Automatic FART EXTRACTOR / Bathroom Dehumidifier Fan

1/* Automatic fan control for bathroom humidity
2 * humidity threshold  set by a potentiometer 30<->90%
3 * pushbutton for manual activation 15 minutes
4  * 
5 *  Viorel Racoviteanu
6 *  https://www.youtube.com/channel/UCiRLZX0bV9rS04BGAyUf-fA
7  *  https://racov.ro
8 *  YO3RAK@gmail.com
9 *  
10 * I cannot take any responsibility  for missuse of this code
11 * or any kind of damage it may occur from using this  code.
12 * 
13 * nov 2022 - first release
14*/
15
16//Libraries
17#include  <DHT.h>;
18DHT sensor(3, DHT22);   // Initialize DHT22 on pin 3
19
20//Variables
21unsigned  long NowTime;    //Store the current millis() for timing purposes
22int hum_set;              //Stores set humidity threshold
23int hum_read;             //Stores  real humidity
24int temp;                 //Stores real temperature
25String fan;               //colud be ON of OFF, for serial display
26
27void setup()
28{
29//  pin declaration
30  pinMode(A6, INPUT);     //potentiometer pin
31  pinMode(3,  INPUT);      //DHT22 sensor pin
32  pinMode(4, OUTPUT);     //relay pin
33  pinMode(13,  OUTPUT);    //LED pin
34  Serial.begin(9600);
35  sensor.begin();
36  
37//  splashscreen
38  Serial.println();
39  Serial.println("     *****    FART EXTRACTOR,  nov.2022    *****");
40  Serial.println("Viorel Racoviteanu, https://racov.ro,  YO3RAK@gmail.com");
41  Serial.println();
42
43  digitalWrite(13, HIGH); //  activate relay and led
44  digitalWrite(4, HIGH);
45// the reset is manual activation  for 15 minutes
46  Serial.println("Manual activation 15 minutes");
47  Serial.println();
48  for (int i = 0; i<(15*60); i++){
49    delay (1000);
50  }
51  NowTime = millis();
52  digitalWrite(13, LOW);
53  digitalWrite(4, LOW);
54  fan = "OFF";
55  NowTime  = millis();
56}
57
58void loop()
59{
60//Read the potentiometer for set humidity  threshold
61//transforms potentiometer voltage into threshold value
62  hum_set  = (map(analogRead(A6), 0, 1023, 30, 90));
63//Read sensor data every 2 seconds
64  hum_read = sensor.readHumidity();
65  temp= sensor.readTemperature();
66//Print  temp and humidity values to serial monitor
67  digitalWrite(13, HIGH);     //blink  LED
68  Serial.print("Rh%:");
69  Serial.print(hum_read);
70  Serial.print(",  Set:");
71  Serial.print(hum_set);
72  Serial.print(", Temp:");
73  Serial.print(temp);
74  Serial.print(", Fan-");
75  Serial.println(fan);
76  delay (100);
77  digitalWrite(13,  LOW);
78//if threshold exceeded
79  if(hum_read > hum_set) {
80    fan = "ON";
81    digitalWrite(4, HIGH);    //activate relay and led
82    digitalWrite(13, HIGH);
83  }
84//if threshold not exceeded (with hysteresis)
85  if(hum_read < (hum_set-3))  {
86    fan = "OFF";
87    digitalWrite(4, LOW);    //deactivate relay
88  }
89  delay(2000);
90}
91