Somtimes, we need to measure the level of water in a recipient, or if you want to see the level of water in a tank, it is a requirement to measure the levels of water that it has; so in this section, we will explain how to do this.

The sensor is Normally Open. When the water is over the limit, the contact opens, and it sends a signal to the Arduino board. We use pin number 2, which is a digital input:

We declare the variables and const in the program:

const int buttonPin = 2;     // the number of the input sensor pin 
const int ledPin =  13;      // the number of the LED pin 

We also define the states of the digital signals:

// variables will change: 
intbuttonState = 0;         // variable for reading the pushbutton status 

We configure the signals of the program, inputs, and outputs:

void setup() { 
  // initialize the LED pin as an output: 
pinMode(ledPin, OUTPUT); 
  // initialize the pushbutton pin as an input: 
pinMode(buttonPin, INPUT); 
Serial.begin(9600); 
} 

We read the state of the digital input:

void loop() { 
  // read the state of the pushbutton value: 
buttonState = digitalRead(buttonPin); 

We make the comparisons for the sensor:

if (buttonState == HIGH) { 
Serial.println(buttonState); 
Serial.println("The recipient is fulled"); 
digitalWrite(ledPin, HIGH); 
delay(1000); 
  } 

If the sensor detects a LOW level, the recipient is empty:

else { 
digitalWrite(ledPin, LOW); 
Serial.println(buttonState); 
Serial.println("The recipient is empty"); 
delay(1000); 
  } 
} 

The following screenshot shows the result when the recipient is empty:

The water is over the limit: