Transmit data using laser module problem

Projects Programming
1

I have project for the university and I want to transmit data between tow around and , when I set the code I marge it to be transmit and receive, for the first time it work but when I turn off everything and try to do it again never work can any one help me please.
The code:

#define SOLARPIN A0
#define THRESHOLD 210

int ambientReading = 0;

void setup() {
  pinMode (LASERPIN, OUTPUT);
  Serial.begin(9600);
  pinMode(SOLARPIN, INPUT);
  Serial.begin(4800);
}

void loop() {
  if (Serial.available() > 0) {
    String myText = Serial.readStringUntil('\n'); // read the incoming string until newline character is detected
    int length = myText.length();
    int ar[length];
    int m;
    int bits[8];
    
    for (int i = 0; i < length; i++) {
      ar[i] = int(myText.charAt(i)); // convert each character to its ASCII value and store it in an array
    }
    
    for (int n = 0; n < length; n++) {
      m = ar[n];
      int z;
      int bin[7];
      int newbin[7];
      
      // convert decimal value to binary
      for (z = 0; z < 8; z++) {
        bin[z] = m % 2;
        m = m / 2;
      }
      
      // reverse the order of binary digits
      for (int j = 7; j >= 0; j--) {
        newbin[7-j] = bin[j];
      }
      
      // set the first bit to HIGH to indicate the start of a new character
      newbin[0] = HIGH;
      
      // transmit each bit of the binary value using the laser
      for (int i = 0; i < 8; i++) {
        digitalWrite(LASERPIN, newbin[i]);
        delay(10);
      }
      
      // turn off the laser after transmitting all bits of the character
      digitalWrite(LASERPIN, LOW);
      
      // add a delay between characters
      delay(100);
    }
  }
  

  int reading = analogRead(SOLARPIN);

  int bits[8];

  //Listening for the start bit
  if (reading > THRESHOLD) {
    for (int i =0; i<8 ; i++) {
      if (analogRead(SOLARPIN) > THRESHOLD) {
        bits[i] = 1 ;
      }
      else {
        bits[i] = 0;
      }
      delay(10);
    }

    int m = 0;
    for (int j =1; j <8; j++) {
    if (bits[j] ==1) {
      m = m + (1<<(7-j));
    }
    }
  
    char n=m;
    Serial.print(n);
  
  }
}
2

If your arduino has a reset button, does pressing that make your project work or not work?

3

You have to enter a new line for each run.