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Use state change detection and hysteresis for counting pulses in an analog signal.

const int lowerThreshold = 150;
const int upperThreshold = 200;

const uint8_t analogPin = A0;
const uint8_t ledPin = LED_BUILTIN;

void setup() {
  Serial.begin(115200);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  static bool state = LOW;
  static unsigned int counter = 0;

  int analogValue = analogRead(analogPin);
  if (state == HIGH) {
    if (analogValue < lowerThreshold) {
      state = LOW;
      counter++;
      Serial.println(counter);
      digitalWrite(ledPin, LOW);
    }
  } else { // state == LOW
    if (analogValue > upperThreshold) {
      state = HIGH;
      digitalWrite(ledPin, HIGH);
    }
  }
}

This sketch basically applies a software Schmitt trigger to the analog input signal, and increments the counter on each falling edge. (Rising edge of light intensity, because your LDR configuration inverts the signal.)

Use state change detection and hysteresis for counting pulses in an analog signal.

const int lowerThreshold = 150;
const int upperThreshold = 200;

const uint8_t analogPin = A0;
const uint8_t ledPin = LED_BUILTIN;

void setup() {
  Serial.begin(115200);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  static bool state = LOW;
  static unsigned int counter = 0;

  int analogValue = analogRead(analogPin);
  if (state == HIGH) {
    if (analogValue < lowerThreshold) {
      state = LOW;
      counter++;
      Serial.println(counter);
      digitalWrite(ledPin, LOW);
    }
  } else { // state == LOW
    if (analogValue > upperThreshold) {
      state = HIGH;
      digitalWrite(ledPin, HIGH);
    }
  }
}

This sketch basically applies a software Schmitt trigger to the analog input signal, and increments the counter on each falling edge. (Rising edge of light intensity, because your LDR configuration inverts the signal.)

The red waveform is the analog input from the LDR. The gray rectangular wave is the state (and the state of the LED). The counter is incremented at each black, vertical dashed line.

Use state change detection and hysteresis for counting pulses in an analog signal.

const int lowThreshold = 150;
const int highThreshold = 200;

const uint8_t analogPin = A0;
const uint8_t ledPin = LED_BUILTIN;

void setup() {
  Serial.begin(115200);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  static bool state = LOW;
  static unsigned int counter = 0;

  int analogValue = analogRead(analogPin);
  if (state == HIGH) {
    if (analogValue < lowThreshold) {
      state = LOW;
      digitalWrite(ledPin, LOW);
    }
  } else { // state == LOW
    if (analogValue > highThreshold) {
      state = HIGH;
      counter++;
      Serial.println(counter);
      digitalWrite(ledPin, HIGH);
    }
  }
}

Use state change detection and hysteresis for counting pulses in an analog signal.

const int lowerThreshold = 150;
const int upperThreshold = 200;

const uint8_t analogPin = A0;
const uint8_t ledPin = LED_BUILTIN;

void setup() {
  Serial.begin(115200);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  static bool state = LOW;
  static unsigned int counter = 0;

  int analogValue = analogRead(analogPin);
  if (state == HIGH) {
    if (analogValue < lowerThreshold) {
      state = LOW;
      counter++;
      Serial.println(counter);
      digitalWrite(ledPin, LOW);
    }
  } else { // state == LOW
    if (analogValue > upperThreshold) {
      state = HIGH;
      digitalWrite(ledPin, HIGH);
    }
  }
}

This sketch basically applies a software Schmitt trigger to the analog input signal, and increments the counter on each falling edge. (Rising edge of light intensity, because your LDR configuration inverts the signal.)

Use state change detection and hysteresis for counting pulses in an analog signal.

const int lowThreshold = 150;
const int highThreshold = 200;

const uint8_t analogPin = A0;
const uint8_t ledPin = LED_BUILTIN;

void setup() {
  Serial.begin(115200);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  static bool state = LOW;
  static unsigned int counter = 0;

  int analogValue = analogRead(analogPin);
  if (state == HIGH ) {
    if (analogValue < lowThreshold) {
      state = LOW;
      digitalWrite(ledPin, LOW);
    }
  } else {
    if (analogValue > highThreshold) {
      state = HIGH;
      counter++;
      Serial.println(counter);
      digitalWrite(ledPin, HIGH);
    }
  }
}

Use state change detection and hysteresis for counting pulses in an analog signal.

const int lowThreshold = 150;
const int highThreshold = 200;

const uint8_t analogPin = A0;
const uint8_t ledPin = LED_BUILTIN;

void setup() {
  Serial.begin(115200);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  static bool state = LOW;
  static unsigned int counter = 0;

  int analogValue = analogRead(analogPin);
  if (state == HIGH) {
    if (analogValue < lowThreshold) {
      state = LOW;
      digitalWrite(ledPin, LOW);
    }
  } else { // state == LOW
    if (analogValue > highThreshold) {
      state = HIGH;
      counter++;
      Serial.println(counter);
      digitalWrite(ledPin, HIGH);
    }
  }
}