     delay(500);
   }
   tray_state = TRAY_OPEN;
-  KCUP_LOADER, KCUP_EJECTOR, TRAY_PISTON
   return 0;
 }
 

  SUGAR = 0,
  MILK,
  HONEY,
}

char serial_buffer[BUFLEN] = {};
long serial_index = 0;

// Repeated calls will do nothing
// Never returns an error, ideally
int kcup_tray_close() {
  digitalWriteFast(PIN_TRAY_PISTON, TRAY_CLOSED);
  if (tray_state != TRAY_CLOSED) {
    delay(500);
  }
