Humidity Controller

A simple device that makes controlling humidity and saving energy a snap. Operates as easily as a thermostat.

Aug 8, 2019

•

19616 views

•

13 respects

energy efficiency

smart appliances

health

Components and supplies

resistor 2k ohm

5V 2.5A Switching Power Supply

grounded power cable

Resistor 10k ohm

yellow wire nuts

Alphanumeric LCD, 16 x 2

Arduino Nano R3

Decora 2-Gang Midway Nylon Wall Plate - White

decora duplex outlet, white

Jumper wires (generic)

2-Gang 47 cu. in. PVC New/Old Work Electrical Box (B249B)

Grove - 2-Channel SPDT Relay

DHT11 Temperature & Humidity Sensor (3 pins)

Tools and machines

Soldering iron (generic)

Project description

Code

Humidity controller code

c_cpp

code for operating the humidity controller

1//HUMIDITY CONTROLLER 1.1
2//written for NANO
3
4//controls and   displays relative humidity
5//sesnor used is DHT11
6//uses active-low relay   module to control live lines for 2 standard electrical outlets
7//uses i2c lcd   to display humidity and humidity setting
8//turns display off during inactivity
9//setting   is adjustable from 10%-90% using 2 buttons
10//backlight of LCD is controlled by   pin 4, connected to top LED jumper pin on i2c backpack
11//serial communications   to monitor to ensure all code is working.
12
13//added: "system off" function   - allows both outlets to be turned off
14
15// █ G █ L █ O █ B █ A █ L █ S █
16#include   <Wire.h>
17#include <LiquidCrystal_I2C.h>
18#include <dht.h>
19
20// set the   LCD address to 0x27 for a 16 chars and 2 line display
21LiquidCrystal_I2C lcd(0x27,   16, 2);  
22
23dht DHT;
24
25#define DHT11_PIN A2
26
27//buttons and variables   to adjust calibration
28int calupbtn = A0;
29int calup;
30int caldownbtn = A1;
31int   caldown;
32
33//i2c PINS A4, A5
34
35//pin for turning on humidifier relay
36int   humidifier = 3;
37//pin for turning on the fan relay
38int fan = 2;
39//pin for   turning on LCD backlights
40int lcdlight = 4;
41
42//calibration variable
43int   setpoint = 50;  //feedback setpoint.  
44bool calstate = false;  //enables calibration   adjustments only when LCD is ON.
45
46//backlight timing variables
47int displtime   = 12000;  //amount of time the display is to be on before turning off
48unsigned   long displtimeon;  //last recorded time display timer was reset
49int calunlock   = 0;   //loop counter for unlocking calibration  
50
51//sensor timing variables
52unsigned   long lastcheck;  //last time DHT was read
53long interval = 30000;      //time   between DHT readings
54
55//system variables
56bool syson = true;    //reference   for system on/off. 
57byte systog = 2;       //even number toggles on, odds toggle   off
58int syslock = 0;     //loop counter for unlocking system toggle
59
60//   █ S █ E █ T █ U █ P █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █
61void   setup(){
62
63  Serial.begin(9600);  //serial communication used to ensure code   is working correctly.
64  
65  lcd.init();  //initialize LCD
66  lcd.backlight();   //enable LCD backlight, but doesn't turn it on
67
68  lastcheck = 0;
69  digitalWrite(lcdlight,   HIGH);
70  Serial.println("STARTING");
71  lcd.print("   STARTING");
72
73   //pin assignments
74  pinMode(calupbtn, INPUT);
75  pinMode(caldownbtn, INPUT);
76   pinMode(humidifier, OUTPUT);
77  pinMode(fan, OUTPUT);
78  pinMode(lcdlight,   OUTPUT);
79  delay(1000);
80
81  
82  //test fan
83  lcd.setCursor(0,1);
84   lcd.print("<FAN>     HMDFR  ");  
85  digitalWrite(fan, LOW);
86  digitalWrite(humidifier,   HIGH);
87  delay(6000);
88  //test humidifier
89  lcd.setCursor(0,1);
90  lcd.print("   FAN     <HMDFR> ");
91  digitalWrite(fan, HIGH);
92  digitalWrite(humidifier,   LOW);
93  delay(6000);
94  //stop startup test
95  digitalWrite(humidifier, HIGH);
96   digitalWrite(fan, HIGH);
97  lcd.clear();
98
99  displtimeon = millis();
100
101   int chk = DHT.read11(DHT11_PIN);
102  lastcheck = millis();
103
104  lcd.setCursor(0,0);
105   lcd.print("Humidity: ");
106  lcd.setCursor(13,0);
107  lcd.print(DHT.humidity);
108   lcd.setCursor(15,0);
109  lcd.print("%  ");
110  lcd.setCursor(0,1);
111  lcd.print("setting:   ");
112  lcd.setCursor(13,1);
113  lcd.print(setpoint);
114  lcd.setCursor(15,1);
115   lcd.print("%  ");
116  delay(100);
117}
118
119// █ L █ O █ O █ P █ = █ = █   = █ = █ = █ = █ = █ = █ = █ = █ = █ = █ = █ = █ = █
120void loop(){
121
122  //check   calibration buttons
123  calup = digitalRead(calupbtn);
124  caldown = digitalRead(caldownbtn);
125
126   if(calup == HIGH and caldown == HIGH){  //--------SYSTEM TOGGLE
127    syslock   ++;
128    Serial.println(syslock);
129    if(syslock == 20){  //if both buttons   held down for this many loops
130      systog++;
131      if(systog % 2 == 1){  //--------SYSTEM   OFF
132        syson = false;
133        digitalWrite(fan, HIGH);
134        digitalWrite(humidifier,   HIGH);
135        digitalWrite(lcdlight, HIGH);
136        Serial.println("SYSTEM   TURNED OFF");
137        lcd.clear();
138        lcd.print("   SYSTEM OFF");
139         lcd.setCursor(0,1);
140        lcd.print("  hold both btns");
141        delay(2000);
142         lcd.setCursor(0,1);
143        lcd.print("  to turn on    ");
144        displtimeon   = millis();
145      }
146      if(systog % 2 == 0){  //--------SYSTEM ON
147        syson   = true;
148        Serial.println("SYSTEM TURNED ON");
149        digitalWrite(lcdlight,   HIGH);
150        lcd.clear();
151        lcd.print("   SYSTEM ON");
152        delay(2000);
153         lcd.clear();
154        displtimeon = millis();
155      }
156      syslock   = 0;
157    }
158  }
159  else(syslock = 0);
160  
161  //read humidity at appropriate   intervals
162  if(millis() > lastcheck + interval and syson == true){  //read the   DHT humidity
163    int chk = DHT.read11(DHT11_PIN);
164    lastcheck = millis();
165     Serial.print("DHT read = ");
166    Serial.print(DHT.humidity);
167    Serial.print("%");
168     Serial.println(" ");
169    }
170
171  //turn on the led lights when calibration   buttons are pressed
172  if(calup == HIGH xor caldown == HIGH){
173    digitalWrite(lcdlight,   HIGH);
174    calstate = true;
175    displtimeon = millis();  //set display timer
176     Serial.println("cal btn ACTIVE");
177    if(syson == false){
178      digitalWrite(lcdlight,   HIGH);
179      lcd.clear();
180      lcd.print("   SYSTEM OFF");
181      lcd.setCursor(0,1);
182       lcd.print("  hold both btns");
183      delay(3000);
184      lcd.setCursor(0,1);
185       lcd.print("  to turn on    ");
186      displtimeon = millis();
187    }
188   }
189
190  if(calstate == true and syson == true){  //--------DISPLAY ROUTINE
191     Serial.println("printing display");
192    //display variables on LCD
193     lcd.setCursor(0,0);
194    lcd.print("Humidity: ");
195    lcd.setCursor(13,0);
196     lcd.print(DHT.humidity);
197    lcd.setCursor(15,0);
198    lcd.print("%  ");
199     lcd.setCursor(0,1);
200    lcd.print("setting: ");
201    lcd.setCursor(13,1);
202     lcd.print(setpoint);
203    lcd.setCursor(15,1);
204    lcd.print("%  ");
205     delay(100);
206
207    calunlock ++;  
208    //keeps calibration locked until   display cycles 5 times after initially turned on
209    //prevents adjustments on   initial button press.
210  }
211
212//--------CALIBRATION ADJUSTMENTS
213  if(calup   == HIGH and caldown == LOW and calstate == true and syson == true){ 
214    if(setpoint   < 90 and calunlock > 5){ 
215      setpoint = setpoint + 5;  //increase setpoint   
216      Serial.println("adj setpoint up");
217    }
218    Serial.println(setpoint);
219     delay(100);
220    displtimeon = millis();     //reset backlight timeout
221   }
222
223  if(caldown == HIGH and calup == LOW and calstate == true and syson   == true){
224    if(setpoint > 10 and calunlock > 5){
225      setpoint = setpoint   - 5;  //decrease setpoint
226      Serial.println("adj setpoint dn");
227      }
228     Serial.println(setpoint);
229    delay(100);  
230    displtimeon = millis();      //reset backlight timeout
231  }
232
233  if(millis() > displtimeon + displtime){   //-----------------BACKLIGHT TIMEOUT
234    digitalWrite(lcdlight, LOW); //turn   off the screen
235    calstate = false;
236    Serial.println("displ + backlights   off");
237    lcd.clear();
238    calunlock = 0;  //lock calibration
239  }
240
241   if(millis() < lastcheck){
242    lastcheck = millis();  //reset timers in a millisecond   rollover
243  }
244
245                                      //--------SETPOINT   ERROR PROCEDURE
246  if(setpoint > 91 or setpoint < 9){  //in case setpoint is ever   out of bounds
247    Serial.println("O/B ERROR");
248    digitalWrite(lcdlight,   HIGH);
249    lcd.clear();
250    lcd.print("O/B ERROR");  //display error message   on lcd
251    lcd.setCursor(0,1);
252    lcd.print("RESETTING");
253    delay(1000);
254     for(int count = 9; count >= 0; count = count - 1){
255      lcd.setCursor(15,1);
256       lcd.print(count);     //count down from 10
257      delay(1000);
258    }
259     setpoint = 50;        //reset setpoint at 50.
260    displtimeon = millis();
261   }
262
263  //turn on humidifier relay if below setpoint  --------RELAY CONTROL
264   //RELAY MODULE IS ACTIVE LOW
265  if(DHT.humidity <= setpoint - 3 and syson ==   true){  //if humidity is 3% lower than setpoint
266    Serial.println("humidifier   ON, fan OFF");  
267    digitalWrite(humidifier, LOW);  //turn on humidifier
268     digitalWrite(fan, HIGH);
269  }
270  else if(DHT.humidity >= setpoint + 3 and   syson == true){  //if humidity is 3% above setpoint
271    Serial.println("humidifier   OFF, fan ON");
272    digitalWrite(humidifier, HIGH);  //turn on fan
273    digitalWrite(fan,   LOW);
274  }
275  else{
276    Serial.println("all off");  //if humidity is within   3% of setpoint
277    digitalWrite(humidifier, HIGH);  //turn both off
278    digitalWrite(fan,   HIGH);
279  }
280  //delay(700);  //un-comment for serial debugging
281
282  Serial.print("setpoint   = ");
283  Serial.println(setpoint);
284
285  //delay(700);  //un-comment for serial   debugging
286}
287
288/*  WIRING DIAGRAMS
289 https://66.media.tumblr.com/98426b566744beacdd42bc0221092b76/tumblr_pvr0u8kvZy1yrmjh9o1_1280.png
290   */

//HUMIDITY CONTROLLER 1.1
//written for NANO

//controls and   displays relative humidity
//sesnor used is DHT11
//uses active-low relay   module to control live lines for 2 standard electrical outlets
//uses i2c lcd   to display humidity and humidity setting
//turns display off during inactivity
//setting   is adjustable from 10%-90% using 2 buttons
//backlight of LCD is controlled by   pin 4, connected to top LED jumper pin on i2c backpack
//serial communications   to monitor to ensure all code is working.

//added: "system off" function   - allows both outlets to be turned off

// █ G █ L █ O █ B █ A █ L █ S █
#include   <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <dht.h>

// set the   LCD address to 0x27 for a 16 chars and 2 line display
LiquidCrystal_I2C lcd(0x27,   16, 2);  

dht DHT;

#define DHT11_PIN A2

//buttons and variables   to adjust calibration
int calupbtn = A0;
int calup;
int caldownbtn = A1;
int   caldown;

//i2c PINS A4, A5

//pin for turning on humidifier relay
int   humidifier = 3;
//pin for turning on the fan relay
int fan = 2;
//pin for   turning on LCD backlights
int lcdlight = 4;

//calibration variable
int   setpoint = 50;  //feedback setpoint.  
bool calstate = false;  //enables calibration   adjustments only when LCD is ON.

//backlight timing variables
int displtime   = 12000;  //amount of time the display is to be on before turning off
unsigned   long displtimeon;  //last recorded time display timer was reset
int calunlock   = 0;   //loop counter for unlocking calibration  

//sensor timing variables
unsigned   long lastcheck;  //last time DHT was read
long interval = 30000;      //time   between DHT readings

//system variables
bool syson = true;    //reference   for system on/off. 
byte systog = 2;       //even number toggles on, odds toggle   off
int syslock = 0;     //loop counter for unlocking system toggle

//   █ S █ E █ T █ U █ P █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █
void   setup(){

  Serial.begin(9600);  //serial communication used to ensure code   is working correctly.
  
  lcd.init();  //initialize LCD
  lcd.backlight();   //enable LCD backlight, but doesn't turn it on

  lastcheck = 0;
  digitalWrite(lcdlight,   HIGH);
  Serial.println("STARTING");
  lcd.print("   STARTING");

   //pin assignments
  pinMode(calupbtn, INPUT);
  pinMode(caldownbtn, INPUT);
   pinMode(humidifier, OUTPUT);
  pinMode(fan, OUTPUT);
  pinMode(lcdlight,   OUTPUT);
  delay(1000);

  
  //test fan
  lcd.setCursor(0,1);
   lcd.print("<FAN>     HMDFR  ");  
  digitalWrite(fan, LOW);
  digitalWrite(humidifier,   HIGH);
  delay(6000);
  //test humidifier
  lcd.setCursor(0,1);
  lcd.print("   FAN     <HMDFR> ");
  digitalWrite(fan, HIGH);
  digitalWrite(humidifier,   LOW);
  delay(6000);
  //stop startup test
  digitalWrite(humidifier, HIGH);
   digitalWrite(fan, HIGH);
  lcd.clear();

  displtimeon = millis();

   int chk = DHT.read11(DHT11_PIN);
  lastcheck = millis();

  lcd.setCursor(0,0);
   lcd.print("Humidity: ");
  lcd.setCursor(13,0);
  lcd.print(DHT.humidity);
   lcd.setCursor(15,0);
  lcd.print("%  ");
  lcd.setCursor(0,1);
  lcd.print("setting:   ");
  lcd.setCursor(13,1);
  lcd.print(setpoint);
  lcd.setCursor(15,1);
   lcd.print("%  ");
  delay(100);
}

// █ L █ O █ O █ P █ = █ = █   = █ = █ = █ = █ = █ = █ = █ = █ = █ = █ = █ = █ = █
void loop(){

  //check   calibration buttons
  calup = digitalRead(calupbtn);
  caldown = digitalRead(caldownbtn);

   if(calup == HIGH and caldown == HIGH){  //--------SYSTEM TOGGLE
    syslock   ++;
    Serial.println(syslock);
    if(syslock == 20){  //if both buttons   held down for this many loops
      systog++;
      if(systog % 2 == 1){  //--------SYSTEM   OFF
        syson = false;
        digitalWrite(fan, HIGH);
        digitalWrite(humidifier,   HIGH);
        digitalWrite(lcdlight, HIGH);
        Serial.println("SYSTEM   TURNED OFF");
        lcd.clear();
        lcd.print("   SYSTEM OFF");
         lcd.setCursor(0,1);
        lcd.print("  hold both btns");
        delay(2000);
         lcd.setCursor(0,1);
        lcd.print("  to turn on    ");
        displtimeon   = millis();
      }
      if(systog % 2 == 0){  //--------SYSTEM ON
        syson   = true;
        Serial.println("SYSTEM TURNED ON");
        digitalWrite(lcdlight,   HIGH);
        lcd.clear();
        lcd.print("   SYSTEM ON");
        delay(2000);
         lcd.clear();
        displtimeon = millis();
      }
      syslock   = 0;
    }
  }
  else(syslock = 0);
  
  //read humidity at appropriate   intervals
  if(millis() > lastcheck + interval and syson == true){  //read the   DHT humidity
    int chk = DHT.read11(DHT11_PIN);
    lastcheck = millis();
     Serial.print("DHT read = ");
    Serial.print(DHT.humidity);
    Serial.print("%");
     Serial.println(" ");
    }

  //turn on the led lights when calibration   buttons are pressed
  if(calup == HIGH xor caldown == HIGH){
    digitalWrite(lcdlight,   HIGH);
    calstate = true;
    displtimeon = millis();  //set display timer
     Serial.println("cal btn ACTIVE");
    if(syson == false){
      digitalWrite(lcdlight,   HIGH);
      lcd.clear();
      lcd.print("   SYSTEM OFF");
      lcd.setCursor(0,1);
       lcd.print("  hold both btns");
      delay(3000);
      lcd.setCursor(0,1);
       lcd.print("  to turn on    ");
      displtimeon = millis();
    }
   }

  if(calstate == true and syson == true){  //--------DISPLAY ROUTINE
     Serial.println("printing display");
    //display variables on LCD
     lcd.setCursor(0,0);
    lcd.print("Humidity: ");
    lcd.setCursor(13,0);
     lcd.print(DHT.humidity);
    lcd.setCursor(15,0);
    lcd.print("%  ");
     lcd.setCursor(0,1);
    lcd.print("setting: ");
    lcd.setCursor(13,1);
     lcd.print(setpoint);
    lcd.setCursor(15,1);
    lcd.print("%  ");
     delay(100);

    calunlock ++;  
    //keeps calibration locked until   display cycles 5 times after initially turned on
    //prevents adjustments on   initial button press.
  }

//--------CALIBRATION ADJUSTMENTS
  if(calup   == HIGH and caldown == LOW and calstate == true and syson == true){ 
    if(setpoint   < 90 and calunlock > 5){ 
      setpoint = setpoint + 5;  //increase setpoint   
      Serial.println("adj setpoint up");
    }
    Serial.println(setpoint);
     delay(100);
    displtimeon = millis();     //reset backlight timeout
   }

  if(caldown == HIGH and calup == LOW and calstate == true and syson   == true){
    if(setpoint > 10 and calunlock > 5){
      setpoint = setpoint   - 5;  //decrease setpoint
      Serial.println("adj setpoint dn");
      }
     Serial.println(setpoint);
    delay(100);  
    displtimeon = millis();      //reset backlight timeout
  }

  if(millis() > displtimeon + displtime){   //-----------------BACKLIGHT TIMEOUT
    digitalWrite(lcdlight, LOW); //turn   off the screen
    calstate = false;
    Serial.println("displ + backlights   off");
    lcd.clear();
    calunlock = 0;  //lock calibration
  }

   if(millis() < lastcheck){
    lastcheck = millis();  //reset timers in a millisecond   rollover
  }

                                      //--------SETPOINT   ERROR PROCEDURE
  if(setpoint > 91 or setpoint < 9){  //in case setpoint is ever   out of bounds
    Serial.println("O/B ERROR");
    digitalWrite(lcdlight,   HIGH);
    lcd.clear();
    lcd.print("O/B ERROR");  //display error message   on lcd
    lcd.setCursor(0,1);
    lcd.print("RESETTING");
    delay(1000);
     for(int count = 9; count >= 0; count = count - 1){
      lcd.setCursor(15,1);
       lcd.print(count);     //count down from 10
      delay(1000);
    }
     setpoint = 50;        //reset setpoint at 50.
    displtimeon = millis();
   }

  //turn on humidifier relay if below setpoint  --------RELAY CONTROL
   //RELAY MODULE IS ACTIVE LOW
  if(DHT.humidity <= setpoint - 3 and syson ==   true){  //if humidity is 3% lower than setpoint
    Serial.println("humidifier   ON, fan OFF");  
    digitalWrite(humidifier, LOW);  //turn on humidifier
     digitalWrite(fan, HIGH);
  }
  else if(DHT.humidity >= setpoint + 3 and   syson == true){  //if humidity is 3% above setpoint
    Serial.println("humidifier   OFF, fan ON");
    digitalWrite(humidifier, HIGH);  //turn on fan
    digitalWrite(fan,   LOW);
  }
  else{
    Serial.println("all off");  //if humidity is within   3% of setpoint
    digitalWrite(humidifier, HIGH);  //turn both off
    digitalWrite(fan,   HIGH);
  }
  //delay(700);  //un-comment for serial debugging

  Serial.print("setpoint   = ");
  Serial.println(setpoint);

  //delay(700);  //un-comment for serial   debugging
}

/*  WIRING DIAGRAMS
 https://66.media.tumblr.com/98426b566744beacdd42bc0221092b76/tumblr_pvr0u8kvZy1yrmjh9o1_1280.png
   */

Humidity controller code

c_cpp

code for operating the humidity controller

1//HUMIDITY CONTROLLER 1.1
2//written for NANO
3
4//controls and  displays relative humidity
5//sesnor used is DHT11
6//uses active-low relay  module to control live lines for 2 standard electrical outlets
7//uses i2c lcd  to display humidity and humidity setting
8//turns display off during inactivity
9//setting  is adjustable from 10%-90% using 2 buttons
10//backlight of LCD is controlled by  pin 4, connected to top LED jumper pin on i2c backpack
11//serial communications  to monitor to ensure all code is working.
12
13//added: "system off" function  - allows both outlets to be turned off
14
15// █ G █ L █ O █ B █ A █ L █ S █
16#include  <Wire.h>
17#include <LiquidCrystal_I2C.h>
18#include <dht.h>
19
20// set the  LCD address to 0x27 for a 16 chars and 2 line display
21LiquidCrystal_I2C lcd(0x27,  16, 2);  
22
23dht DHT;
24
25#define DHT11_PIN A2
26
27//buttons and variables  to adjust calibration
28int calupbtn = A0;
29int calup;
30int caldownbtn = A1;
31int  caldown;
32
33//i2c PINS A4, A5
34
35//pin for turning on humidifier relay
36int  humidifier = 3;
37//pin for turning on the fan relay
38int fan = 2;
39//pin for  turning on LCD backlights
40int lcdlight = 4;
41
42//calibration variable
43int  setpoint = 50;  //feedback setpoint.  
44bool calstate = false;  //enables calibration  adjustments only when LCD is ON.
45
46//backlight timing variables
47int displtime  = 12000;  //amount of time the display is to be on before turning off
48unsigned  long displtimeon;  //last recorded time display timer was reset
49int calunlock  = 0;   //loop counter for unlocking calibration  
50
51//sensor timing variables
52unsigned  long lastcheck;  //last time DHT was read
53long interval = 30000;      //time  between DHT readings
54
55//system variables
56bool syson = true;    //reference  for system on/off. 
57byte systog = 2;       //even number toggles on, odds toggle  off
58int syslock = 0;     //loop counter for unlocking system toggle
59
60//  █ S █ E █ T █ U █ P █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █
61void  setup(){
62
63  Serial.begin(9600);  //serial communication used to ensure code  is working correctly.
64  
65  lcd.init();  //initialize LCD
66  lcd.backlight();  //enable LCD backlight, but doesn't turn it on
67
68  lastcheck = 0;
69  digitalWrite(lcdlight,  HIGH);
70  Serial.println("STARTING");
71  lcd.print("   STARTING");
72
73  //pin assignments
74  pinMode(calupbtn, INPUT);
75  pinMode(caldownbtn, INPUT);
76  pinMode(humidifier, OUTPUT);
77  pinMode(fan, OUTPUT);
78  pinMode(lcdlight,  OUTPUT);
79  delay(1000);
80
81  
82  //test fan
83  lcd.setCursor(0,1);
84  lcd.print("<FAN>     HMDFR  ");  
85  digitalWrite(fan, LOW);
86  digitalWrite(humidifier,  HIGH);
87  delay(6000);
88  //test humidifier
89  lcd.setCursor(0,1);
90  lcd.print("  FAN     <HMDFR> ");
91  digitalWrite(fan, HIGH);
92  digitalWrite(humidifier,  LOW);
93  delay(6000);
94  //stop startup test
95  digitalWrite(humidifier, HIGH);
96  digitalWrite(fan, HIGH);
97  lcd.clear();
98
99  displtimeon = millis();
100
101  int chk = DHT.read11(DHT11_PIN);
102  lastcheck = millis();
103
104  lcd.setCursor(0,0);
105  lcd.print("Humidity: ");
106  lcd.setCursor(13,0);
107  lcd.print(DHT.humidity);
108  lcd.setCursor(15,0);
109  lcd.print("%  ");
110  lcd.setCursor(0,1);
111  lcd.print("setting:  ");
112  lcd.setCursor(13,1);
113  lcd.print(setpoint);
114  lcd.setCursor(15,1);
115  lcd.print("%  ");
116  delay(100);
117}
118
119// █ L █ O █ O █ P █ = █ = █  = █ = █ = █ = █ = █ = █ = █ = █ = █ = █ = █ = █ = █
120void loop(){
121
122  //check  calibration buttons
123  calup = digitalRead(calupbtn);
124  caldown = digitalRead(caldownbtn);
125
126  if(calup == HIGH and caldown == HIGH){  //--------SYSTEM TOGGLE
127    syslock  ++;
128    Serial.println(syslock);
129    if(syslock == 20){  //if both buttons  held down for this many loops
130      systog++;
131      if(systog % 2 == 1){  //--------SYSTEM  OFF
132        syson = false;
133        digitalWrite(fan, HIGH);
134        digitalWrite(humidifier,  HIGH);
135        digitalWrite(lcdlight, HIGH);
136        Serial.println("SYSTEM  TURNED OFF");
137        lcd.clear();
138        lcd.print("   SYSTEM OFF");
139        lcd.setCursor(0,1);
140        lcd.print("  hold both btns");
141        delay(2000);
142        lcd.setCursor(0,1);
143        lcd.print("  to turn on    ");
144        displtimeon  = millis();
145      }
146      if(systog % 2 == 0){  //--------SYSTEM ON
147        syson  = true;
148        Serial.println("SYSTEM TURNED ON");
149        digitalWrite(lcdlight,  HIGH);
150        lcd.clear();
151        lcd.print("   SYSTEM ON");
152        delay(2000);
153        lcd.clear();
154        displtimeon = millis();
155      }
156      syslock  = 0;
157    }
158  }
159  else(syslock = 0);
160  
161  //read humidity at appropriate  intervals
162  if(millis() > lastcheck + interval and syson == true){  //read the  DHT humidity
163    int chk = DHT.read11(DHT11_PIN);
164    lastcheck = millis();
165    Serial.print("DHT read = ");
166    Serial.print(DHT.humidity);
167    Serial.print("%");
168    Serial.println(" ");
169    }
170
171  //turn on the led lights when calibration  buttons are pressed
172  if(calup == HIGH xor caldown == HIGH){
173    digitalWrite(lcdlight,  HIGH);
174    calstate = true;
175    displtimeon = millis();  //set display timer
176    Serial.println("cal btn ACTIVE");
177    if(syson == false){
178      digitalWrite(lcdlight,  HIGH);
179      lcd.clear();
180      lcd.print("   SYSTEM OFF");
181      lcd.setCursor(0,1);
182      lcd.print("  hold both btns");
183      delay(3000);
184      lcd.setCursor(0,1);
185      lcd.print("  to turn on    ");
186      displtimeon = millis();
187    }
188  }
189
190  if(calstate == true and syson == true){  //--------DISPLAY ROUTINE
191    Serial.println("printing display");
192    //display variables on LCD
193    lcd.setCursor(0,0);
194    lcd.print("Humidity: ");
195    lcd.setCursor(13,0);
196    lcd.print(DHT.humidity);
197    lcd.setCursor(15,0);
198    lcd.print("%  ");
199    lcd.setCursor(0,1);
200    lcd.print("setting: ");
201    lcd.setCursor(13,1);
202    lcd.print(setpoint);
203    lcd.setCursor(15,1);
204    lcd.print("%  ");
205    delay(100);
206
207    calunlock ++;  
208    //keeps calibration locked until  display cycles 5 times after initially turned on
209    //prevents adjustments on  initial button press.
210  }
211
212//--------CALIBRATION ADJUSTMENTS
213  if(calup  == HIGH and caldown == LOW and calstate == true and syson == true){ 
214    if(setpoint  < 90 and calunlock > 5){ 
215      setpoint = setpoint + 5;  //increase setpoint  
216      Serial.println("adj setpoint up");
217    }
218    Serial.println(setpoint);
219    delay(100);
220    displtimeon = millis();     //reset backlight timeout
221  }
222
223  if(caldown == HIGH and calup == LOW and calstate == true and syson  == true){
224    if(setpoint > 10 and calunlock > 5){
225      setpoint = setpoint  - 5;  //decrease setpoint
226      Serial.println("adj setpoint dn");
227      }
228    Serial.println(setpoint);
229    delay(100);  
230    displtimeon = millis();     //reset backlight timeout
231  }
232
233  if(millis() > displtimeon + displtime){  //-----------------BACKLIGHT TIMEOUT
234    digitalWrite(lcdlight, LOW); //turn  off the screen
235    calstate = false;
236    Serial.println("displ + backlights  off");
237    lcd.clear();
238    calunlock = 0;  //lock calibration
239  }
240
241  if(millis() < lastcheck){
242    lastcheck = millis();  //reset timers in a millisecond  rollover
243  }
244
245                                      //--------SETPOINT  ERROR PROCEDURE
246  if(setpoint > 91 or setpoint < 9){  //in case setpoint is ever  out of bounds
247    Serial.println("O/B ERROR");
248    digitalWrite(lcdlight,  HIGH);
249    lcd.clear();
250    lcd.print("O/B ERROR");  //display error message  on lcd
251    lcd.setCursor(0,1);
252    lcd.print("RESETTING");
253    delay(1000);
254    for(int count = 9; count >= 0; count = count - 1){
255      lcd.setCursor(15,1);
256      lcd.print(count);     //count down from 10
257      delay(1000);
258    }
259    setpoint = 50;        //reset setpoint at 50.
260    displtimeon = millis();
261  }
262
263  //turn on humidifier relay if below setpoint  --------RELAY CONTROL
264  //RELAY MODULE IS ACTIVE LOW
265  if(DHT.humidity <= setpoint - 3 and syson ==  true){  //if humidity is 3% lower than setpoint
266    Serial.println("humidifier  ON, fan OFF");  
267    digitalWrite(humidifier, LOW);  //turn on humidifier
268    digitalWrite(fan, HIGH);
269  }
270  else if(DHT.humidity >= setpoint + 3 and  syson == true){  //if humidity is 3% above setpoint
271    Serial.println("humidifier  OFF, fan ON");
272    digitalWrite(humidifier, HIGH);  //turn on fan
273    digitalWrite(fan,  LOW);
274  }
275  else{
276    Serial.println("all off");  //if humidity is within  3% of setpoint
277    digitalWrite(humidifier, HIGH);  //turn both off
278    digitalWrite(fan,  HIGH);
279  }
280  //delay(700);  //un-comment for serial debugging
281
282  Serial.print("setpoint  = ");
283  Serial.println(setpoint);
284
285  //delay(700);  //un-comment for serial  debugging
286}
287
288/*  WIRING DIAGRAMS
289 https://66.media.tumblr.com/98426b566744beacdd42bc0221092b76/tumblr_pvr0u8kvZy1yrmjh9o1_1280.png
290  */

//HUMIDITY CONTROLLER 1.1
//written for NANO

//controls and  displays relative humidity
//sesnor used is DHT11
//uses active-low relay  module to control live lines for 2 standard electrical outlets
//uses i2c lcd  to display humidity and humidity setting
//turns display off during inactivity
//setting  is adjustable from 10%-90% using 2 buttons
//backlight of LCD is controlled by  pin 4, connected to top LED jumper pin on i2c backpack
//serial communications  to monitor to ensure all code is working.

//added: "system off" function  - allows both outlets to be turned off

// █ G █ L █ O █ B █ A █ L █ S █
#include  <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <dht.h>

// set the  LCD address to 0x27 for a 16 chars and 2 line display
LiquidCrystal_I2C lcd(0x27,  16, 2);  

dht DHT;

#define DHT11_PIN A2

//buttons and variables  to adjust calibration
int calupbtn = A0;
int calup;
int caldownbtn = A1;
int  caldown;

//i2c PINS A4, A5

//pin for turning on humidifier relay
int  humidifier = 3;
//pin for turning on the fan relay
int fan = 2;
//pin for  turning on LCD backlights
int lcdlight = 4;

//calibration variable
int  setpoint = 50;  //feedback setpoint.  
bool calstate = false;  //enables calibration  adjustments only when LCD is ON.

//backlight timing variables
int displtime  = 12000;  //amount of time the display is to be on before turning off
unsigned  long displtimeon;  //last recorded time display timer was reset
int calunlock  = 0;   //loop counter for unlocking calibration  

//sensor timing variables
unsigned  long lastcheck;  //last time DHT was read
long interval = 30000;      //time  between DHT readings

//system variables
bool syson = true;    //reference  for system on/off. 
byte systog = 2;       //even number toggles on, odds toggle  off
int syslock = 0;     //loop counter for unlocking system toggle

//  █ S █ E █ T █ U █ P █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █ + █
void  setup(){

  Serial.begin(9600);  //serial communication used to ensure code  is working correctly.
  
  lcd.init();  //initialize LCD
  lcd.backlight();  //enable LCD backlight, but doesn't turn it on

  lastcheck = 0;
  digitalWrite(lcdlight,  HIGH);
  Serial.println("STARTING");
  lcd.print("   STARTING");

  //pin assignments
  pinMode(calupbtn, INPUT);
  pinMode(caldownbtn, INPUT);
  pinMode(humidifier, OUTPUT);
  pinMode(fan, OUTPUT);
  pinMode(lcdlight,  OUTPUT);
  delay(1000);

  
  //test fan
  lcd.setCursor(0,1);
  lcd.print("<FAN>     HMDFR  ");  
  digitalWrite(fan, LOW);
  digitalWrite(humidifier,  HIGH);
  delay(6000);
  //test humidifier
  lcd.setCursor(0,1);
  lcd.print("  FAN     <HMDFR> ");
  digitalWrite(fan, HIGH);
  digitalWrite(humidifier,  LOW);
  delay(6000);
  //stop startup test
  digitalWrite(humidifier, HIGH);
  digitalWrite(fan, HIGH);
  lcd.clear();

  displtimeon = millis();

  int chk = DHT.read11(DHT11_PIN);
  lastcheck = millis();

  lcd.setCursor(0,0);
  lcd.print("Humidity: ");
  lcd.setCursor(13,0);
  lcd.print(DHT.humidity);
  lcd.setCursor(15,0);
  lcd.print("%  ");
  lcd.setCursor(0,1);
  lcd.print("setting:  ");
  lcd.setCursor(13,1);
  lcd.print(setpoint);
  lcd.setCursor(15,1);
  lcd.print("%  ");
  delay(100);
}

// █ L █ O █ O █ P █ = █ = █  = █ = █ = █ = █ = █ = █ = █ = █ = █ = █ = █ = █ = █
void loop(){

  //check  calibration buttons
  calup = digitalRead(calupbtn);
  caldown = digitalRead(caldownbtn);

  if(calup == HIGH and caldown == HIGH){  //--------SYSTEM TOGGLE
    syslock  ++;
    Serial.println(syslock);
    if(syslock == 20){  //if both buttons  held down for this many loops
      systog++;
      if(systog % 2 == 1){  //--------SYSTEM  OFF
        syson = false;
        digitalWrite(fan, HIGH);
        digitalWrite(humidifier,  HIGH);
        digitalWrite(lcdlight, HIGH);
        Serial.println("SYSTEM  TURNED OFF");
        lcd.clear();
        lcd.print("   SYSTEM OFF");
        lcd.setCursor(0,1);
        lcd.print("  hold both btns");
        delay(2000);
        lcd.setCursor(0,1);
        lcd.print("  to turn on    ");
        displtimeon  = millis();
      }
      if(systog % 2 == 0){  //--------SYSTEM ON
        syson  = true;
        Serial.println("SYSTEM TURNED ON");
        digitalWrite(lcdlight,  HIGH);
        lcd.clear();
        lcd.print("   SYSTEM ON");
        delay(2000);
        lcd.clear();
        displtimeon = millis();
      }
      syslock  = 0;
    }
  }
  else(syslock = 0);
  
  //read humidity at appropriate  intervals
  if(millis() > lastcheck + interval and syson == true){  //read the  DHT humidity
    int chk = DHT.read11(DHT11_PIN);
    lastcheck = millis();
    Serial.print("DHT read = ");
    Serial.print(DHT.humidity);
    Serial.print("%");
    Serial.println(" ");
    }

  //turn on the led lights when calibration  buttons are pressed
  if(calup == HIGH xor caldown == HIGH){
    digitalWrite(lcdlight,  HIGH);
    calstate = true;
    displtimeon = millis();  //set display timer
    Serial.println("cal btn ACTIVE");
    if(syson == false){
      digitalWrite(lcdlight,  HIGH);
      lcd.clear();
      lcd.print("   SYSTEM OFF");
      lcd.setCursor(0,1);
      lcd.print("  hold both btns");
      delay(3000);
      lcd.setCursor(0,1);
      lcd.print("  to turn on    ");
      displtimeon = millis();
    }
  }

  if(calstate == true and syson == true){  //--------DISPLAY ROUTINE
    Serial.println("printing display");
    //display variables on LCD
    lcd.setCursor(0,0);
    lcd.print("Humidity: ");
    lcd.setCursor(13,0);
    lcd.print(DHT.humidity);
    lcd.setCursor(15,0);
    lcd.print("%  ");
    lcd.setCursor(0,1);
    lcd.print("setting: ");
    lcd.setCursor(13,1);
    lcd.print(setpoint);
    lcd.setCursor(15,1);
    lcd.print("%  ");
    delay(100);

    calunlock ++;  
    //keeps calibration locked until  display cycles 5 times after initially turned on
    //prevents adjustments on  initial button press.
  }

//--------CALIBRATION ADJUSTMENTS
  if(calup  == HIGH and caldown == LOW and calstate == true and syson == true){ 
    if(setpoint  < 90 and calunlock > 5){ 
      setpoint = setpoint + 5;  //increase setpoint  
      Serial.println("adj setpoint up");
    }
    Serial.println(setpoint);
    delay(100);
    displtimeon = millis();     //reset backlight timeout
  }

  if(caldown == HIGH and calup == LOW and calstate == true and syson  == true){
    if(setpoint > 10 and calunlock > 5){
      setpoint = setpoint  - 5;  //decrease setpoint
      Serial.println("adj setpoint dn");
      }
    Serial.println(setpoint);
    delay(100);  
    displtimeon = millis();     //reset backlight timeout
  }

  if(millis() > displtimeon + displtime){  //-----------------BACKLIGHT TIMEOUT
    digitalWrite(lcdlight, LOW); //turn  off the screen
    calstate = false;
    Serial.println("displ + backlights  off");
    lcd.clear();
    calunlock = 0;  //lock calibration
  }

  if(millis() < lastcheck){
    lastcheck = millis();  //reset timers in a millisecond  rollover
  }

                                      //--------SETPOINT  ERROR PROCEDURE
  if(setpoint > 91 or setpoint < 9){  //in case setpoint is ever  out of bounds
    Serial.println("O/B ERROR");
    digitalWrite(lcdlight,  HIGH);
    lcd.clear();
    lcd.print("O/B ERROR");  //display error message  on lcd
    lcd.setCursor(0,1);
    lcd.print("RESETTING");
    delay(1000);
    for(int count = 9; count >= 0; count = count - 1){
      lcd.setCursor(15,1);
      lcd.print(count);     //count down from 10
      delay(1000);
    }
    setpoint = 50;        //reset setpoint at 50.
    displtimeon = millis();
  }

  //turn on humidifier relay if below setpoint  --------RELAY CONTROL
  //RELAY MODULE IS ACTIVE LOW
  if(DHT.humidity <= setpoint - 3 and syson ==  true){  //if humidity is 3% lower than setpoint
    Serial.println("humidifier  ON, fan OFF");  
    digitalWrite(humidifier, LOW);  //turn on humidifier
    digitalWrite(fan, HIGH);
  }
  else if(DHT.humidity >= setpoint + 3 and  syson == true){  //if humidity is 3% above setpoint
    Serial.println("humidifier  OFF, fan ON");
    digitalWrite(humidifier, HIGH);  //turn on fan
    digitalWrite(fan,  LOW);
  }
  else{
    Serial.println("all off");  //if humidity is within  3% of setpoint
    digitalWrite(humidifier, HIGH);  //turn both off
    digitalWrite(fan,  HIGH);
  }
  //delay(700);  //un-comment for serial debugging

  Serial.print("setpoint  = ");
  Serial.println(setpoint);

  //delay(700);  //un-comment for serial  debugging
}

/*  WIRING DIAGRAMS
 https://66.media.tumblr.com/98426b566744beacdd42bc0221092b76/tumblr_pvr0u8kvZy1yrmjh9o1_1280.png
  */

Downloadable files

wiring diagram

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