Soil sensor with Arduino in Analog mode

Here we are going to interface a Soil sensor with Arduino (moisture sensor FC-28 ). This sensor measures the moistness content of water in the soil and gives us the moisture or dryness level as output. The sensor is prepared with both analog and digital outputs, so it can be used in both analog mode and digital mode. We will see interfacing in both modes of the sensor. But here in Analog Mode.

CLICK HERE FOR SOIL SENSOR WITH ARDUINO IN DIGITAL MODE DIGITAL 

WORKING OF SOIL MOISTURE SENSOR

The soil moisture sensor consists of two probes that are immersed in soil to measure the moistness content of water. Current passes from one probe to reach another probe through/via soil and then it gets the resistance value which is then calibrated and we get moisture level.

When there is more water (moisture level will be higher), the soil will conduct more electricity which means that there will be less resistance.

Dry soil conducts electricity poorly, so when there will be less water (moisture level will be lower), then the soil will conduct less electricity which means that there will be more resistance.

As soil moisture sensor can be used in both modes analog and digital. Let first connect it in Analog mode and then we will use it in Digital mode.

PINOUT – SOIL MOISTURE SENSOR

The soil Moisture sensor FC-28 has four pins

• VCC: For power
• A0: Analog output
• D0: Digital output
• GND: Ground

The Module also contains a potentiometer (variable resistor) which is used to set the threshold value and then this threshold value will be compared by the LM393 comparator. The output LED will light up and turn off according to this threshold value.

SOIL SENSOR WITH ARDUINO – IN ANALOG MODE

REQUIRED HARDWARE

CIRCUIT DIAGRAM

CONNECTION TABLE

MOISTURE SENSOR ARDUINO CODE IN ANALOG MODE

int sensor_pin = A0;
int output_value ;

void setup() {
  Serial.begin(9600);
  Serial.println("Reading From the Sensor ...");
  delay(2000);
}

void loop() {
  output_value = analogRead(sensor_pin);
  delay(200);

  //output_value = map(output_value, inputLow, inputHigh, outputLow, outputHigh);
  output_value = map(output_value, 0, 1023 , 10, 550);
  output_value = map(output_value, 550, 10, 0, 100);

  Serial.print("Moisture : ");
  Serial.print(output_value);
  Serial.println("%");
  delay(1000);
}

CODE EXPLANATION

//output_value = map(output_value, inputLow, inputHigh, outputLow, outputHigh);

/*

map function gives us some mathematical computing and returns a value. Computations like assign input range and map them to take output in other ranges. For example, I want to map numbers of a student into percentage. If the maximum number can be 1000 then its input range is 0-1000 and percentage will be the output so its range will be 0-100.

Map function requires 5 parameters.

1^st variable which value to be computes, here number

2^nd variable lower bound of input range i.e. 0 (numbers 0-1000)

3^rd variable upper bound of input range i.e. 1000 (numbers 0-1000)

4^th variable lower bound of output range i.e. 0 (percentage 0-100)

5^th variable lower bound of input range i.e. 100 (percentage 0-100)

So, if the number of a student is 400, it will give us 40 as output which we can consider as a percentage.

*/

/*

As we are using analog mode input range will be 0 – 1023 and its output range will be the moisture sensor data which can be from 10-550 (wetness to dryness, 550 is 100% dryness or 0% moisture and 10 is 0% dryness or 100% moisture)

*/

/*

After doing this we have an input range of 10 to 550, now we want to convert this values in percentage moisture so this time we’ll map input 550-10 (we can map in reverse directions well) because we want moisture content as a mapping result from 0 – 100 % not the dryness content.

*/

OUTPUT

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