// Gravity: Analog pH Sensor/Meter Kit V2 with Arduino
// This code reads the analog voltage from the pH sensor and converts it to a pH value.
// The sensor is connected to the analog pin A0 of the Arduino.
// The output is displayed in the Serial Monitor.

// Pin assignment
const int phPin = A0;  // Analog input pin for pH sensor

// Variables to store sensor values
float voltage;  // Voltage read from the sensor
float pHValue;  // Calculated pH value

void setup() {
  // Initialize serial communication at a baud rate of 9600
  Serial.begin(9600);
  Serial.println("pH Sensor Calibration and Reading");
}

void loop() {
  // Read the analog input from the pH sensor
  int sensorValue = analogRead(phPin);
  
  // Convert the analog reading (0 - 1023) to a voltage (0 - 5V)
  voltage = sensorValue * (5.0 / 1023.0);
  
  // Convert the voltage to a pH value using the formula:
  // pH = 7 + ((2.5 - voltage) / 0.18)
  // This formula is derived from the sensor's characteristics and calibration
  pHValue = 7 + ((2.5 - voltage) / 0.18);

  // Print the results to the Serial Monitor
  Serial.print("Voltage: ");
  Serial.print(voltage);
  Serial.print(" V, pH: ");
  Serial.println(pHValue);

  // Wait for 1 second before taking the next reading
  delay(1000);
}