#include <Wire.h>

float calibration_value = 21.34 + 3;
int phval = 0;
unsigned long int avgval;
int buffer_arr[10],temp;
float pH_act;
byte string_received = 0;

const int Pump_1 = 2;  // the Arduino pin, which connects to the pin of relay
const int Pump_2 = 3;  // the Arduino pin, which connects to the pin of relay

void setup() {
    Wire.begin();
    Serial.begin(9600);
    pinMode(Pump_1, OUTPUT);
    pinMode(Pump_2, OUTPUT);
}

void loop() {
    // put your main code here, to run repeatedly:
    for(int i=0;i<10;i++)
    {
        buffer_arr[i]=analogRead(A0);
        delay(30);
    }
    for(int i=0;i<9;i++)
    {
        for(int j=i+1;j<10;j++)
        {
            if(buffer_arr[i]>buffer_arr[j])
            {
                temp=buffer_arr[i];
                buffer_arr[i]=buffer_arr[j];
                buffer_arr[j]=temp;
            }
        }
    }
    avgval=0;
    for(int i=2;i<8;i++)
    {
        avgval+=buffer_arr[i];
    }
    float volt=(float)avgval*5.0/1024/6;
    pH_act = -5.70 * volt + calibration_value;

    Serial.println("pH Val: ");
    Serial.print(pH_act);
    delay(1000);

    if (pH_act < 6.5) {     //test condition against pH reading
        Serial.println("PH LEVEL LOW,Pump_1 = ON");
        digitalWrite(Pump_1, HIGH);
        delay(3000);
        //if condition is true, send command to turn on pump (called PMP_UP) and dispense pH up solution, in amounts of 0.5ml. Pump turns clockwise.
    }
    else {
        digitalWrite(Pump_1, LOW);      //if condition is false, send command to turn off pump (called PMP_UP)
    }

    if (pH_act > 7.5) {     //test condition against pH reading
        Serial.println("PH LEVEL HIGH,Pump_2 = ON");
        digitalWrite(Pump_2, HIGH);
        delay(3000);        //if condition is true, send command to turn on pump (called PMP_DOWN) and dispense pH down solution, in amounts of 0.5ml. Pump turns counter-clockwise.
    }
    else {
        digitalWrite(Pump_2, LOW);      //if condition is false, send command to turn off pump (called PMP_DOWN)
    }
    Serial.println();
}