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--- capacitive_soil_moisture_sensing [2019/06/14 10:49] – created 192.168.1.179
+++ capacitive_soil_moisture_sensing [2019/08/17 17:29] (current) – 192.168.1.250
@@ Line 1: / Line 1: @@
+===== Capacitive Soil Moisture Sensing =====
-I picked up some inexpensive soil moisture monitors from Banggood.  I found a really nice youtube tutorial where the guy hooks up an arduino and an oled to sense moisture.  The readings are scalled to 4 text values: dry, damp, moist and wet.  This text is then displayed on an OLED.\\
+I picked up some inexpensive soil moisture monitors from Banggood.  I found a really nice youtube tutorial where the guy hooks up an Arduino and an oled to sense moisture.  The readings are scalled to 4 text values: dry, damp, moist and wet.  This text is then displayed on an OLED.\\
 The sketch and schematic is in the Arduino Projects directory at:
@@ Line 7: / Line 7: @@
 </code>
+The sample code is also here:\\
+<code>
+/*********************************************************************
+  This is an example for reading the analog sensor output of a
+  capacitive soil moisture probe and displaying the result on a
+x64 OLED display over the I2C bus.
+  This example requires the SSD1306 display driver by Adafruit:
+  https://github.com/adafruit/Adafruit_SSD1306
+  Video detailing the capacitive soil moisture measurement probe:
+  https://youtu.be/pdGRs7GXBeE
+*********************************************************************/
+#include <Wire.h>
+#include <Adafruit_SSD1306.h>
+#define OLED_RESET 4
+Adafruit_SSD1306 display(OLED_RESET);
+// make sure the SSD1306 driver is configured for 64 line height
+#if (SSD1306_LCDHEIGHT != 64)
+#error("Height incorrect, please fix Adafruit_SSD1306.h!");
+#endif
+const int wetProbe      = 300;   // wet readings are around 1.5v or analog input value ~300
+const int dryProbe      = 620;   // dry readings are around   3v or analog input value ~620
+// Analog Sensor Input Pin
+int sensorInput         = 0;    // soil probe is on analog input 0
+// Variables
+int validSensorReading  = 0;    // valid sensor analog reading to record
+int sensorReading;              // new sensor reading to evaluate and record or discard
+int sensorResult;               // scaled sensor data [0..3] = [wet, damp, moist, dry]
+void setup()   {
+  Serial.begin(9600);           // some debug messages will display sensor raw data
+  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);  // initialize with the I2C address of the display
+  display.clearDisplay();                     // clear the display buffer
+}
+void loop() {
+  sensorReading = analogRead(sensorInput);
+  if (abs(validSensorReading - sensorReading) > 10) {
+    validSensorReading = sensorReading;
+  }
+  Serial.print ("Old Sensor Reading: ");
+  Serial.println (validSensorReading);
+  Serial.print ("New Sensor Reading: ");
+  Serial.println (sensorReading);
+  sensorResult = map(validSensorReading, wetProbe, dryProbe, 0, 4);  // scale analog input to a smaller range for wet to dry
+  Serial.print ("Scaled Sensor Reading 0-4: ");
+  Serial.println (sensorResult);
+  Serial.println ();
+  // display the correct soil moisture level on the display
+  // lower voltages represent more wet levels
+  switch (sensorResult) {
+    case 0:
+      displayTextProbe("Wet");
+      break;
+    case 1:
+      displayTextProbe("Damp");
+      break;
+    case 2:
+      displayTextProbe("Moist");
+      break;
+    case 3:
+      displayTextProbe("Dry");
+      break;
+    case 4:    // same as case 3, due to how map works.
+      displayTextProbe("Dry");
+      break;
+  }
+  delay(500);
+}
+void displayTextProbe(const char * sensorDisplay) {
+  display.setTextSize(2);
+  display.setTextColor(WHITE);
+  display.setCursor(0, 0);
+  display.clearDisplay();
+  display.println("Soil: ");
+  display.println(sensorDisplay);
+  display.display();
+  delay(1);
+}
+</code>
+{{::soilmoisture_zrkzpdzsyp.jpg?600|}}