Humidity Controller

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

Aug 8, 2019

•

22169 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

Comments

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auro_auro

3 months ago

Thanks for sharing this project. I'm a student of electronic engineering. I'm really interested in learning more from it. I was wondering if it would be possible for me to take a look at your PCB schematic diagram? It would be of great help for my studies.

Anonymous user

2 years ago

Hey , i install dht.h library but i see always dht.h: No such file or directory

Anonymous user

2 years ago

Will try this fall. Im in engineering school and not only have music instruments to take care of, i think this is brilliant! Please share other ideas ....

basssman72

4 years ago

Will try this fall. Im in engineering school and not only have music instruments to take care of, i think this is brilliant! Please share other ideas ....

radiogareth

5 years ago

Thanks for sharing this project - just what I need to look after my mushroom growing cabinet :-) It won't compile in 1.81, I'm getting three errors....first error in the listing seems to be lower case on line 18 #include <dht.h> then on compiling it stops here on line 23 with 'dht does not name a type' (fair enough maybe, so changed for DHT DHT_sens(10, DHT11); from a listing that DOES work. Its a type DHT11 and its on digital pin 10. Then it stops on line 270 } 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 } UNQUOTE with the message "expected primary-expression before '.' token". Not sure why really. I'm sure I've downloaded and checked the various libraries as both my LCD and DH11 work with separate test programs. Any ideas?

radiogareth

2 years ago

I've tried the listing in the on-line compiler and it fails in the same manner and same messages as above. How did you get it to work?

Anonymous user

6 years ago

Hey , i install dht.h library but i see always dht.h: No such file or directory

Shaeroden

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