// This is very much a work in progress by a clueless amateur so please disregard all the errors!
// Purpose is to activate a cooling circuit via relay when the temp gets hotter than target
//
#include <LiquidCrystal_I2C.h>
int reading = 0;
int sensorPin = A0;
int relay =7;
const int up_key = 10;
const int down_key = 9;
int SetPoint = 30;   // Start-up setpoint - adjustable with push keys
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
//
lcd.init();      // initialize the lcd
lcd.backlight(); // open the backlight
//
pinMode(relay,OUTPUT);
pinMode(up_key, INPUT);
pinMode(down_key, INPUT);
digitalWrite(up_key, HIGH);           // Pull up for setpoint button
digitalWrite(down_key, HIGH);           // Pull up for setpoint button
pinMode(13, OUTPUT);                  // LED output
}

void loop() {
reading = analogRead(sensorPin);
int celsius = reading/2;
lcd.setCursor(0, 0);                 // Setting cursor position to row 1 char 1
lcd.print("Spa Temp: ");
//lcd.setCursor(0,1);
lcd.print((celsius/10), DEC);       // Creating a plausible value from the potentiometer in place of a temp sensor..
lcd.print((char)223);               // the degree symbol
lcd.print("C");
if ((celsius/10) > SetPoint)
{
digitalWrite(7,HIGH);         // Relay output if temp is over setpoint
digitalWrite(13, HIGH);       // LED output for same
}
else

{digitalWrite(7,LOW);         // Relay output if temp is under setpoint
digitalWrite(13, LOW);        // LED output for same
}
//
if (digitalRead(up_key) == LOW)     // "Up" input for setpoint
  {
    if (SetPoint < 40)
    {
      SetPoint++;
    }
  }
if (digitalRead(down_key) == LOW)     // "Down" input for setpoint
  {
    if (SetPoint > 20)
    {
      SetPoint--;
    }
  }
  lcd.setCursor(0, 1);            // Set cursor position
  lcd.print("Target:   ");           // Display Set point on LCD
  lcd.print(SetPoint);
  lcd.print((char)223);
  lcd.print("C");
delay(400);
// lcd.clear();
}