 long time2 = 250;           // milliseconds of on-time
 
 //SD
-unsigned long previousMillis3 = 10000;        // will store last time LED was updated
+unsigned long previousMillis3 = 0;        // will store last time LED was updated
 long time3 = 500;           // milliseconds of on-time
+
+bool start = false;
 
 //MPU6050
 unsigned long previousMillis4 = 0;        // will store last time LED was updated


  readNMEA();

  if (currentMillis - previousMillis1 >= time1)
  {
    oled();
    previousMillis1 = currentMillis;  // Remember the time


  }

  if ((currentMillis - previousMillis3 >= time3) && (start == true) )
  {
    serial_data();
    previousMillis3 = currentMillis;  // Remember the time
