How to Use KY-036: Examples, Pinouts, and Specs

The KY-036 is a capacitive soil moisture sensor designed to measure the moisture content in soil. Unlike resistive soil moisture sensors, the KY-036 uses capacitive sensing, which reduces corrosion and increases the lifespan of the sensor. It outputs an analog signal that corresponds to the soil's moisture level, making it ideal for applications requiring precise and reliable moisture detection.

• Automated irrigation systems
• Smart gardening and plant care
• Agricultural monitoring systems
• Environmental monitoring projects
• DIY electronics and Arduino-based projects

The KY-036 sensor is designed for low-power, high-accuracy soil moisture detection. Below are its key technical details:

The KY-036 has three pins for interfacing with microcontrollers or other circuits. The table below describes each pin:

1. Power the Sensor: Connect the VCC pin to a 3.3V or 5V power source and the GND pin to the ground of your circuit.
2. Read the Output: Connect the AOUT pin to an analog input pin of a microcontroller (e.g., Arduino UNO). The voltage on this pin will vary based on the soil's moisture level.
3. Insert into Soil: Place the sensor's probe into the soil you wish to monitor. Ensure the sensor is inserted to a consistent depth for accurate readings.

• Avoid Submersion: The KY-036 is not waterproof. Do not submerge the entire sensor in water; only the probe should contact the soil.
• Calibration: For accurate results, calibrate the sensor by measuring the output voltage in dry and fully saturated soil.
• Power Supply: Use a stable power source to avoid fluctuations in the output signal.
• Placement: Insert the sensor in a location representative of the soil's overall moisture level. Avoid areas with standing water or extreme dryness.

Below is an example of how to use the KY-036 with an Arduino UNO to read soil moisture levels:

// Define the analog pin connected to the KY-036 AOUT pin
const int sensorPin = A0;

// Variable to store the sensor reading
int sensorValue;

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

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

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

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

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

1. No Output or Incorrect Readings:

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

2. Fluctuating Readings:

   • Cause: Unstable power supply or electrical noise.
   • Solution: Use a decoupling capacitor (e.g., 0.1µF) between VCC and GND to stabilize the power supply.

3. Sensor Corrosion:

   • Cause: Prolonged exposure to water or harsh soil conditions.
   • Solution: Ensure only the probe is in contact with the soil and avoid submerging the sensor.

4. Output Always Reads Dry or Wet:

   • Cause: Calibration not performed or sensor damaged.
   • Solution: Calibrate the sensor using known dry and wet soil samples. If the issue persists, replace the sensor.

Q: Can the KY-036 be used outdoors?
A: Yes, but it should be protected from direct exposure to water and extreme weather conditions. Use a waterproof enclosure for the electronics if necessary.

Q: How do I interpret the analog output?
A: The output voltage is proportional to the soil's moisture level. A higher voltage indicates wetter soil, while a lower voltage indicates drier soil.

Q: Can I use the KY-036 with a 3.3V microcontroller?
A: Yes, the KY-036 operates at both 3.3V and 5V, making it compatible with a wide range of microcontrollers.

Q: How often should I calibrate the sensor?
A: Calibration should be performed whenever the sensor is used in a new type of soil or after extended periods of use.