How to Use MKE-S02 LDR Light Sensor: Examples, Pinouts, and Specs

The MKE-S02 LDR Light Sensor is a photoresistor, also known as a light-dependent resistor (LDR), which is a passive electronic component whose resistance varies with the intensity of light it is exposed to. This characteristic makes it ideal for creating light-sensitive circuits, which can be used in a variety of applications such as automatic lighting control, alarm systems, and environmental light monitoring.

• Automatic night lights
• Security systems with light-based triggering
• Light intensity monitoring for agricultural applications
• Automatic street lighting
• Light-activated switches for consumer electronics

The MKE-S02 LDR Light Sensor has the following key technical specifications:

The MKE-S02 LDR Light Sensor is a two-terminal device:

1. Connecting the LDR: Connect one terminal of the LDR to a voltage source (Vcc) and the other terminal to an analog input pin of a microcontroller through a fixed resistor to form a voltage divider.
2. Choosing a Resistor: Select a fixed resistor value that is close to the resistance of the LDR at the light level you wish to detect.
3. Reading Values: Use the microcontroller's ADC (Analog-to-Digital Converter) to read the voltage across the fixed resistor, which varies with light intensity.

• Avoid exposing the LDR to extreme light intensities that could exceed its maximum voltage rating.
• Shield the sensor from artificial light sources when calibrating for natural light detection to prevent false readings.
• Use a capacitor in parallel with the LDR to smooth out rapid changes in light and to reduce noise in the ADC readings.

The following example demonstrates how to connect the MKE-S02 LDR Light Sensor to an Arduino UNO and read light levels.

Vcc (5V) --- LDR ---+--- Resistor (10kΩ) --- GND
                     |
                 Analog Pin A0

// Define the LDR pin
const int ldrPin = A0;

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

void loop() {
  // Read the value from the LDR
  int ldrValue = analogRead(ldrPin);
  
  // Convert the analog reading to a voltage
  float voltage = ldrValue * (5.0 / 1023.0);
  
  // Print out the value in the Serial Monitor
  Serial.print("LDR Value: ");
  Serial.print(ldrValue);
  Serial.print(" - Voltage: ");
  Serial.println(voltage);
  
  // Wait for a bit before reading again
  delay(500);
}

• Inconsistent Readings: Ensure that there are no loose connections and that the LDR is not exposed to intermittent light sources.
• No Change in Readings: Verify that the LDR is not damaged and that it is correctly connected in the voltage divider circuit.

• If readings are erratic, add a capacitor in parallel with the LDR to stabilize the readings.
• Ensure that the fixed resistor value is appropriate for the expected range of light levels.
• Calibrate your sensor by mapping the ADC readings to known light levels under controlled conditions.

Q: Can I use the MKE-S02 LDR Light Sensor with a 3.3V system?

A: Yes, the sensor can be used with a 3.3V system, but the voltage divider and ADC calculations will need to be adjusted accordingly.

Q: How do I calibrate the sensor for accurate light measurements?

A: Use a known light source and measure the resistance of the LDR under that condition. Then, compare the ADC readings to the expected values and adjust your code accordingly.

Q: What is the lifespan of the MKE-S02 LDR Light Sensor?

A: The lifespan can vary based on usage, but LDRs typically have a long operational life if used within their specified ratings. Avoid exposure to high-intensity light to prevent premature aging.