Sarah Al-Mutlaq
Published

Soil Moisture Sensing

Making a plant self watering system using SparkFun's Soil Moisture Sensor

EasyFull instructions provided4,059
Soil Moisture Sensing

Things used in this project

Hardware components

SparkFun RedBoard
SparkFun RedBoard
×1
Soil Moisture Sensor
×1
Serial Enabled 16x2 LCD - Red on Black 5V
×1
JST Jumper 3 Wire Assembly
×1
DC Motor
×1
Resistor 330 ohm
Resistor 330 ohm
×1
Breadboard (generic)
Breadboard (generic)
×1
Jumper wires (generic)
Jumper wires (generic)
×1
Transistor - NPN (P2N2222A)
×1

Software apps and online services

Arduino IDE
Arduino IDE

Story

Read more

Schematics

Motor to RedBoard circuit diagram

This is how I set up the gear motor to the RedBoard
Motor%20setup bb

Code

Code

Plain text
language:c
// SparkFun Soil Moisture Sensor and Serial LCD example 2
// By Sarah Al-Mutlaq 2015
// Sketch reads sensor and desplays level and whether soil is wet or dry
// and turns on motor if dry

// Use the softwareserial library to create a new "soft" serial port
// for the display. This prevents display corruption when uploading code.
#include <SoftwareSerial.h>

// Attach the serial display's RX line to digital pin 2
SoftwareSerial mySerial(3,2); // pin 2 = TX, pin 3 = RX (unused)

// We'll be controlling the motor from pin 9.
// This must be one of the PWM-capable pins.
const int motorPin = 9;


// Here we are setting up some water thersholds that we will 
// use later. Note that you will need to change these to match
// your soil type and environment. 

int thresholdUp = 400;
int thresholdDown = 250;

// We are setting up the pin A0 on the redboard to be our sensor
// pin input:

int sensorPin = A0;


void setup(){
  pinMode(motorPin, OUTPUT); // set pin controlling the motor as an output pin
  mySerial.begin(9600); // set up serial port for 9600 baud (speed)
  delay(500); // wait for display to boot up
}

void loop(){
  // Here we are declaring a string, which are lines of words,
  // and we want DisplayWords to be the words displayed on
  // the LCD screen, which will change based on whether the soil
  // wet or dry based on our threshold values above.
  String DisplayWords;

  // We need to set up a pin to get the value that the soil 
  // moisture sensor is outputting, so sensorValue will get the
  // analog value from the sensor pin A0 on the redboard that we 
  // set up earlier.

  int sensorValue;
  sensorValue = analogRead(sensorPin);

  // move cursor to beginning of first line on LCD:
  mySerial.write(254); 
  mySerial.write(128);

  // clear display:
  mySerial.write("                "); 
  mySerial.write("                ");

  // move cursor to beginning of first line of the LCD screen:
  mySerial.write(254); 
  mySerial.write(128);

  //Write what we want to desplay on the screen:
  mySerial.write("Water Level: ");
  mySerial.print(sensorValue); //Using .print instead of .write for values

  // Now we are going to check if the water level is below a 
  // out thresholdDown value we set earlier, and if it is have 
  // words "Dry, Water it!" display one column over on the first 
  // row:

  if (sensorValue <= thresholdDown){
    // move cursor to beginning of second line on LCD:
    mySerial.write(254); 
    mySerial.write(192);

    DisplayWords = "Dry, Water it!";
    mySerial.print(DisplayWords);

    // turns the motor on at a slow speed (0 is stopped, 255 is full speed):
    analogWrite(motorPin, 75);  


  // If the value is not below our thresholdDown value we want to 
  // check if it is above our thresholdUp value, and if it is 
  // change the display words to "Wet, Leave it!":



  } else if (sensorValue >= thresholdUp){
    // move cursor to beginning of second line on LCD:
    mySerial.write(254); 
    mySerial.write(192);

    DisplayWords = "Wet, Leave it!";
    mySerial.print(DisplayWords);

    // turns the motor off (0 is stopped, 255 is full speed):
    analogWrite(motorPin, 0);

  // Otherwise if it is inbetween the two values we want it to 
  // the display it had, so if our soil was really wet and drying 
  // the words would only change to "Dry, Water it!" when it got to the lower threshold
  // (thresholdDown), but if it was dry and getting wetter the words
  // would only change to "Wet, Leave it!" when it got to the upper 
  // threshold (thresholdUp_):

  } else {
    // move cursor to beginning of second line on LCD:
    mySerial.write(254); 
    mySerial.write(192);

    mySerial.print(DisplayWords);
  }

  delay(500); //wait for half a second, so it is easier to read
}

Code

Plain text
language:c
// SparkFun Soil Moisture Sensor and Serial LCD example 1
// By Sarah Al-Mutlaq 2015
// Sketch reads sensor and desplays level and whether soil is wet or dry

// Use the softwareserial library to create a new "soft" serial port
// for the display. This prevents display corruption when uploading code.
#include <SoftwareSerial.h>

// Attach the serial display's RX line to digital pin 2
SoftwareSerial mySerial(3,2); // pin 2 = TX, pin 3 = RX (unused)


// Here we are setting up some water thersholds that we will 
// use later. Note that you will need to change these to match
// your soil type and environment. 

int thresholdUp = 400;
int thresholdDown = 250;

// We are setting up the pin A0 on the redboard to be our sensor
// pin input:

int sensorPin = A0;


void setup(){
  mySerial.begin(9600); // set up serial port for 9600 baud (speed)
  delay(500); // wait for display to boot up
}

void loop(){
  // Here we are declaring a string, which are lines of words,
  // and we want DisplayWords to be the words displayed on
  // the LCD screen, which will change based on whether the soil
  // wet or dry based on our threshold values above.
  String DisplayWords;

  // We need to set up a pin to get the value that the soil 
  // moisture sensor is outputting, so sensorValue will get the
  // analog value from the sensor pin A0 on the redboard that we 
  // set up earlier.

  int sensorValue;
  sensorValue = analogRead(sensorPin);

  // move cursor to beginning of first line on LCD:
  mySerial.write(254); 
  mySerial.write(128);

  // clear display:
  mySerial.write("                "); 
  mySerial.write("                ");

  // move cursor to beginning of first line of the LCD screen:
  mySerial.write(254); 
  mySerial.write(128);

  //Write what we want to desplay on the screen:
  mySerial.write("Water Level: ");
  mySerial.print(sensorValue); //Using .print instead of .write for values

  // Now we are going to check if the water level is below a 
  // out thresholdDown value we set earlier, and if it is have 
  // words "Dry, Water it!" display one column over on the first 
  // row:

  if (sensorValue <= thresholdDown){
    // move cursor to beginning of second line on LCD:
    mySerial.write(254); 
    mySerial.write(192);

    DisplayWords = "Dry, Water it!";
    mySerial.print(DisplayWords);

  // If the value is not below our thresholdDown value we want to 
  // check if it is above our thresholdUp value, and if it is 
  // change the display words to "Wet, Leave it!":



  } else if (sensorValue >= thresholdUp){
    // move cursor to beginning of second line on LCD:
    mySerial.write(254); 
    mySerial.write(192);

    DisplayWords = "Wet, Leave it!";
    mySerial.print(DisplayWords);

  // Otherwise if it is inbetween the two values we want it to 
  // the display it had, so if our soil was really wet and drying 
  // the words would only change to "Dry, Water it!" when it got to the lower threshold
  // (thresholdDown), but if it was dry and getting wetter the words
  // would only change to "Wet, Leave it!" when it got to the upper 
  // threshold (thresholdUp_):

  } else {
    // move cursor to beginning of second line on LCD:
    mySerial.write(254); 
    mySerial.write(192);

    mySerial.print(DisplayWords);
  }

  delay(500); //wait for half a second, so it is easier to read
}

Github

https://github.com/arduino/Arduino/tree/master/hardware/arduino/avr/libraries/SoftwareSerial

Credits

Sarah Al-Mutlaq

Sarah Al-Mutlaq

1 project • 20 followers

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