This project will help you to maintain the water level in water tank. We used sonar to detect the water level. Connect Arduino as per below diagram

Below is a sample code for this project

 

#include <LCD.h>
#include <LiquidCrystal_SR.h>
#include <LiquidCrystal.h>
LiquidCrystal_SR lcd(12, 13, 8);
// defines pins numbers
const int trigPin = 9;
const int echoPin = 10;
const int left=2;
const int right=3;
const int fwd=4;
const int back=5;
const int motorpin=6;

// defines variables
long duration;
int distance;
int upperlevel=50,lowerlevel=150;
bool motorstat=false;

bool leftpin=true,rightpin=true,backpin=true,fwdpin=true;
void setup() {
// put your setup code here, to run once:
lcd.begin(16, 2); // set up the LCD’s number of columns and rows:
lcd.clear(); // clear the screen
pinMode(left, INPUT);
pinMode(right, INPUT);
pinMode(fwd, INPUT);
pinMode(back, INPUT);
pinMode(motorpin, OUTPUT);

pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
Serial.begin(9600);
digitalWrite(motorpin, LOW);
}

void loop() {
// put your main code here, to run repeatedly:
lcd.setCursor(0, 0);
lcd.print(“U:”); // print Upper level
lcd.print(upperlevel);
lcd.print(“::L:”); // print Lower Level
lcd.print(lowerlevel);
lcd.print(“:::”);

leftpin = digitalRead(left);
rightpin = digitalRead(right);
fwdpin = digitalRead(fwd);
backpin = digitalRead(back);
if(leftpin==false){
Serial.println(“left press”);
lowerlevel=lowerlevel-1;
if(lowerlevel<0)
lowerlevel=0;
delay(2000);
}
if(rightpin==false){
Serial.println(“right press”);
lowerlevel=lowerlevel+1;
delay(500);
}
if(fwdpin==false){
Serial.println(“fwd press”);
upperlevel=upperlevel+1;
delay(500);
}
if(backpin==false){
Serial.println(“back press”);
upperlevel=upperlevel-1;
if(upperlevel<0)
upperlevel=0;
delay(500);
}

digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);

duration = pulseIn(echoPin, HIGH);
distance= duration*0.034/2;

Serial.print(“Cur: “);
Serial.println(distance);
lcd.setCursor(0, 1);
lcd.print(“Cur:”); //Print current water level
lcd.print(distance);lcd.print(“:Motor:”);
if(motorstat==true)
lcd.print(“ON:”);
else
lcd.print(“OFF:”);

if(distance>lowerlevel && motorstat==false){
motorstat=true;
digitalWrite(motorpin, HIGH);
}
if(distance<upperlevel && motorstat==true){
motorstat=false;
digitalWrite(motorpin, LOW);
}

}

 

Below project will help you to understand the level calculation using sonar

Arduino Distance Calculation Using Sonar