Arduino Capacitive Soil Moisture Sensor (DIY) with ESP32

1/*
2  This code for a Soil Moisture sensor and a Moist Level Indicator  has been developed and produced by Pierre Pennings (December 2018)
3  This application  can be used e.g. in automatic plant watering systems  
4  The DIY Moisture Sensor  uses 2 pieces of fondue forks
5  The DIY Moist Level Indicator is made with 5  (Neopixel) SMD5050 LEDs with WS2812B controller chips powered with 5 V
6  The  Moist Level is measured once every second (during 5 seconds) and determines the  average of 5 consecutive measurements in 5 different levels
7  The Moist Level  Indicator is set to the measured soil moisture level
8  This sketch is written  for using 1 Moisture sensor, but in the final Plantwatering project 3 different  sensors will be used
9  
10  For this Project, an ESP 32 (NodeMCU) is used with  12 Bits ADCs
11  The ESP 32 device works at 3.3 Volt levels, while the Moist Level  Indicator runs on 5 V
12  The 5 Level LEDs have been built in a separate indicator  Display (indicating 1%, 25%, 50%, 75% and 100% levels)
13  The ESP 32 is fed with  5 V power (from a 5V adaptor or 5v powerbank), it has an on-board 3.3V voltage regulator
14  The 5 indicator LEDs get the 5V supply directly from the 5 volt pin of the ESP  32 
15    
16  This code is licensed under GPL3+ license.
17*/
18
19#include  <Adafruit_NeoPixel.h>
20#define NUM_LEDS  5
21
22
23/////////////////////////////////////////////////  initialise the GPIO pins
24const int IndicatorPin = 16;                    // pin  16 sends the control data to the LED Moist Level Indicator
25const int ToneOutput1  = 25;                     // pin 25 is used for sending a 600 kHz PWM tone to the  MoistSensor1 measurement circuit
26const int freq = 600000;
27const int Channel1  = 1;
28const int resolution = 8;
29const int MoistSensor1Pin = 4;                  //  12 bits ADC pin 4 senses the voltage level of the MoistSensor1 (values 0 - 4095)
30
31int  level = 0;                                  // Variable of the Moist Level: 1%,  25%, 50%, 75%, 100%
32int Moistlevel1 = 0;                            // Variable  to store the Moist level for sensor 1 
33
34byte color_scheme[] = {
35  0, 0,  0,                  // no color/ off
36  0, 200, 0,                // green
37  100, 200, 0,              // yellow
38  250, 150, 0,              // orange
39  0, 0, 200,                // blue
40  200, 0, 0                 // red
41};
42
43Adafruit_NeoPixel  strip = Adafruit_NeoPixel(NUM_LEDS, IndicatorPin, NEO_RGB + NEO_KHZ800);
44
45///////////////////////////////////////////////////  the setup code that follows, will run once after "Power On" or after a RESET
46void  setup() {
47  Serial.begin(115200);
48  ledcSetup(Channel1, freq, resolution);         // configure the PWM functionalitites
49  ledcAttachPin(ToneOutput1, Channel1);           // attach the channel 1 to the GPIO pin 25 for generating a PWM signal  of 600kHz
50  
51  pinMode(IndicatorPin, OUTPUT);                // Initializes  the output pin for the Moist Level Indicator
52  pinMode(MoistSensor1Pin, INPUT);               // Initializes the sensor pin (4) for measuring the MoistureLevelValue1
53  
54  strip.begin();                                 // Initialize all LEDs to  "off"
55  
56  for (int t = 0; t < 5 ; t++)
57    {
58    strip.setPixelColor(t,  100, 100, 100);       // After Power On the Moist Level Indicator LEDs are tested  once
59    strip.show();                                // note that the order  of colors of the WS2812 LED strip is R,G,B 
60    delay (200);
61    strip.setPixelColor(t,  0, 0, 0);             // and back to off
62    }
63  for (int k = 4; k > -1 ;  k--)
64    {
65    strip.setPixelColor(k, 100, 100, 100);       // blink for 0,2  seconds going top down and then off
66    strip.show();
67    delay (200);
68    strip.setPixelColor(k, 0, 0, 0);             // and back to off
69    }
70}
71
72
73///////////////////////////////////////////////////  the loop code that follows, will run repeatedly until "Power Off" or a RESET
74void  loop(){
75
76   MEASUREMOISTURE1 ();                     // measure moisture level1
77   INDICATELEVEL ();
78   delay(1000);                            // wait 1 sec  to Check for new values;
79                                            //this value  is just for demonstration purposes and will in a practical application be far less  frequent
80}
81//////////////////END of LOOP////////////////////////////////////////////////////////////  
82
83/////////////////////////////////////////////////// Hereafter follows  the Function for measuring the Moisture level with MoistSensor1 (capacitive measurement)
84
85void  MEASUREMOISTURE1 ()  {
86  Moistlevel1 = 0;
87  ledcWrite(Channel1, 128);                             //  send a PWM signal of 600 kHz to pin 25 with a dutycycle of 50%
88  delay(200);                                           // allow the circuit to stabilize  
89  for (int m = 1; m < 6 ; m++)                          // take 5 consecutive measurements  in 5 seconds
90    {
91      Moistlevel1 = Moistlevel1 + analogRead(MoistSensor1Pin)  ;    // Read data from analog pin 4 and add it to MoistLevel1 variable
92      delay  (1000);
93    }
94    Moistlevel1 = Moistlevel1 / 5;                       //  Determine the average of 5 measurements 
95    
96    if (Moistlevel1 > 150 &&  Moistlevel1 < 375){
97      level = 5;                                         //  means moistlevel is 100%
98      Serial.print(" Moistlevel is 100% "); Serial.print("  Moistlevel1 = "); Serial.println (Moistlevel1);
99    }
100    if (Moistlevel1  > 375 && Moistlevel1 < 725){
101      level = 4;                                         //  means moistlevel is 75%
102      Serial.print(" Moistlevel is 75% "); Serial.print("  Moistlevel1 = "); Serial.println (Moistlevel1);
103    }
104    if (Moistlevel1  > 725 && Moistlevel1 < 1075){
105      level = 3;                                         //  means moistlevel is 50%
106      Serial.print(" Moistlevel is 50% "); Serial.print("  Moistlevel1 = "); Serial.println (Moistlevel1);
107    }
108    if (Moistlevel1  > 1075 && Moistlevel1 < 1425){
109      level = 2;                                         //  means moistlevel is 25%
110      Serial.print(" Moistlevel is 25% "); Serial.print("  Moistlevel1 = "); Serial.println (Moistlevel1);
111    }
112    if (Moistlevel1  > 1425 && Moistlevel1 < 1775){
113      level = 1;                                         //  means moistlevel is 1%
114      Serial.print(" Moistlevel is 1% "); Serial.print("  Moistlevel1 = "); Serial.println (Moistlevel1);
115    }
116  ledcWrite(Channel1,  0);                                // stop generating PWM tones at pin 25
117  }
118
119
120///////////////////////////////////////////////////  Hereafter follows the Function for Indicating the MoistureLevel (called from within  the loop)
121
122void INDICATELEVEL ()  {
123
124for (int t = 0; t < 6 ; t++)
125    {
126    strip.setPixelColor(t, 0, 0, 0);                     // turn off all  LEDs on the Moist Level Indicator
127    strip.show();                                  
128    }
129    
130int redVal, greenVal, blueVal;                          // Set  the Moist Level Indicator LED with a color defined in the Array color_scheme
131    redVal = color_scheme[level*3];
132    greenVal = color_scheme[level*3 + 1];
133    blueVal = color_scheme[level*3 + 2];
134    
135    strip.setPixelColor(level-1,  strip.Color(redVal, greenVal, blueVal) ); 
136    strip.show();
137    }
138
139