Label update doesn't work in V8.0.0

How-to
1

thanks to kindly comment, I success migration from v7.6.1 to v8.0.0.

now, I try to run lvgl sample app based on v8.0.0.

unfortunately, count_label isn’t updated and show as “Text”

it seems like “lv_label_set_text_fmt” didn’t work in while statement.

void main(void)
{
uint32_t count = 0U;
char count_str[11] = {0};
const struct device *display_dev;
lv_obj_t *hello_world_label;
lv_obj_t *count_label;

display_dev = device_get_binding(CONFIG_LVGL_DISPLAY_DEV_NAME);

if (display_dev == NULL) {
    LOG_ERR("device not found.  Aborting test.");
    return;
}

if (IS_ENABLED(CONFIG_LVGL_POINTER_KSCAN)) {
    lv_obj_t *hello_world_button;

    hello_world_button = lv_btn_create(lv_scr_act());
    lv_obj_align(hello_world_button, LV_ALIGN_CENTER, 0, 0);
    hello_world_label = lv_label_create(hello_world_button);
} else {
    hello_world_label = lv_label_create(lv_scr_act());
}

lv_label_set_text(hello_world_label, "Hello world!");
lv_obj_align(hello_world_label, LV_ALIGN_CENTER, 0, 0);

count_label = lv_label_create(lv_scr_act());
lv_obj_align(count_label, LV_ALIGN_BOTTOM_MID, 0, 0);

// lv_task_handler();
display_blanking_off(display_dev);

while (1) {
    lv_label_set_text_fmt(count_label, "%d", count);
    lv_task_handler();
    k_sleep(K_MSEC(1000));
    ++count;
}

}

2

after changing like below; count_label is updated now.

  •    while (1) {
         lv_label_set_text_fmt(count_label, "%d", count);
         lv_refr_now(NULL);           <<<<<<<<<<<<< add
          lv_task_handler();
          k_sleep(K_MSEC(1000));
          ++count;
  }

as far as I know, “lv_refr_now()” ans “lv_task_handler()” is quite similar. both thing are calling “_lv_disp_refr_timer” to call "flush_cb() " in lvgl v8.0.0.

what is difference between lv_refr_now() and lv_task_handler()?

Thanks

3

They are really the same.

It works for me in the simulator:

 lv_obj_t * label = lv_label_create(lv_scr_act());

  while (1) {
      lv_label_set_text_fmt(label, "%d", count);
      lv_task_handler();
      usleep(1000 * 1000);
      ++count;
  }

Please enble logging to see what happens.

Maybe there is a crash in an lv_task.

Have you changed your driver like this?

4

Hi kisvegabor

Thanks for your kindly comment.
when I checked in detail, as you comment, there is no problem in sample application.
the problem is lv_tick_get() doesn’t work caused by that I didn’t set system click(?) properly

more detail…

when I checked the difference the lv_refr_now() and lv_timer_create in v8.0.0. (cf. lv_task_create in v.7.6.1), there is a little bit difference regarding period.

lv_refr_now() is calling “_lv_disp_refr_timer()” immediately.
but, lv_timer_create() is calling “lv_timer_exec()” and there is some condition which checking the time_remaining in lv_timer_exec(). so if time remaining is 0, “_lv_disp_refr_timer()” is called.

as you know, when we call “lv_timer_create()”, we have to set the period (30 as default.
however, I didn’t set custom tick so lv_tick_get() always return 0.
so, this value never greater than default period(30) that’s why our display doesn’t update .

so I changed custom tick like below;

  • lv_conf.h
    #define LV_TICK_CUSTOM 1
    #if LV_TICK_CUSTOM
    #define LV_TICK_CUSTOM_INCLUDE “kernel.h”
    #define LV_TICK_CUSTOM_SYS_TIME_EXPR (k_uptime_get_32())
    #endif

that’s why this applpication is working well on your simulator.

Thanks
Best Regards

1 Like
5

A few weeks ago I added a feature to log a warning if LVGL’s tick is not incremented.
Have you seen that warning?

6

From your guide, I enable log. But lvgl log is not printed.
I think there is some problem in printing log.
So I can’t see that log.
Let me check log service firstly.
And could you let me know which log should be printed when lvgl thick isn’t working

Thanks
Best Regards

7

Thanks for your contributing!
My lv_timer doesn’t work for 2days, and I modify the LV_TICK_CUSTOM, it’s OK!!!