Configuration.h on Marlin

 * :[-1, 0, 1, 2, 3, 4, 5, 6, 7]
 */
#define SERIAL_PORT -1

/**
 * Select a secondary serial port on the board to use for communication with the host.
 * :[-1, 0, 1, 2, 3, 4, 5, 6, 7]
 */
//#define SERIAL_PORT_2 -1

/**
 * This setting determines the communication speed of the printer.
 *
 * 250000 works in most cases, but you might try a lower speed if
 * you commonly experience drop-outs during host printing.
 * You may try up to 1000000 to speed up SD file transfer.
 *
 * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
 */
#define BAUDRATE 9600

// Enable the Bluetooth serial interface on AT90USB devices
//#define BLUETOOTH

// Choose the name from boards.h that matches your setup
#ifndef MOTHERBOARD
  #define MOTHERBOARD BOARD_RAMPS_14_SF
#endif