How to Use KY-025: Examples, Pinouts, and Specs

The KY-025 is a temperature and humidity sensor module manufactured by ESP32 with the part ID 13. It integrates the DHT11 sensor to provide accurate digital output for temperature and humidity measurements. This module is widely used in environmental monitoring, weather stations, and home automation systems due to its simplicity and reliability.

• Weather monitoring systems
• Home automation for climate control
• Greenhouse environmental monitoring
• Industrial temperature and humidity tracking
• IoT-based environmental sensing projects

The KY-025 module is designed for ease of use and compatibility with microcontrollers like Arduino and ESP32. Below are its key technical details:

The KY-025 module has three pins for easy interfacing with microcontrollers. Below is the pinout:

The KY-025 module is straightforward to use in a circuit. Follow the steps below to integrate it into your project:

1. Power the Module: Connect the VCC pin to the 3.3V or 5V power supply of your microcontroller and the GND pin to the ground.
2. Connect the Output Pin: Attach the OUT pin to a digital input pin on your microcontroller.
3. Use a Pull-Up Resistor: The OUT pin requires a pull-up resistor (typically 10kΩ) to function correctly. Connect the resistor between the OUT pin and the VCC pin.

Below is an example Arduino sketch to read temperature and humidity data from the KY-025 module:

#include <DHT.h>

// Define the pin connected to the KY-025 OUT pin
#define DHTPIN 2

// Define the DHT sensor type (DHT11 for KY-025)
#define DHTTYPE DHT11

// Initialize the DHT sensor
DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600); // Start serial communication at 9600 baud
  dht.begin();        // Initialize the DHT sensor
  Serial.println("KY-025 Temperature and Humidity Sensor Test");
}

void loop() {
  delay(2000); // Wait 2 seconds between readings

  // Read temperature and humidity
  float humidity = dht.readHumidity();
  float temperature = dht.readTemperature();

  // Check if the readings are valid
  if (isnan(humidity) || isnan(temperature)) {
    Serial.println("Failed to read from KY-025 sensor!");
    return;
  }

  // Print the readings to the Serial Monitor
  Serial.print("Humidity: ");
  Serial.print(humidity);
  Serial.print(" %\t");
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.println(" °C");
}

• Power Supply: Ensure the module is powered within its operating voltage range (3.3V - 5V).
• Pull-Up Resistor: Always use a pull-up resistor on the OUT pin to ensure proper communication.
• Environmental Factors: Avoid placing the sensor in environments with condensation or extreme temperatures, as this may affect accuracy.
• Data Refresh Rate: The DHT11 sensor has a refresh rate of 1Hz (1 reading per second). Avoid polling the sensor more frequently.

1. No Output or Incorrect Readings:

   • Ensure the OUT pin is connected to the correct digital input pin on the microcontroller.
   • Verify the pull-up resistor is properly connected between the OUT and VCC pins.
   • Check the power supply voltage (3.3V - 5V) to ensure it is within the operating range.

2. "Failed to read from KY-025 sensor!" Error:

   • This error occurs when the sensor does not respond. Double-check the wiring and ensure the sensor is not damaged.
   • Ensure the DHT library is correctly installed in your Arduino IDE.

3. Inconsistent Readings:

   • Place the sensor in a stable environment to avoid rapid changes in temperature or humidity.
   • Ensure the sensor is not exposed to direct sunlight or strong airflow, as these can cause fluctuations.

Q: Can the KY-025 module be used outdoors?
A: The KY-025 is not waterproof or weatherproof. For outdoor use, it must be placed in a protective enclosure to shield it from moisture and extreme conditions.

Q: What is the maximum cable length for the KY-025?
A: The maximum cable length depends on the pull-up resistor value and the environment. Typically, a cable length of up to 20 meters is supported with a 10kΩ pull-up resistor.

Q: Can the KY-025 be used with a 3.3V microcontroller like ESP32?
A: Yes, the KY-025 is compatible with 3.3V microcontrollers. Ensure the VCC pin is connected to a 3.3V power source.

By following this documentation, you can effectively integrate the KY-025 module into your projects for reliable temperature and humidity monitoring.