How to Use QTR 8A: Examples, Pinouts, and Specs

The QTR 8A, manufactured by ROBOLİG(KOKBORU) with part ID kokboru0042 Model, is an array of eight infrared emitter and detector pairs. This component is primarily used for line following and edge detection in robotics. It provides an analog voltage output corresponding to the reflectance of the surface, making it an essential component for autonomous robots and other applications requiring surface reflectance detection.

• Line Following Robots: The QTR 8A can be used to detect lines on the ground, allowing robots to follow a predefined path.
• Edge Detection: It can detect edges or boundaries, preventing robots from falling off surfaces.
• Surface Reflectance Measurement: The sensor array can measure the reflectance of different surfaces, useful in various industrial applications.

1. Power Supply: Connect the VCC pin to a 3.3V or 5V power supply and the GND pin to the ground.
2. Analog Outputs: Connect the OUT0 to OUT7 pins to the analog input pins of a microcontroller (e.g., Arduino UNO).
3. LED Control: Connect the LEDON pin to a digital output pin of the microcontroller to control the IR LEDs.

• Power Supply: Ensure that the power supply voltage is within the specified range (3.3V to 5V).
• Analog Readings: Use the analogRead() function on the Arduino to read the sensor values.
• LED Control: Use the digitalWrite() function to control the LEDON pin, turning the IR LEDs on or off as needed.
• Calibration: Calibrate the sensors for the specific surface and lighting conditions to improve accuracy.

// Sample code to read QTR 8A sensor values with Arduino UNO

// Define the analog input pins for the sensors
const int sensorPins[8] = {A0, A1, A2, A3, A4, A5, A6, A7};

// Define the digital output pin for controlling the IR LEDs
const int ledControlPin = 2;

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

  // Set the LED control pin as an output
  pinMode(ledControlPin, OUTPUT);

  // Turn on the IR LEDs
  digitalWrite(ledControlPin, HIGH);
}

void loop() {
  // Array to store sensor values
  int sensorValues[8];

  // Read the sensor values
  for (int i = 0; i < 8; i++) {
    sensorValues[i] = analogRead(sensorPins[i]);
  }

  // Print the sensor values to the serial monitor
  for (int i = 0; i < 8; i++) {
    Serial.print("Sensor ");
    Serial.print(i);
    Serial.print(": ");
    Serial.print(sensorValues[i]);
    Serial.print("\t");
  }
  Serial.println();

  // Add a small delay before the next reading
  delay(100);
}

1. No Output from Sensors:

   • Solution: Check the power supply connections and ensure the VCC and GND pins are properly connected.

2. Inconsistent Readings:

   • Solution: Calibrate the sensors for the specific surface and lighting conditions. Ensure the sensors are clean and free from dust.

3. IR LEDs Not Turning On:

   • Solution: Verify the connection to the LEDON pin and ensure it is set to HIGH using the digitalWrite() function.

• Check Connections: Ensure all connections are secure and correct.
• Power Supply: Verify that the power supply voltage is within the specified range.
• Sensor Calibration: Calibrate the sensors for the specific environment to improve accuracy.
• Serial Monitor: Use the Serial Monitor in the Arduino IDE to debug and monitor sensor values.

By following this documentation, users can effectively integrate the QTR 8A sensor array into their projects, ensuring accurate line following and edge detection capabilities.