Soil Moisture Sensor Problems

Troubleshooting
1

So I have plugged in two soil moisture sensors to measure moisture at two different depths. The code I have is below:

    int val = 0; //Variable to store soil value
    int soil = A0; //Declare a variable for the soil moisture sensor at 25cm soil depth 
    int soilPower = D6; //Variable for Soil moisture Power
    int soil2 = A1;// Declare a variable for the second soil moisture sensor at 50cm soil depth
    int soilPower2 = D5; //Variable for the second Soil moisture sensor Power

    //Rather than powering the sensor through the V-USB or 3.3V pins, 
    //we'll use a digital pin to power the sensor. This will 
    //prevent oxidation of the sensor as it sits in the corrosive soil. 

    void setup() 
    {
    Serial.begin(9600);   // open serial over USB

    pinMode(soilPower, OUTPUT); //Set D6 as an OUTPUT
    digitalWrite(soilPower, LOW); //Set to LOW so no power is flowing through the sensor
    pinMode(soilPower2, OUTPUT); //Set D5 as an OUTPUT
    digitalWrite(soilPower2, LOW); //Set to LOW so no power is flowing through the sensor

    //This line creates a variable that is exposed through the cloud.
    //You can request its value using a variety of methods
    Particle.variable("soil", &val, INT);
    Particle.variable("soil2", &val, INT);
    }

    void loop() 
    {
    Serial.print("Soil Moisture Sensor = ");    
    //get soil moisture value from the function below and print it
    Serial.println(readSoil());

    delay(1000);//take a reading every second
    }
    //This is a function used to get the soil moisture content
    int readSoil()
    {
        digitalWrite(soilPower, HIGH); //turn D6 "On"
        delay(10); //wait 10 milliseconds 
        val = analogRead(soil);
        digitalWrite(soilPower, LOW); //turn D6 "Off"
        return val;
        
        digitalWrite(soilPower2, HIGH); //turn D5 "On"
        delay(10); //wait 10 milliseconds 
        val = analogRead(soil2);
        digitalWrite(soilPower2, LOW); //turn D5 "Off"
        return val;
        
    }

So I have power running through the first sensor module but not the second? Any help would be greatly appreciated!

Thanks,

Julian

2

First, it would be good for you to state what your actual problem is. What result does this code give you vs. what you expect? One problem I see right off is that you’re returning val for soil, which causes that function to end; the part of that function that reads the second sensor is never executed. A second problem is that you’ve assigned the same variable, val, to both Particle.variables; you need to have two variables, one for each sensor (also, you should read the docs on Particle.variable, and update your code to the current syntax).

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3

add

int val2 = 0; //Variable to store soil value

change

Particle.variable("soil2", &val2, INT);

 digitalWrite(soilPower2, HIGH); //turn D5 "On"
 delay(10); //wait 10 milliseconds 
 val2 = analogRead(soil2);
 digitalWrite(soilPower2, LOW); //turn D5 "Off"
 return val2;

If you like you can check my project like this:

4

So don't

but

Particle.variable("soil2", val2);
6

Thanks for the replies, I’m still having problems trying to get power to the second module from the digital output of my electron

int val1 = 0;
int val2 = 0;
int soil1 = A0;
int soilPower1 = D0;
int soil2 = A1;
int soilPower2 = D1;

void setup() {
  Serial.begin(9600);

  pinMode(soilPower1, OUTPUT);
  digitalWrite(soilPower1, LOW);
  pinMode(soilPower2, OUTPUT);
  digitalWrite(soilPower2, LOW);
  
  Particle.variable("soil1", val1);
  Particle.variable("soil2", val2);
}

void loop() {
  Serial.print("Soil Moisture = ");
  Serial.println(readSoil());
}
int readSoil()
{
  digitalWrite(soilPower1, HIGH);//turn D0 "On"
  delay(1000);
  val1 = analogRead(soil1);
  digitalWrite(soilPower1, LOW);//turn D0 "Off"
  return val1;
  
  digitalWrite(soilPower2, HIGH);//turn D1 "On"
  delay(1000);
  val2 = analogRead(soil2);
  digitalWrite(soilPower2, LOW);//turn D1 "Off"
  return val2;
}

Thanks again for your help

7

@jrbierring, as @Ric pointed out, your code does a return val1; which ENDS THE FUNCTION. The code following the return statement NEVER GETS EXECUTED. I am putting text in caps because you seem to have missed this.

Since you declare val1 and val2 as globals, there is no need to declare your readSoil() function as returning an int. Instead, make it void and remove the return statements from the function. Then in loop() call the function and (as a separate command), Serial.print() both val1 and val2 since you know they were both updated.

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