qmk_firmware/keyboards/planck/keymaps/thermal_printer/config.h

#ifndef CONFIG_USER_H
#define CONFIG_USER_H

#include "../../config.h"

#define SERIAL_UART_BAUD 19200

/*
 * MIDI options
 */

/* enable basic MIDI features:
   - MIDI notes can be sent when in Music mode is on
*/
#define MIDI_BASIC

/* enable advanced MIDI features:
   - MIDI notes can be added to the keymap
   - Octave shift and transpose
   - Virtual sustain, portamento, and modulation wheel
   - etc.
*/
//#define MIDI_ADVANCED

/* override number of MIDI tone keycodes (each octave adds 12 keycodes and allocates 12 bytes) */
//#define MIDI_TONE_KEYCODE_OCTAVES 2

 #endif