/*
pin A1 is the analogue voltage from the sensor on the Auger motor
pin A2 is the analogue voltage from the sensor on the Circulating Pump motor
pin 5 controls the relay for supplying power to the stove
pin 6 is the remote signal for STOVE_INHIBIT 
LCD display (20x4 chars) attached to the I2C bus as follows (address = 0x27):
        SDA - pin A4
        SCL - pin A5	
*/

#include <LiquidCrystal_I2C.h>

#define I2C_ADDR    0x27
#define LCD_COLUMNS 20
#define LCD_LINES   4

LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);


int pinVal = 0;  //analogue voltage read from pin A1
unsigned long readPrev = 0;    //last time that pin A1 was read
const long readInterval = 1000;    //interval (ms) for reading pin A1
unsigned long highPrev = 0;    //last time (ms) that pin A1 was HIGH
unsigned long highMax = 5000;    //max length of time (ms) after pin A1 goes LOW before COOLING starts
unsigned long coolInterval = 5000;    //length of time (ms) for cooling before switch off
bool circPump = false;    //true if circulating pump is running


void setup() {
  Serial.begin(9600);
  delay(123);    //add a short delay before initialising highPrev
  highPrev = millis();

  pinMode(5, OUTPUT);
  digitalWrite(5, HIGH);    //turn stove power ON

  pinMode(6, INPUT_PULLUP);    //pin 6 is the remote "stove_inhibit" signal

  lcdInit();
  lcdLine(0, 0, "Ready ...");
  lcdLine(0, 2, "Press Start on the");
  lcdLine(0, 3, "stove control panel");

  //hang here until the first signal on pin A1
  Serial.print("READY - waiting for first signal from Auger motor (pin A1) ...");
  do {
    pinVal = analogRead(A1);    //read pin A1
  } while (pinVal <= 500);
  Serial.println(" STARTING");  
}

void lcdInit() {
  //initialise the LCD screen
  lcd.init();
  lcd.backlight();
  return;
}


void lcdLine(int lineNo, int colNo, const char *txt) {
  //display text on LCD starting at given line no and col no
  lcd.setCursor(lineNo, colNo);
  lcd.print(txt);
  return;
}


void loop() {
  unsigned long readCurr = millis();    //current time 

  //read pin A1 and remote stove_inhibit signal every [readInterval] ms
  if (readCurr - readPrev >= readInterval) {
    readPrev = readCurr;
    Serial.print("RUNNING");
    lcdInit();

    //check whether the circulating pump is running
    pinVal = analogRead(A2);    //read pin A2
    if (pinVal > 500){
      circPump = true;
      lcdLine(1, 0, "Running - pump ON");
      Serial.print(" - PUMP ON");
    }
    else {
      circPump = false;
      lcdLine(1, 0, "Running - pump OFF");
      Serial.print(" - PUMP OFF");
    }

     pinVal = analogRead(A1);    //read pin A1
    
    if (pinVal > 500) {
      highPrev = 0;    //reset the time since the pin was last HIGH (defined as >2.5V)
    }
    else {
      highPrev = highPrev + readInterval;    //else increment the time since it was last HIGH
    }
    
    Serial.print(" pin A1="); Serial.print(pinVal); Serial.print(" highPrev="); Serial.println(highPrev);

    if (highPrev > highMax) {
      Serial.println("COOLING");
      lcdInit();
      lcdLine(4, 0, "Cooling ...");
      lcdLine(3, 2, "Do NOT switch");
      lcdLine(5, 3, "power off");
      delay(coolInterval);
      
      digitalWrite(5, LOW);    //turn off stove power and hang here if time exceeded

      Serial.println("COLD");
      lcdInit();
      lcdLine(7, 0, "COLD");
      lcdLine(2, 2, "Switch power off");
      lcdLine(3, 3, "at wall socket");  
 
    do {
       } while (true);

    }

    //check for remote "stove_inhibit" signal
    pinVal = digitalRead(6);   //read pin 6
      if (!pinVal) {
        digitalWrite(5, HIGH);
        //turn off power and hang here if remote "stove_inhibit"
        digitalWrite(5, LOW); 
        lcdInit();
        lcdLine(0, 0, "Off (stove_inhibit)");
        lcdLine(2, 2, "Switch power off");
        lcdLine(3, 3, "at wall socket");

        Serial.println(" STOVE_INHIBIT");
        do {
           } while (true); 
    }

  }

}