Heating_System_PID.ino

#include<math.h>
#include<PID_v1.h>
//Define constants for Temperature calculation
const int transistorPin = 9;
int ThermistorPin= A0; //define thermistor
int Vo;
float R1=10000;
float logR2, R2, T;
float c1= 1.009249522e-03, c2=2.378405444e-04,c3=2.019202697e-07;
float target_value = 30.0;

//Define constants for PID control
double SetPoint;
double Input;
double Output;
double Kp=0,Ki=5,Kd=0;

//create PID instance
PID myPID(&Input,&Output,&SetPoint,Kp,Ki,Kd,DIRECT);


void setup (){

  Serial.begin(9600) ;
  pinMode (transistorPin, OUTPUT) ;
  pinMode (ThermistorPin, INPUT) ;

  //Setting parameters for PID
  SetPoint=target_value-5;
  myPID.SetMode(AUTOMATIC);
  myPID.SetTunings(Kp,Ki,Kd);
  
}
void loop (){
  
//Temperature Detection
  Vo=analogRead(ThermistorPin) ;
  R2=R1* (1023.0/(float)Vo-1.0) ;
  logR2=log(R2);
  T=(1.0/(c1+c2*logR2+c3*logR2*logR2*logR2) ) ;
  T=T-273.15;
  Serial.print("Temperature=");
  Serial.print(T);
  Serial.print("C ");
  //delay (1000) ;

  Input=T;
  myPID.Compute();
  
//Controller
  if (T<target_value-0.5){
    analogWrite(transistorPin,Output);
    //delay(100);
    Serial.println(Output);
  }
  else if(T>=target_value+0.5){
    analogWrite(transistorPin,Output);
    //delay(100);
    Serial.println(Output);
  } 
  
}