How to Use KY-028: Examples, Pinouts, and Specs

The KY-028 is a temperature sensor module designed for temperature monitoring applications. It features the LM35 temperature sensor, which provides an analog output directly proportional to the ambient temperature. The module also includes a digital output that can be triggered when the temperature exceeds a user-defined threshold, making it versatile for various projects.

• Environmental temperature monitoring
• Home automation systems
• Industrial temperature control
• Educational projects and prototyping
• Arduino-based temperature sensing projects

The KY-028 module is built for simplicity and ease of use. Below are its key technical details:

The KY-028 module has four pins, as described in the table below:

The KY-028 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 a 3.3V or 5V power source and the GND pin to the ground.
2. Read Analog Temperature Data: Connect the AO pin to an analog input pin on your microcontroller (e.g., Arduino) to read the temperature as a voltage.
3. Set the Digital Threshold:
   • Use the onboard potentiometer to adjust the temperature threshold.
   • When the temperature exceeds this threshold, the DO pin will output HIGH (5V).
4. Monitor Digital Output: Connect the DO pin to a digital input pin on your microcontroller to detect when the threshold is crossed.

• Power Supply: Ensure the module is powered within its operating voltage range (3.3V - 5V).
• Calibration: For accurate temperature readings, calibrate the sensor in a controlled environment.
• Potentiometer Adjustment: Turn the potentiometer clockwise to increase the threshold and counterclockwise to decrease it.
• Avoid Overheating: Do not expose the module to temperatures beyond its specified range (-55°C to +150°C).

Below is an example code snippet to read both analog and digital outputs from the KY-028 module using an Arduino UNO:

// KY-028 Temperature Sensor Example with Arduino UNO

// Define pin connections
const int analogPin = A0;  // AO pin connected to analog pin A0
const int digitalPin = 2;  // DO pin connected to digital pin 2

void setup() {
  Serial.begin(9600);       // Initialize serial communication
  pinMode(digitalPin, INPUT); // Set digital pin as input
}

void loop() {
  // Read analog temperature value
  int analogValue = analogRead(analogPin);
  float voltage = analogValue * (5.0 / 1023.0); // Convert to voltage
  float temperature = voltage * 100.0;         // Convert voltage to temperature (°C)

  // Read digital output
  int digitalValue = digitalRead(digitalPin);

  // Print results to Serial Monitor
  Serial.print("Temperature (°C): ");
  Serial.print(temperature);
  Serial.print(" | Digital Output: ");
  Serial.println(digitalValue);

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

1. No Output from AO Pin:

   • Cause: Incorrect wiring or insufficient power supply.
   • Solution: Double-check the connections and ensure the module is powered with 3.3V or 5V.

2. DO Pin Always HIGH or LOW:

   • Cause: Threshold not set correctly.
   • Solution: Adjust the potentiometer to set the desired temperature threshold.

3. Inaccurate Temperature Readings:

   • Cause: Lack of calibration or external interference.
   • Solution: Calibrate the sensor in a controlled environment and avoid placing it near heat sources or fans.

4. Module Overheating:

   • Cause: Exposure to temperatures beyond the specified range.
   • Solution: Ensure the module operates within the -55°C to +150°C range.

Q1: Can the KY-028 module measure negative temperatures?
Yes, the LM35 sensor on the KY-028 module can measure temperatures as low as -55°C. However, ensure your microcontroller can interpret the corresponding analog voltage.

Q2: How do I reset the temperature threshold?
You can reset the threshold by turning the onboard potentiometer. Use a small screwdriver to adjust it clockwise or counterclockwise.

Q3: Can I use the KY-028 with a 3.3V microcontroller?
Yes, the KY-028 is compatible with 3.3V systems. Ensure the VCC pin is connected to a 3.3V power source.

Q4: What is the resolution of the analog output?
The resolution depends on the ADC (Analog-to-Digital Converter) of your microcontroller. For example, the Arduino UNO has a 10-bit ADC, providing a resolution of 0.00488V per step.

By following this documentation, you can effectively integrate the KY-028 module into your projects for reliable temperature monitoring.