public static final char HEADER    = 'H';
public static final char A_TAG = 'M';
public static final char B_TAG = 'X';
public static final char C_TAG = 'U';
public static final char F_TAG = 'F';

void ephSerial() {
  
  for(int i = 0; i<colorsN; i++) {
    colorByteValues[i] = byte(colorValues[i]/(cellN/100));
    print(colorByteValues[i] + "\t");
  }
  println("");
  sendMessage(A_TAG, colorByteValues);
}


void sendMessage(char tag, byte[] cbv){
  // send the given index and value to the serial port
  port.write(HEADER);
  port.write(tag);
  
  for(int i=0; i<cbv.length; i++) {
    port.write(cbv[i]);
  }
  port.clear();
}


void serialEvent(Serial p) {
  // handle incoming serial data
  String inString = port.readStringUntil('\n');
  if(inString != null) {     
    print( inString );   // echo text string from Arduino
  }
}