library

sbit TRIG = P3^2; // Trigger pin

sbit ECHO = P3^3; // Echo pin

void delay(unsigned int time) {

    unsigned int i, j;

    for(i = 0; i < time; i++)

        for(j = 0; j < 1275; j++);

}

void sendTriggerPulse() {

    TRIG = 1;

    delay(1); // 10us delay

    TRIG = 0;

}

unsigned int getEchoTime() {

    unsigned int time = 0;

    while (!ECHO); // Wait for echo start

    while (ECHO) { // Measure echo pulse duration

        time++;

        delay(1);

    }

    return time;

}

void main() {

    unsigned int echoTime;

    unsigned int distance;

    char distanceStr[16];

    lcd_init(); // Initialize the LCD

    TRIG = 0; // Set Trigger pin low initially

    while (1) {

        sendTriggerPulse(); // Send trigger pulse

        echoTime = getEchoTime(); // Measure echo time

        distance = echoTime / 58; // Calculate distance in cm

        sprintf(distanceStr, "Distance: %d cm", distance);

        lcd_clear();

        lcd_print(distanceStr); // Display distance on LCD

        delay(1000); // Delay for stability

    }

}

Explanation

1. Initialization:

2. LCD Initialization: The lcd_init() function configures the LCD for display.

3. Trigger Pin Initialization: The TRIG pin is set low initially.

4. Sending Trigger Pulse:

5. The sendTriggerPulse() function sends a 10μs pulse to the TRIG pin of the ultrasonic sensor to initiate measurement.

6. Measuring Echo Time:

7. The getEchoTime() function measures the duration of the echo pulse received from the ECHO pin. This duration corresponds to the time taken by the ultrasonic wave to travel to the water surface and back.

8. Calculating Distance:

9. The distance is calculated using the formula distance = echoTime / 58, which converts the time duration to distance in centimeters.

10. Displaying Distance:

11. The distance is converted to a string and displayed on the LCD using the lcd_print() function.

12. Delay Function:

13. The delay function introduces a small delay between each measurement for stability.

Conclusion

This project demonstrates the use of the 8051 microcontroller to create an ultrasonic water level indicator. By integrating an ultrasonic sensor and an LCD, the system can measure and display the water level accurately. This project is a great way to learn about sensor interfacing, distance measurement, and using microcontrollers for real-time monitoring applications.

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