Smart Thermostat Arduino - part sensors

smarttherm_part_sensors.ino

//code snippet from: https://github.com/niektemme/smarttherm-arduino/blob/master/arduino-sketch/smarttherm.ino
//ref voltage
#define aref_voltage 3.3       

//variables for settemp variable resistor
int sensorPin = 0; //sensor = settemp
int sensorValue = 0;
int sensorOldValue = 0;

//variables for TMP36
int temperaturePin = 1; //act temp
int tempValue = 0;
int tempOldValue = 0;
int tempDisValue = 0;
int tempDisOldValue = 0;

//variables for boiler on off sensor (photo resistor)
int boilerPin = 2;
int boilerValue = 0;

//variables for thermistor
int thermistorPin= 3;
int thermistorValue =0;
int thermistor2Pin= 4;
int thermistor2Value =0;
...

void setup() {
  analogReference(EXTERNAL); //analogue refference
  ...
}

void loop() {
...
  float temperature = tempReading(temperaturePin);  //getting the voltage reading from the temperature sensor
  temperature = (temperature - .5) * 100;          //converting from 10 mv per degree wit 500 mV offset
   //to degrees ((volatge - 500mV) times 100)
  tempValue = (int) (temperature*100);

  //reading boiler on of state
  float boiler = getVoltage(boilerPin);
  boilerValue = (int) (boiler*100);

  //avaraging set temperature to .5 degrees celcius
  float sensorCalcValue = (round(((analogRead(sensorPin)/5.0)+100.0)/10.0*2.0))/2.0*10.0;
  sensorValue = (int) sensorCalcValue;

  //Reading thermistor 1 value using thermistorRead() function, sending nominal value and bcofficient (steinhart) to function
  float thermistor = thermistorRead(thermistorPin,10000,10000,25,3950);
  thermistorValue = (int) (thermistor*100);

  //Reading thermistor 2 value using thermistorRead() function, sending nominal value and bcofficient (steinhart) to function
  float thermistor2 = thermistorRead(thermistor2Pin,100000,100000,25,4261);
  thermistor2Value = (int) (thermistor2*100);

...

}

//function to get analoge value to digital range
float getVoltage(int pin){
   return (analogRead(pin) * .004882814); //converting from a 0 to 1023 digital range
                                        // to 0 to 5 volts (each 1 reading equals ~ 5 millivolts
 }  

//tmp36 sensor fucntion
float tempReading(int pin){
  int tempRead = analogRead(pin);
  float voltage = tempRead * aref_voltage;
  voltage /= 1024.0;
  return voltage;
}

//function for read thermistor value given nominal value and bcofficient (steinhart)
float thermistorRead(int pin, int seriesr, int thermistnominal,int tempnom, int bcof) {
  float tempRead = analogRead(pin);

  // convert the value to resistance
  tempRead = 1023 / tempRead - 1;
  tempRead = seriesr / tempRead;

  float steinhart;
  steinhart = tempRead / thermistnominal;     // (R/Ro)
  steinhart = log(steinhart);                  // ln(R/Ro)
  steinhart /= bcof;                   // 1/B * ln(R/Ro)
  steinhart += 1.0 / (tempnom + 273.15); // + (1/To)
  steinhart = 1.0 / steinhart;                 // Invert
  steinhart -= 273.15;                         // convert to C

  return steinhart;
}