Auto Calibration Program for Capacitive Soil Moisture Sensor

1
2//You need to use a 16x2 LCD display. There are plenty of tutorials  on how to connect these to your arduino. Just make sure the pins are correct.
3
4#include  <LiquidCrystal.h>
5LiquidCrystal lcd(12, 11, 7, 6, 5, 4);
6
7
8
9int AirValue  = 600;   //This is the sensor value when completely dry.
10int WetValue = 250;  //This is the sensor value when submerged in water.
11unsigned long timeReadingWet  = 60000; //This is the time the sensor needs to reach the full wet value (in milliseconds).
12unsigned  long timeReadingAir = 10000; //This is the time the sensor needs to reach the full  air value (in milliseconds).
13byte CalibrationButton = 8; //This is the pin number  for the button (you don't need any resistors, the Arduino uses an internal one when  declared as INPUT_PULLUP (below).
14
15
16
17
18void setup() {
19
20  Serial.begin(9600);
21  
22  lcd.begin(16, 2); 
23
24  pinMode(CalibrationButton, INPUT_PULLUP); //This  is where you declare your button pin as INPUT_PULLUP.
25
26}
27
28void loop()  {
29
30
31
32
33// This is the guided program that calibrates your capacitive  soil moisture sensor. Just add it to your exising code!
34
35
36
37  if (digitalRead(CalibrationButton)  == LOW) { //when the button is pressed
38
39    lcd.setCursor(0, 0);
40    lcd.print("Let's  calibrate");
41    lcd.setCursor(0, 1);
42    lcd.print("the sensor");
43    delay(3000);
44    lcd.clear();
45
46
47    while (digitalRead(CalibrationButton)  == HIGH) { //the program waits for the user to press the button again
48
49      
50      lcd.setCursor(0, 0);
51      lcd.print("Dry sensor");
52      lcd.setCursor(0,  1);
53      lcd.print("completely B"); //the B stands for Button, it tells the  user that the button needs to be pressed to continue
54
55
56      if (digitalRead(CalibrationButton)  == LOW) { //this happens when the button is pressed again
57
58        lcd.clear();
59
60        for (unsigned long timeStartAir = millis(); (millis() - timeStartAir) <  timeReadingAir; ) { //this loop reads the sensor for timeReadingAir (defined in  the header)
61          AirValue = max(analogRead(0), AirValue);
62          lcd.setCursor(0,  0);
63          lcd.print("Calibrating");
64          lcd.setCursor(0, 1);
65          lcd.print("for air ");
66          lcd.print((timeReadingAir/1000)-(millis()  - timeStartAir)/1000); //then displays the time remaining
67          lcd.print("s  ");
68          Serial.println(AirValue);
69
70        }
71
72        lcd.clear();
73        lcd.setCursor(0, 0);
74        lcd.print("Air value");
75        lcd.setCursor(0,  1);
76        lcd.print("established: "); //then it lets the user know that the  reading was established (then prints it)
77        lcd.print(AirValue);
78        Serial.println(AirValue);
79        delay(5000);
80
81        lcd.clear();
82
83
84        while (digitalRead(CalibrationButton)  == HIGH) { //same thing but for wet
85
86
87
88          lcd.setCursor(0, 0);
89          lcd.print("Now submerge");
90          lcd.setCursor(0, 1);
91          lcd.print("in  water B");
92
93          if (digitalRead(CalibrationButton) == LOW) {
94
95            lcd.clear();
96
97            for (unsigned long timeStartWater =  millis(); (millis() - timeStartWater) < timeReadingWet; ) {
98              WetValue  = min(analogRead(0), WetValue);
99              lcd.setCursor(0, 0);
100              lcd.print("Calibrating");
101              lcd.setCursor(0, 1);
102              lcd.print("for wet ");
103              lcd.print((timeReadingWet/1000)-(millis() - timeStartWater)/1000);
104              lcd.print("s  ");
105              Serial.println(WetValue);
106
107            }
108
109            lcd.clear();
110
111            lcd.setCursor(0,  0);
112            lcd.print("Wet value");
113            lcd.setCursor(0, 1);
114            lcd.print("established: ");
115            lcd.print(WetValue);
116            Serial.println(WetValue);
117            delay(5000);
118
119            lcd.clear();
120
121            lcd.setCursor(0, 0);
122            lcd.print("Calibration");
123            lcd.setCursor(0, 1);
124            lcd.print("successful");
125
126            Serial.println(WetValue);
127            delay(5000);
128            lcd.clear();
129
130
131            return;
132
133          }
134
135
136        }
137
138
139
140      }
141
142    }
143
144  }
145
146}
147