Reflective Optical Sensor

// Pin number: change this to match your wiring
#define TRACKER_PIN 2  // Arduino digital pin connected to SIGNAL (e.g. D2)
#define LED_PIN 13     // LED pin (Arduino built-in LED on pin 13, or external LED)

void setup() {
  // Initialize pin modes
  pinMode(TRACKER_PIN, INPUT);  // Set line tracker pin as input (to read detection state)
  pinMode(LED_PIN, OUTPUT);     // Set LED pin as output (to control LED on/off)
  
  // Start serial for debugging (9600 baud)
  Serial.begin(9600);
  
  Serial.println("Line tracker program started");
  Serial.println("LED on when black line detected, LED off when white line detected");
}

void loop() {
  // Read line tracker state
  int trackerState = digitalRead(TRACKER_PIN);  // Read sensor pin level: HIGH(1)=black line detected, LOW(0)=white line detected
  
  // Control LED based on detection state
  if (trackerState == HIGH) {
    // Black line detected: LED on
    digitalWrite(LED_PIN, HIGH);
    Serial.println("Black line detected - LED on");
  } else {
    // White line detected: LED off
    digitalWrite(LED_PIN, LOW);
    Serial.println("White line detected - LED off");
  }
  
  delay(100);  // Brief delay to avoid reading too fast
}

# Import required modules
from machine import Pin  # GPIO control
import time              # For delay (time.sleep)

# Pin number: change these to match your wiring
TRACKER_PIN = 0    # GPIO connected to SIGNAL (e.g. GPIO 0)
LED_PIN = 1        # LED pin (GPIO 1, or external LED, Pico built-in LED is GPIO 25)

# Create pin objects
tracker = Pin(TRACKER_PIN, Pin.IN)  # Set line tracker pin as input (to read detection state)
led = Pin(LED_PIN, Pin.OUT)         # Set LED pin as output (to control LED on/off)

print("Line tracker program started")
print("LED on when black line detected, LED off when white line detected")

# Main loop: runs forever
while True:
    # Read line tracker state
    trackerState = tracker.value()   # Read sensor pin level: 1=black line detected (HIGH), 0=white line detected (LOW)
    
    # Control LED based on detection state
    if trackerState == 1:
        # Black line detected: turn LED on and print message
        led.on()                 # Output HIGH, LED on
        print("Black line detected - LED on")
    else:
        # White line detected: turn LED off
        led.off()                # Output LOW, LED off
        print("White line detected - LED off")
    
    # Delay 100 milliseconds to avoid reading too fast
    time.sleep_ms(100)