GUI - Heating Device with PID Temperature Control

1/*///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
2                  UNIVERSIDADE FEDERAL DE PERNAMBUCO - PHYSICS DEPARTMENT - NANO-OPTICS  LABORATORY
3                                            HEATING DEVICE - PID CONTROLLER
4                                                    Allison Pessoa
5
6                                              Recife,  Pernambuco - Brazil
7                                                      September  2020
8                                                allisonpessoa@hotmail.com
9
10This  heating device acts to hold at a constant temperature (user-defined setpoint) a  thermal blancket by using a PID controller. 
11A thermistor is used for temperature  sensing (input), and a silicone mat for heating (PWM output). The User Interface  can receive the temperature data
12and/or send the P,I,D,Setpoint parameters using  Serial Communication.
13
14Commands:
15
16-> 'SETPT(value)' : Sets the temperature  in which the temperature must be held constant.
17-> 'UPDSETT(val1,val2,val3)'  : Redefines the PID constants. val1 = P; val2 = I, val3 = D
18
19**The User-Interface  must avoid invalid values.
20
21Pins Interface:
22
23-> Pin D5 -> Thermal Blancket  (Heater) | PWM 0-5V, 980 Hz, Output
24-> Pin A1 -> Thermistor | Analog Input (0-5V)
25
26
27under  GNU GPLv3 License
28
29////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////*/
30#include  "thermistor.h"
31#include <PID_v1.h>
32
33#ifdef VERBOSE_SENSOR_ENABLED //  undefine a macro from thermistor library
34  #undef VERBOSE_SENSOR_ENABLED // so  it do not print other things than the temperature value
35#endif 
36
37#define  NTC_PIN_INPUT A1 //Pin to NTC input
38#define PWM_PIN_OUTPUT 5 //Pin to PWM output
39
40THERMISTOR  thermistor(NTC_PIN_INPUT,  // Analog pin
41                      10000,          //  Nominal resistance at 25 C
42                      3950,           // thermistor's  beta coefficient
43                      10000);         // Value of the series  resistor
44
45// User Interface releated
46double control_P = 100;
47double  control_I = 10;
48double control_D = 1;
49
50double setPoint = 20;
51double  temp; //PID Input
52double duty; //PID Output
53
54PID PID_control(&temp, &duty,  &setPoint, control_P, control_I, control_D, DIRECT);
55
56// Communication through  USB
57typedef struct {
58  String content;
59  volatile uint32_t value[3];   //  three parameters function, maximum
60}Command;
61
62Command ReadCommand() {
63//Indetifies  the command, splits letters and numbers, saves the numbers as arguments
64    Command  aux;
65    char number[10];
66    char *eprt;
67    int ascii;
68    int i=0,  j=0, l=0;
69
70    while(Serial.available()>0) {
71      ascii=Serial.peek();
72      if(ascii != 13) {//if it is not \\enter (CR)
73        if (ascii > 47 &&  ascii < 58) {//numbers
74          delay(10);
75            do {
76              number[i]=  Serial.read();
77              ascii = Serial.peek();
78              i++;
79            } while (ascii > 47 && ascii < 58);
80
81          i=0;
82          long  int var = strtol(number,&eprt,10);
83          aux.value[j] = var;
84
85          for  (int k=0; k<10;k++){
86            number[k]=0;
87          }
88          j++;
89        }
90        else {//letters
91          char charac = Serial.read();
92          if (charac > 96 && charac < 123){
93            charac -= 32;//only uppercase  letters
94          }
95          aux.content.concat(charac);
96        }
97      }
98      delay(10);
99    }
100    return aux;
101}
102
103
104void setup(){
105  pinMode(PWM_PIN_OUTPUT, OUTPUT); //PWM Output
106  Serial.begin(9600);
107  PID_control.SetMode(AUTOMATIC);
108
109  //First measurement
110  temp = float(thermistor.read())/10;
111  Serial.print("A");
112  Serial.println(temp);
113}
114
115void loop (){
116  Command rec;
117  if (Serial.available()){
118    rec = ReadCommand();
119    
120    if (rec.content == "SETPT()"){ //if you  whish to control directly throught Serial Monitor, use "SETPT()\
121" instead (at  least, for Ubuntu users. Arduino 1.8.12).
122      setPoint = float(rec.value[0])/10;  //Receive temperature in x10 C
123    }
124    
125    if (rec.content == "UPDSETT(,,)"){//The  user interface must avoid invalid values
126      control_P = rec.value[0];
127      control_I = rec.value[1];
128      control_D = rec.value[2];
129    }
130  }
131  
132  for(int i=0; i<10; i++){
133    temp = float(thermistor.read())/10;  //Receive temperature in x10 C
134    if ((temp - setPoint) < 0.5) { //Setting adaptive  tunings
135      temp = float(thermistor.read())/10;
136      PID_control.Compute();
137      analogWrite(PWM_PIN_OUTPUT, duty);//980 Hz (predefined), at this pin
138      delay(10);  
139    }
140    else{
141      digitalWrite(PWM_PIN_OUTPUT, 0);
142      delay(10);  
143    }
144  }
145
146  Serial.print("A");
147  Serial.println(temp);
148}
149