/* NOTE:


External Thermostat using a DS18S20.
This uses two relays hotwired
into a cheap home automation RF remote
to turn one channel on and off.

planning to run this on an ATTiny45

by Non-ICE

edit:
needed to add some self check indicators
since this still is a breadboardbuild

edit II:
this code is attiny45-ready

edit III:
screw tiny45; code is attiny25-ready
*/

#include <OneWire.h>

float settemp=33.0; //wanted temperature in celsius 
int DS18S20_Pin = 3; //DS18S20 Signal pin on digital 0
int tempfailcount=0;
int pump = 4; //inverted for security off = pump running
int heater = 5; //relay for 1kW heater
int ledpin = 13;
int switchdelay = 60; //minimum delay in seconds between each toggle.

//no changes needed below this point.
int modechange = 15; //toggle timer counter, 15 seconds after boot
int heatstate; //toggle state holder

int blinktemp;
//Temperature chip i/o
OneWire ds(DS18S20_Pin); // on digital pin 3

void setup(void) {
  pinMode(ledpin, OUTPUT);
  pinMode(pump, OUTPUT);
  pinMode(heater, OUTPUT);
  digitalWrite(pump, HIGH); //stop pump
  digitalWrite(heater, LOW); //stop heater
  
  //debug
  Serial.begin(9600);
}

void loop(void) {
  float temperature = getTemp();
  Serial.println(temperature);  //debug
  
  //blink temperature
  blinktemp=temperature/10;
  while (blinktemp>0) {
    digitalWrite(ledpin, HIGH);
    delay(5);
    digitalWrite(ledpin, LOW);
    delay(300);
    blinktemp--;
    }
    delay(800);
    blinktemp = temperature/10;
    blinktemp = temperature - (10*blinktemp);
    //Serial.println(blinktemp);  //debug
    while (blinktemp>0) {
    digitalWrite(ledpin, HIGH);
    delay(5);
    digitalWrite(ledpin, LOW);
    delay(300);
    blinktemp--;
    }
  delay(1000);
  
  //do your job, safety first
  if (temperature > 40 || temperature < 5) { 
    //if input data  is way off something is wrong give some indication
    tempfailcount++;
    digitalWrite(ledpin, HIGH);
    delay(5000);
    
    if (tempfailcount >= 60) { //controlled stop if over 60 fails
      digitalWrite(heater, LOW); //stop heater
      delay(10000);
      digitalWrite(pump, HIGH); //stop pump
      heatstate=false;
    }
    digitalWrite(ledpin, LOW);
    
    
  } else {
    // all ok, do heater toggle
    tempfailcount = 0;
      if (temperature < (settemp)) {
        if (heatstate == false){
          heatstate=true;
          Serial.println("Heat ON sequence started.");  //debug
          digitalWrite(pump, LOW); //start pump
          delay(20000); //20 seconds priming of the pump and heater
          digitalWrite(heater, HIGH); //start heater
          delay(20000); //20 sec min heatingtime
        }
      }
      else {
        if (heatstate == true && temperature >= (settemp + 0.25)){
          heatstate=false;
          Serial.println("Heat OFF sequence started.");  //debug
          digitalWrite(heater, LOW); //stop heater
          delay(60000); //1 minutes cooling the heater for safety
          digitalWrite(pump, HIGH); //stop pump
        }
      }
    }

}



float getTemp(){
//returns the temperature from one DS18S20 in DEG Celsius

byte data[12];
byte addr[8];


// error checking
if ( !ds.search(addr)) {
  //no more sensors on chain, reset search
  ds.reset_search();
  return -1000;
}

if ( OneWire::crc8( addr, 7) != addr[7]) {
  //Serial.println("CRC is not valid!");
  return -1000;
}

if ( addr[0] != 0x10 && addr[0] != 0x28) {
  //Serial.print("Device is not recognized");
  return -1000;
}


//read DS
ds.reset();
ds.select(addr);
ds.write(0x44,1); // start conversion, with parasite power on at the end

byte present = ds.reset();
ds.select(addr);
ds.write(0xBE); // Read Scratchpad


for (int i = 0; i < 9; i++) { // we need 9 bytes
data[i] = ds.read();
}

ds.reset_search();

byte MSB = data[1];
byte LSB = data[0];

float tempRead = ((MSB << 8) | LSB); //using two's compliment
float TemperatureSum = tempRead / 16;

return TemperatureSum;

}