#include QMK_KEYBOARD_H enum custom_keycodes { KC_HELLO = SAFE_RANGE, }; const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = { LAYOUT_ortho_1x1(KC_HELLO) }; bool process_record_user(uint16_t keycode, keyrecord_t *record) { switch (keycode) { case KC_HELLO: if (record->event.pressed) { println("Hello world!"); } return false; } return true; } void keyboard_post_init_user(void) { // Customise these values to desired behaviour debug_enable=true; debug_matrix=true; //debug_keyboard=true; //debug_mouse=true; }