Começando

void my_flush_cb(lv_disp_drv_t * disp_drv, const lv_area_t * area, lv_color_t * color_p) {
    ili9341_set_top_left_limit(area->x1, area->y1);   ili9341_set_bottom_right_limit(area->x2, area->y2);
    ili9341_copy_pixels_to_screen(color_p,  (area->x2 - area->x1) * (area->y2 - area->y1));

    /* IMPORTANT!!!
    * Inform the graphics library that you are ready with the flushing*/
    lv_disp_flush_ready(disp_drv);
}

/* board and sys init */
board_init();
sysclk_init();
configure_console();

/* LCd int */
configure_lcd();
ili9341_init();
configure_touch();
ili9341_backlight_on();

/*LittlevGL init*/
lv_init();
lv_disp_drv_t disp_drv;                 /*A variable to hold the drivers. Can be local variable*/
lv_disp_drv_init(&disp_drv);            /*Basic initialization*/
lv_disp_buf_init(&disp_buf, buf_1, NULL, LV_HOR_RES_MAX * LV_VER_RES_MAX);  /*Initialize `disp_buf` with the buffer(s) */
disp_drv.buffer = &disp_buf;            /*Set an initialized buffer*/
disp_drv.flush_cb = my_flush_cb;        /*Set a flush callback to draw to the display*/
lv_disp_t * disp;
disp = lv_disp_drv_register(&disp_drv); /*Register the driver and save the created display objects*/

/* Init input on LVGL */
lv_indev_drv_t indev_drv;
lv_indev_drv_init(&indev_drv);      /*Basic initialization*/
indev_drv.type = LV_INDEV_TYPE_POINTER;
indev_drv.read_cb = my_input_read;
/*Register the driver in LVGL and save the created input device object*/
lv_indev_t * my_indev = lv_indev_drv_register(&indev_drv);

void lv_ex_btn_1(void) {
    lv_obj_t * label;

    lv_obj_t * btn1 = lv_btn_create(lv_scr_act(), NULL);
    lv_obj_set_event_cb(btn1, event_handler);
    lv_obj_align(btn1, NULL, LV_ALIGN_CENTER, 0, -40);

    label = lv_label_create(btn1, NULL);
    lv_label_set_text(label, "Button");

    lv_obj_t * btn2 = lv_btn_create(lv_scr_act(), NULL);
    lv_obj_set_event_cb(btn2, event_handler);
    lv_obj_align(btn2, NULL, LV_ALIGN_CENTER, 0, 40);
    lv_btn_set_checkable(btn2, true);
    lv_btn_toggle(btn2);
    lv_btn_set_fit2(btn2, LV_FIT_NONE, LV_FIT_TIGHT);

    label = lv_label_create(btn2, NULL);
    lv_label_set_text(label, "Toggled");
}

static void event_handler(lv_obj_t * obj, lv_event_t event) {
    if(event == LV_EVENT_CLICKED) {
        printf("Clicked\n");
    }
    else if(event == LV_EVENT_VALUE_CHANGED) {
        printf("Toggled\n");
    }
}