int DP_LED = 16;
int command;

// the setup function runs once when you press reset or power the board
void setup() {
  pinMode(16, OUTPUT);

  Serial1.begin(115200);
  delay(100);

  Serial1.println("Type s to start!\n");

  while(!Serial1.available() > 0);
  command = Serial1.read();
  
  if(command == 's'){
    Serial1.println("Blinking DP LED every 500ms!");
  }
  else {
    Serial1.println("Command is wrong!");
    exit(1);
  } 
}
// the loop function runs over and over again forever
void loop() {

  digitalWrite(DP_LED, HIGH);  // turn the LED off (HIGH is the voltage level)
  Serial1.print("DP LED is OFF!\n");
  delay(500);                      

  digitalWrite(DP_LED, LOW);  // turn the LED on 
  Serial1.print("DP LED is ON!\n");
  delay(500);                
}