We will use an ultrasonic sensor to measure the water level in the container. Once the water level falls below a certain threshold, we will send an email using the Blynk App. Also we will send level of our water container to the Blynk App continuously so it can be looked at any time. For the automatic irrigation system, whenever the moisture value of the soil is lower than a certain value, the pump would turn on and water the crop. For this, an L293D module was used as before.

I will not go to deeply into each component and wiring as it is almost similar to #03: Setting up the AgroBot

Whenever the distance from the Ultrasonic sensor was less than 3, we sent an email warning to refill the tank.

//sending email when water level falls below 3
if (cm < 3)
{
Blynk.email("Water level alert", "Fill water in the container");
}

Whenever the moisture level was less than 60(chosen randomly here), we will water the crop using the pump.

//for watering the crop below 60 moisture level
if(moisture_value < 60)
{
   digitalWrite(motorA1,HIGH);
digitalWrite(motorA2,LOW);
   delay(100);
   digitalWrite(motorA1,LOW);
digitalWrite(motorA2,LOW);

}

To send data to the Blynk App, I used the below snippet. In the App, I set PIN as V0 and widget level H

Blynk.virtualWrite(V0, water_level());

Code:

//Remote Agriculture Solution
//Irrigation system
/*          Using Arduino Nano 33 IOT to make a water irrigation system
  Dev: Aaryan Arora
  For Design For A Cause 2021
*/
//libraries
#define BLYNK_PRINT SerialUSB
#include <SPI.h>
#include <WiFiNINA.h>
#include <BlynkSimpleWiFiNINA.h>
#include <EduIntro.h>
/* Used this library for getting temperature reading from DHT 11
  Can be downloaded from here or arduino library manager
  https://github.com/arduino/EduIntro
*/
#define TRIGGER_PIN1  8  // Arduino pin tied to trigger pin on the ultrasonic sensor.
#define ECHO_PIN1     12  // Arduino pin tied to echo pin on the ultrasonic sensor.

//define motor pins for the water pump
const int motorA1 = 2;    //motor A positive (+) pin to pin 6 (PWM) (from L293D module!)
const int motorA2 = 3;        //motor A negative (-) pin to pin 9 (PWM)

DHT11 dht11(D7);  // creating the object sensor on pin 'D7'
int water_level(); //to measure level of water in container


//Use your authorization token after creating new project in Blynk App
char auth[] = "";


// Your WiFi credentials.
// Set password to "" for open networks.
char ssid[] = "";
char pass[] = "";


//constants
int LDRpin = A0; // select the input pin for LDR
int LDRvalue = 0; // variable to store the value coming from the LDR
int lux = 0;         //to store the intensity of light in lux
long duration, cm;
int soil_pin = A2; //soil sensor pin
int moisture_value ; //storing result from soil sensor


BlynkTimer timer;
// This function sends Arduino's up time every second to Virtual Pin (5).
// In the app, Widget's reading frequency should be set to PUSH. This means
// that you define how often to send data to Blynk App.


void myTimerEvent()
{
  //starting the DHT 11 sensor
  dht11.update();


  //Getting the LDR analog value
  LDRvalue = analogRead(LDRpin);
  //Using the formula for conversion from analog value to lux
  lux = (512000 / LDRvalue) - 500;


  //calculating moisture percentage using analog value of the sensor
  moisture_value = analogRead(soil_pin);
  //converting to percentage
  moisture_value = (moisture_value * 100) / 1023;
  //using formula to account for resistance
  moisture_value = 35 + (100 - moisture_value);
  
  //sending all values to the Blynk App using Virtual Pins
  Blynk.virtualWrite(V5, lux);
  Blynk.virtualWrite(V6, dht11.readCelsius());
  Blynk.virtualWrite(V7, dht11.readHumidity());
  Blynk.virtualWrite(V8, moisture_value);
  Blynk.virtualWrite(V0, water_level());

}
void setup() {
  //Setting pins from Ultrasonic Sensor
  pinMode(TRIGGER_PIN1, OUTPUT);
  pinMode(ECHO_PIN1, INPUT);
  
  SerialUSB.begin(9600);
  Blynk.begin(auth, ssid, pass);
  // Setup a function to be called every 5 seconds
  timer.setInterval(5000L, myTimerEvent);
}


void loop() {
  Blynk.run();
  timer.run(); // Initiates BlynkTimer

//for watering the crop below 60 moisture level
  if(moisture_value < 60)
  {
    digitalWrite(motorA1,HIGH);
    digitalWrite(motorA2,LOW);
    delay(100);
    digitalWrite(motorA1,LOW);
    digitalWrite(motorA2,LOW);

  }
}


int water_level() {
  
  digitalWrite(TRIGGER_PIN1, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIGGER_PIN1, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIGGER_PIN1, LOW);


  // Read the signal from the sensor: a HIGH pulse whose
  // duration is the time (in microseconds) from the sending
  // of the ping to the reception of its echo off of an object.
  pinMode(ECHO_PIN1, INPUT);
  duration = pulseIn(ECHO_PIN1, HIGH);
  
  // Convert the time into a distance
  cm = (duration*0.0348)/2;
  
//for email warning
//sending email when water level falls below 3
  if (cm < 3)
  {
    Blynk.email("Water level alert", "Fill water in the container");
  }

  return cm;
}

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