Auto Calibration Program for Capacitive Soil Moisture Sensor

//You need to use a 16x2 LCD display. There are plenty of tutorials on how to connect these to your arduino. Just make sure the pins are correct.

#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 7, 6, 5, 4);



int AirValue = 600;   //This is the sensor value when completely dry.
int WetValue = 250;  //This is the sensor value when submerged in water.
unsigned long timeReadingWet = 60000; //This is the time the sensor needs to reach the full wet value (in milliseconds).
unsigned long timeReadingAir = 10000; //This is the time the sensor needs to reach the full air value (in milliseconds).
byte CalibrationButton = 8; //This is the pin number for the button (you don't need any resistors, the Arduino uses an internal one when declared as INPUT_PULLUP (below).




void setup() {

  Serial.begin(9600);
  
  lcd.begin(16, 2); 

  pinMode(CalibrationButton, INPUT_PULLUP); //This is where you declare your button pin as INPUT_PULLUP.

}

void loop() {




// This is the guided program that calibrates your capacitive soil moisture sensor. Just add it to your exising code!



  if (digitalRead(CalibrationButton) == LOW) { //when the button is pressed

    lcd.setCursor(0, 0);
    lcd.print("Let's calibrate");
    lcd.setCursor(0, 1);
    lcd.print("the sensor");
    delay(3000);
    lcd.clear();


    while (digitalRead(CalibrationButton) == HIGH) { //the program waits for the user to press the button again

      
      lcd.setCursor(0, 0);
      lcd.print("Dry sensor");
      lcd.setCursor(0, 1);
      lcd.print("completely B"); //the B stands for Button, it tells the user that the button needs to be pressed to continue


      if (digitalRead(CalibrationButton) == LOW) { //this happens when the button is pressed again

        lcd.clear();

        for (unsigned long timeStartAir = millis(); (millis() - timeStartAir) < timeReadingAir; ) { //this loop reads the sensor for timeReadingAir (defined in the header)
          AirValue = max(analogRead(0), AirValue);
          lcd.setCursor(0, 0);
          lcd.print("Calibrating");
          lcd.setCursor(0, 1);
          lcd.print("for air ");
          lcd.print((timeReadingAir/1000)-(millis() - timeStartAir)/1000); //then displays the time remaining
          lcd.print("s  ");
          Serial.println(AirValue);

        }

        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("Air value");
        lcd.setCursor(0, 1);
        lcd.print("established: "); //then it lets the user know that the reading was established (then prints it)
        lcd.print(AirValue);
        Serial.println(AirValue);
        delay(5000);

        lcd.clear();


        while (digitalRead(CalibrationButton) == HIGH) { //same thing but for wet



          lcd.setCursor(0, 0);
          lcd.print("Now submerge");
          lcd.setCursor(0, 1);
          lcd.print("in water B");

          if (digitalRead(CalibrationButton) == LOW) {

            lcd.clear();

            for (unsigned long timeStartWater = millis(); (millis() - timeStartWater) < timeReadingWet; ) {
              WetValue = min(analogRead(0), WetValue);
              lcd.setCursor(0, 0);
              lcd.print("Calibrating");
              lcd.setCursor(0, 1);
              lcd.print("for wet ");
              lcd.print((timeReadingWet/1000)-(millis() - timeStartWater)/1000);
              lcd.print("s  ");
              Serial.println(WetValue);

            }

            lcd.clear();

            lcd.setCursor(0, 0);
            lcd.print("Wet value");
            lcd.setCursor(0, 1);
            lcd.print("established: ");
            lcd.print(WetValue);
            Serial.println(WetValue);
            delay(5000);

            lcd.clear();

            lcd.setCursor(0, 0);
            lcd.print("Calibration");
            lcd.setCursor(0, 1);
            lcd.print("successful");

            Serial.println(WetValue);
            delay(5000);
            lcd.clear();


            return;

          }


        }



      }

    }

  }

}