tmk_keyboard/keyboard/ergodox/keymap_cub.h

static const uint8_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
    /* Keymap 0: Default Layer
     *
     * ,--------------------------------------------------.           ,--------------------------------------------------.
     * |   ~    |   1  |   2  |   3  |   4  |   5  |   \  |           |   '  |   6  |   7  |   8  |   9  |   0  |   =    |
     * |--------+------+------+------+------+-------------|           |------+------+------+------+------+------+--------|
     * | Tab    |   Q  |   W  |   E  |   R  |   T  | ~Fn1 |           | ~Fn3 |   Y  |   U  |   I  |   O  |   P  |   [    |
     * |--------+------+------+------+------+------|      |           |      |------+------+------+------+------+--------|
     * | LShift |   A  |   S  |   D  |   F  |   G  |------|           |------|   H  |   J  |   K  |   L  |   ;  | RShift |
     * |--------+------+------+------+------+------|  Fn0 |           | ~Fn4 |------+------+------+------+------+--------|
     * | LCtrl  |   Z  |   X  |   C  |   V  |   B  |      |           |      |   N  |   M  |   ,  |   .  |   /  | RCtrl  |
     * `--------+------+------+------+------+-------------'           `-------------+------+------+------+------+--------'
     *   | ~Fn1 | ~Fn2 | Caps | LAlt | LGui |                                       |  Lft |  Up  |  Dn  | Rght | ~Fn4 |
     *   `----------------------------------'                                       `----------------------------------'
     *                                        ,-------------.       ,-------------.
     *                                        | +Fn2 | Home |       | PgUp | Del  |
     *                                 ,------|------|------|       |------+------+------.
     *                                 |      |      |  End |       | PgDn |      |      |
     *                                 | BkSp |  ESC |------|       |------| Enter| Space|
     *                                 |      |      |  Spc |       | Ins  |      |      |
     *                                 `--------------------'       `--------------------'
     */

    KEYMAP(  // layout: layer 0: default
        // left hand
        GRV, 1,   2,   3,   4,   5,   BSLS,
        TAB, Q,   W,   E,   R,   T,   FN1,
        LSFT,A,   S,   D,   F,   G,
        LCTL,Z,   X,   C,   V,   B,   FN0,
        FN1, FN6, CAPS,LALT,LGUI,
                                      FN2, HOME,
                                           END,
                                 FN8, FN9, FN10,
        // right hand
             QUOT,6,   7,   8,   9,   0,   EQL,
             FN3, Y,   U,   I,   O,   P,   LBRC,
                  FN16,J,   K,   L,   SCLN,FN14,
             FN4, N,   M,   COMM,DOT, SLSH,FN15,
                       LEFT,UP,  DOWN,RGHT,FN4,
        PGUP,DEL,
        PGDN,
        FN11,FN12,FN13
    ),

    KEYMAP(  // layout: layer 1: F-keys instead of numbers
        // left hand
        TRNS,F1,  F2,  F3,  F4,  F5,  F6,
        TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,
        TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,
        TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,
        TRNS,TRNS,TRNS,TRNS,TRNS,
                                      TRNS,TRNS,
                                           TRNS,
                                 TRNS,TRNS,TRNS,
        // right hand
             F7,  F8,  F9,  F10, F11, F12, TRNS,
             TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,
                  TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,
             TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,
                       TRNS,TRNS,TRNS,TRNS,TRNS,
        TRNS,TRNS,
        TRNS,
        TRNS,TRNS,TRNS
    ),

    KEYMAP(  // layout: layer 2: mouse + numpad
        // left hand
        TRNS,NO,  NO,  NO,  NO,  PAUS,PSCR,
        TRNS,WH_L,WH_U,WH_D,WH_R,BTN2,TRNS,
        TRNS,MS_L,MS_U,MS_D,MS_R,BTN1,
        TRNS,NO,  NO,  NO,  NO,  BTN3,TRNS,
        TRNS,TRNS,TRNS,TRNS,TRNS,
                                      TRNS,TRNS,
                                           TRNS,
                                 TRNS,TRNS,TRNS,
        // right hand
             SLCK,NLCK,PSLS,PAST,PAST,PMNS,BSPC,
             TRNS,NO,  P7,  P8,  P9,  PMNS,BSPC,
                  TRNS,P4,  P5,  P6,  PPLS,PENT,
             TRNS,NO,  P1,  P2,  P3,  PPLS,PENT,
                       P0,  PDOT,SLSH,PENT,PENT,
        TRNS,TRNS,
        TRNS,
        TRNS,TRNS,TRNS
    ),

    KEYMAP(  // layout: layer 3: F-keys only
        // left hand
        TRNS,NO,  NO,  NO,  NO,  NO,  NO,  
        TRNS,F13, F14, F15, F16, NO,  TRNS,
        TRNS,F17, F18, F19, F20, NO,  
        TRNS,F21, F22, F23, F24, NO,  TRNS,
        TRNS,TRNS,TRNS,TRNS,TRNS,
                                      TRNS,TRNS,
                                           TRNS,
                                 TRNS,TRNS,TRNS,
        // right hand
             NO,  NO,  NO,  NO,  NO,  NO,  TRNS,
             TRNS,NO,  F1,  F2,  F3,  F4,  TRNS,
                  NO,  F5,  F6,  F7,  F8,  TRNS,
             TRNS,NO,  F9,  F10, F11, F12, TRNS,
                       TRNS,TRNS,TRNS,TRNS,TRNS,
        TRNS,TRNS,
        TRNS,
        TRNS,TRNS,TRNS
    ),

    KEYMAP(  // layout: layer 4: F-keys + cursor
        // left hand
        TRNS,F1,  F2,  F3,  F4,  F5,  F6,
        FN7, NO,  PGUP,UP,  PGDN,PGUP,TRNS,
        TRNS,NO,  LEFT,DOWN,RGHT,PGDN,
        TRNS,NO,  NO,  END, HOME,NO,  TRNS,
        FN5, TRNS,TRNS,TRNS,TRNS,
                                      TRNS,TRNS,
                                           TRNS,
                                 TRNS,TRNS,TRNS,
        // right hand
             F7,  F8,  F9,  F10, F11, F12, MINS,
             TRNS,PGUP,PGUP,UP,  PGDN,NO,  FN7,
                  PGDN,LEFT,DOWN,RGHT,NO,  TRNS,
             TRNS,NO,  HOME,END, NO,  NO,  TRNS,
                       TRNS,TRNS,TRNS,TRNS,TRNS,
        TRNS,TRNS,
        TRNS,
        TRNS,TRNS,TRNS
    ),

    KEYMAP(  // layout: layer 5: Workman layout
        // left hand
        TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,
        TRNS,Q,   D,   R,   W,   B,   TRNS,
        TRNS,A,   S,   H,   T,   G,
        TRNS,Z,   X,   M,   C,   V,   TRNS,
        TRNS,TRNS,TRNS,TRNS,TRNS,
                                      TRNS,TRNS,
                                           TRNS,
                                 TRNS,TRNS,TRNS,
        // right hand
             TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,
             TRNS,J,   F,   U,   P,   4,   TRNS,
                  Y,   N,   E,   O,   I,   TRNS,
             TRNS,K,   L,   TRNS,TRNS,TRNS,TRNS,
                       TRNS,TRNS,TRNS,TRNS,TRNS,
        TRNS,TRNS,
        TRNS,
        TRNS,TRNS,TRNS
    ),

/*
    // templates to copy from

    KEYMAP(  // layout: layer N: transparent on edges, all others are empty
        // left hand
        TRNS,NO,  NO,  NO,  NO,  NO,  NO,  
        TRNS,NO,  NO,  NO,  NO,  NO,  TRNS,
        TRNS,NO,  NO,  NO,  NO,  NO,  
        TRNS,NO,  NO,  NO,  NO,  NO,  TRNS,
        TRNS,TRNS,TRNS,LALT,LGUI,
                                      TRNS,TRNS,
                                           TRNS,
                                 LCTL,LSFT,TRNS,
        // right hand
             NO,  NO,  NO,  NO,  NO,  NO,  TRNS,
             TRNS,NO,  NO,  NO,  NO,  NO,  TRNS,
                  NO,  NO,  NO,  NO,  NO,  TRNS,
             TRNS,NO,  NO,  NO,  NO,  NO,  TRNS,
                       RGUI,RALT,TRNS,TRNS,TRNS,
        TRNS,TRNS,
        TRNS,
        TRNS,RSFT,RCTL
    ),
    KEYMAP(  // layout: layer N: fully transparent
        // left hand
        TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,
        TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,
        TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,
        TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,
        TRNS,TRNS,TRNS,TRNS,TRNS,
                                      TRNS,TRNS,
                                           TRNS,
                                 TRNS,TRNS,TRNS,
        // right hand
             TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,
             TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,
                  TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,
             TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,TRNS,
                       TRNS,TRNS,TRNS,TRNS,TRNS,
        TRNS,TRNS,
        TRNS,
        TRNS,TRNS,TRNS
    ),
*/

};

/* id for user defined functions */
enum function_id {
    TEENSY_KEY,
};

/*
 * Fn action definition
 */
static const uint16_t PROGMEM fn_actions[] = {
    ACTION_LAYER_SET(0, ON_BOTH),                   // FN0 - switch to Layer0
    ACTION_LAYER_MOMENTARY(1),                      // FN1 - push Layer1
    ACTION_LAYER_SET(2, ON_BOTH),                   // FN2 - switch to Layer2
    ACTION_LAYER_MOMENTARY(3),                      // FN3 - push Layer3
    ACTION_LAYER_MOMENTARY(4),                      // FN4 - push Layer4
    ACTION_LAYER_SET(5, ON_BOTH),                   // FN5 - switch to Layer5
    ACTION_LAYER_MOMENTARY(2),                      // FN6 - push Layer2
    ACTION_FUNCTION(TEENSY_KEY),                    // FN7 - Teensy key

    ACTION_MODS_TAP_KEY(MOD_LCTL, KC_BSPC),         // FN8  = LShift with tap BackSpace
    ACTION_MODS_TAP_KEY(MOD_LSFT, KC_ESC),          // FN9  = LCtrl with tap Escape
    ACTION_MODS_TAP_KEY(MOD_LALT, KC_SPC),          // FN10 = LAlt with tap Space
    ACTION_MODS_TAP_KEY(MOD_RALT, KC_INS),          // FN11 = RAlt with tap Ins
    ACTION_MODS_TAP_KEY(MOD_RSFT, KC_ENT),          // FN12 = RShift with tap Enter
    ACTION_MODS_TAP_KEY(MOD_RCTL, KC_SPC),          // FN13 = RCtrl with tap Space
    ACTION_MODS_TAP_KEY(MOD_RSFT, KC_MINS),         // FN14 = RShift with tap Enter
    ACTION_MODS_TAP_KEY(MOD_RCTL, KC_RBRC),         // FN15 = RCtrl with tap Space

    ACTION_LAYER_TAP_KEY(2, KC_H),                  // FN16 = L2 symbols on J key, to use with Mouse keys
};

void action_function(keyrecord_t *event, uint8_t id, uint8_t opt)
{
    print("action_function called\n");
    print("id  = "); phex(id); print("\n");
    print("opt = "); phex(opt); print("\n");
    if (id == TEENSY_KEY) {
        clear_keyboard();
        print("\n\nJump to bootloader... ");
        _delay_ms(250);
        bootloader_jump(); // should not return
        print("not supported.\n");
    }
}