#include <Adafruit_NeoPixel.h>

#define LED_PIN 6

#define NUM_PIXELS 50

#define NUM_SENSORS 10

#define LEDS_PER_SENSOR (NUM_PIXELS / NUM_SENSORS)

#define BUTTON_PIN 13

Adafruit_NeoPixel strip(NUM_PIXELS, LED_PIN, NEO_GRB + NEO_KHZ800);

// Sensor pins

const int sensorPins[NUM_SENSORS] = {2, 3, 4, 5, 7, 8, 9, 10, 11, 12};

// LED color when ON

const uint8_t activeR = 255, activeG = 255, activeB = 255; // White

// State tracking

int lastState[NUM_SENSORS];

void setup() {

Serial.begin(9600);

strip.begin();

strip.show(); // Start with all off

// Setup sensor pins

for (int i = 0; i < NUM_SENSORS; i++) {

pinMode(sensorPins[i], INPUT_PULLUP);

lastState[i] = digitalRead(sensorPins[i]);

}

// Setup button pin

pinMode(BUTTON_PIN, INPUT_PULLUP);

Serial.println("IR sensors + button hold-to-turn-on ready!");

}

void loop() {

bool buttonPressed = (digitalRead(BUTTON_PIN) == LOW);

if (buttonPressed) {

// While the button is pressed, all LEDs on

setAll(activeR, activeG, activeB);

} else {

// Otherwise, LEDs respond to sensors

for (int i = 0; i < NUM_SENSORS; i++) {

int val = digitalRead(sensorPins[i]);

if (val != lastState[i]) {

int startLED = i * LEDS_PER_SENSOR;

int endLED = startLED + LEDS_PER_SENSOR;

if (val == LOW) {

// Beam broken → turn ON

setSection(startLED, endLED, activeR, activeG, activeB);

} else {

// Beam clear → turn OFF

setSection(startLED, endLED, 0, 0, 0);

}

lastState[i] = val;

}

}

}

}

// --- Turn all LEDs to one color ---

void setAll(uint8_t r, uint8_t g, uint8_t b) {

for (int j = 0; j < NUM_PIXELS; j++) {

strip.setPixelColor(j, strip.Color(r, g, b));

}

strip.show();

}

// --- Turn a section of LEDs to one color ---

void setSection(int startLED, int endLED, uint8_t r, uint8_t g, uint8_t b) {

for (int j = startLED; j < endLED; j++) {

strip.setPixelColor(j, strip.Color(r, g, b));

}

strip.show();

}