How to Use DFRobot Capacitive Soil Moisture Sensor (V1.0): Examples, Pinouts, and Specs

The DFRobot Capacitive Soil Moisture Sensor (V1.0) is a reliable and durable sensor designed to measure the volumetric water content in soil. Unlike traditional resistive sensors, this sensor uses capacitive sensing technology, which eliminates the risk of corrosion and ensures long-term stability. It is ideal for applications such as automated irrigation systems, agricultural monitoring, and gardening projects.

• Smart irrigation systems
• Soil moisture monitoring for agriculture
• Gardening and plant care automation
• Environmental monitoring projects
• Educational and DIY electronics projects

The DFRobot Capacitive Soil Moisture Sensor (V1.0) is designed for ease of use and compatibility with microcontrollers like Arduino. Below are its key technical details:

• Operating Voltage: 3.3V to 5.5V
• Output Voltage Range: 0V to 3V (analog signal)
• Current Consumption: < 20mA
• Interface: Analog
• Dimensions: 98mm x 23mm
• Weight: 15g
• Material: Corrosion-resistant PCB

The sensor has a simple 3-pin interface for easy connection to microcontrollers. The pinout is as follows:

The DFRobot Capacitive Soil Moisture Sensor (V1.0) is straightforward to use in a circuit. Follow the steps below to integrate it into your project:

1. Power the Sensor: Connect the VCC pin to a 3.3V or 5V power source, depending on your microcontroller's operating voltage.
2. Ground the Sensor: Connect the GND pin to the ground of your microcontroller.
3. Read the Output: Connect the AOUT pin to an analog input pin on your microcontroller to read the moisture level.

• Calibration: The sensor's output voltage corresponds to soil moisture levels. You may need to calibrate the sensor for your specific soil type by taking readings in dry and saturated soil.
• Placement: Insert the sensor into the soil vertically, ensuring the sensing area is fully covered by soil for accurate readings.
• Avoid Submersion: Do not submerge the sensor in water, as it is designed for soil use only.
• Power Supply: Use a stable power source to avoid fluctuations in readings.
• Signal Filtering: If the readings are noisy, consider adding a capacitor between the AOUT pin and ground to stabilize the signal.

Below is an example of how to use the sensor with an Arduino UNO to read and display soil moisture levels:

// Define the analog pin connected to the sensor's AOUT pin
const int sensorPin = A0; 

void setup() {
  // Initialize serial communication for debugging
  Serial.begin(9600);
}

void loop() {
  // Read the analog value from the sensor
  int sensorValue = analogRead(sensorPin);

  // Map the sensor value to a percentage (0% to 100%)
  int moisturePercent = map(sensorValue, 0, 1023, 0, 100);

  // Print the moisture level to the Serial Monitor
  Serial.print("Soil Moisture: ");
  Serial.print(moisturePercent);
  Serial.println("%");

  // Wait for 1 second before taking the next reading
  delay(1000);
}

• The map() function is used to convert the raw analog reading (0-1023) into a percentage (0-100%). Adjust the mapping range if necessary based on your calibration.
• Use the Serial Monitor in the Arduino IDE to view the moisture readings in real time.

1. No Output or Incorrect Readings

   • Cause: Loose or incorrect wiring.
   • Solution: Double-check the connections to ensure the VCC, GND, and AOUT pins are properly connected.

2. Fluctuating or Noisy Readings

   • Cause: Electrical noise or unstable power supply.
   • Solution: Add a capacitor (e.g., 0.1µF) between the AOUT pin and ground to filter noise.

3. Sensor Not Responding

   • Cause: Sensor may be damaged or improperly powered.
   • Solution: Verify the power supply voltage and ensure it is within the 3.3V to 5.5V range.

4. Inconsistent Readings in Different Soils

   • Cause: Soil type and composition affect sensor output.
   • Solution: Calibrate the sensor for the specific soil type by taking reference readings in dry and wet conditions.

Q: Can this sensor be used outdoors?
A: Yes, but it should be protected from direct exposure to water and extreme weather conditions. Consider using a waterproof enclosure for outdoor projects.

Q: How do I interpret the sensor's output?
A: The sensor outputs an analog voltage that corresponds to soil moisture levels. Higher voltage indicates drier soil, while lower voltage indicates wetter soil.

Q: Can I use this sensor with a Raspberry Pi?
A: Yes, but since the Raspberry Pi lacks analog input pins, you will need an ADC (Analog-to-Digital Converter) module to read the sensor's output.

Q: How long does the sensor last?
A: The capacitive design ensures durability and resistance to corrosion, making it suitable for long-term use compared to resistive sensors.

By following this documentation, you can effectively integrate the DFRobot Capacitive Soil Moisture Sensor (V1.0) into your projects and achieve accurate soil moisture monitoring.