How to Use KY-029: Examples, Pinouts, and Specs

The KY-029 is a temperature sensor module that utilizes the LM35 temperature sensor. It provides an analog output proportional to the temperature, making it an ideal choice for temperature monitoring and control applications. The module is designed for easy integration into microcontroller-based projects, offering precise and reliable temperature readings without requiring complex calibration.

• Environmental monitoring systems
• HVAC (Heating, Ventilation, and Air Conditioning) control
• Industrial temperature monitoring
• Home automation systems
• Educational projects and prototyping

The KY-029 module is built around the LM35 temperature sensor, which outputs a voltage directly proportional to the temperature in degrees Celsius. Below are the key technical details:

The KY-029 module has three pins for easy interfacing:

1. Power the Module: Connect the VCC pin to a 5V power supply (or any voltage within the operating range) and the GND pin to the ground of your circuit.
2. Read the Output: Connect the OUT pin to an analog input pin of your microcontroller (e.g., Arduino UNO). The voltage on this pin corresponds to the temperature in degrees Celsius, with a sensitivity of 10mV/°C.
3. Convert Voltage to Temperature: Use the formula Temperature (°C) = Voltage (mV) / 10 to calculate the temperature.

• Power Supply Stability: Ensure a stable power supply to avoid fluctuations in the output voltage.
• Avoid Overheating: Do not expose the sensor to temperatures beyond its specified range (-55°C to +150°C).
• Analog-to-Digital Conversion: When using a microcontroller, ensure the ADC resolution is sufficient to capture small changes in the output voltage.
• Calibration: While the LM35 is factory-calibrated, you may perform additional calibration for higher accuracy in specific applications.

Below is an example code to read temperature data from the KY-029 module using an Arduino UNO:

// Define the analog pin connected to the KY-029 OUT pin
const int sensorPin = A0;

void setup() {
  Serial.begin(9600); // Initialize serial communication at 9600 baud
}

void loop() {
  int sensorValue = analogRead(sensorPin); // Read the analog value
  float voltage = sensorValue * (5.0 / 1023.0); // Convert to voltage
  float temperature = voltage * 100.0; // Convert voltage to temperature (°C)
  
  // Print the temperature to the Serial Monitor
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.println(" °C");
  
  delay(1000); // Wait for 1 second before the next reading
}

• The formula voltage * 100.0 is derived from the LM35's sensitivity of 10mV/°C.
• Ensure the Arduino's reference voltage is set to 5V for accurate readings.

1. No Output or Incorrect Readings:

   • Cause: Incorrect wiring or loose connections.
   • Solution: Double-check the connections, ensuring VCC, GND, and OUT are properly connected.

2. Fluctuating Temperature 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. Output Voltage Does Not Match Expected Temperature:

   • Cause: Incorrect ADC reference voltage or formula.
   • Solution: Verify the ADC reference voltage and ensure the formula used for conversion is correct.

4. Sensor Overheating:

   • Cause: Exposure to high temperatures beyond the sensor's range.
   • Solution: Ensure the sensor operates within its specified temperature range (-55°C to +150°C).

Q1: Can the KY-029 measure negative temperatures?
Yes, the LM35 sensor can measure temperatures as low as -55°C. However, for negative temperatures, the output voltage will be below 0V, which may require additional circuitry to read accurately.

Q2: Can I use the KY-029 with a 3.3V microcontroller?
Yes, the KY-029 can operate with a 3.3V power supply. However, ensure the output voltage range is compatible with the ADC input range of your microcontroller.

Q3: How do I improve the accuracy of the temperature readings?
To improve accuracy:

• Use a stable power supply.
• Place the sensor in a location with minimal airflow or temperature fluctuations.
• Perform calibration if necessary.

Q4: Is the KY-029 waterproof?
No, the KY-029 is not waterproof. For applications in humid or wet environments, consider using a waterproof housing or a different sensor designed for such conditions.