const int ledPin = 13; 
const int unitTime = 200; 

unsigned long previousMillis = 0;
int dotDuration = unitTime; // Duration of a dot

void setup() {
  pinMode(ledPin, OUTPUT); // Initialize the LED pin as an output
  digitalWrite(ledPin, HIGH); // Ensure LED is initially off
  Serial.begin(9600); 
  Serial.println("ENTER HERE:");
}

// Morse code representation for A-Z and 0-9
const char* morseCode[] = {
  ".-", "-...", "-.-.", "-..", ".", "..-.", "--.", "....", "..", ".---",
  "-.-", ".-..", "--", "-.", "---", ".--.", "--.-", ".-.", "...", "-",
  "..-", "...-", ".--", "-..-", "-.--", "--..",
  "-----", ".----", "..---", "...--", "....-", ".....", "-....", "--...", "---..", "----."
};

// Function to blink a dot
void dot() {
  digitalWrite(ledPin, LOW); // Turn the LED on
  delay(dotDuration); // Wait for dot duration
  digitalWrite(ledPin, HIGH); // Turn the LED off
}

// Function to blink a dash
void dash() {
  digitalWrite(ledPin, LOW); // Turn the LED on
  delay(dotDuration * 3); // Wait for dash duration
  digitalWrite(ledPin, HIGH); // Turn the LED off
}

// Function to pause between Morse code characters
void morsePause() {
  digitalWrite(ledPin, HIGH); // Ensure LED is off during the pause
  delay(1000); // Pause for 1000 milliseconds
}

// Function to convert a character to Morse code and blink it
void morseCharacter(char ch) {
  if (ch == ' ') {
    delay(unitTime * 3); // Wait for 3 unit times for space between words
    return;
  }

  if (ch >= 'A' && ch <= 'Z') {
    const char* code = morseCode[ch - 'A'];
    while (*code) {
      if (*code == '.') {
        dot();
        delay(unitTime); // Wait for space between dot and dash
      }
      else if (*code == '-') {
        dash();
        delay(unitTime); // Wait for space between dot and dash
      }
      code++;
    }
  }
  else if (ch >= '0' && ch <= '9') {
    const char* code = morseCode[ch - '0' + 26];
    while (*code) {
      if (*code == '.') {
        dot();
        delay(unitTime); // Wait for space between dot and dash
      }
      else if (*code == '-') {
        dash();
        delay(unitTime); // Wait for space between dot and dash
      }
      code++;
    }
  }
  morsePause(); // Pause after each Morse code character
}

void loop() {
  if (Serial.available() > 0) {
    String inputString = Serial.readStringUntil('\n'); // Read the input string until newline character
    inputString.toUpperCase(); // Convert the input string to uppercase

    // Convert and blink each character of the input string in Morse code
    for (int i = 0; i < inputString.length(); i++) {
      char ch = inputString.charAt(i);
      morseCharacter(ch);
    }
  }
}