Tick interface¶
LVGL needs a system tick to know elapsed time for animations and other tasks.
You need to call the lv_tick_inc(tick_period)
function periodically and provide the call period in milliseconds. For example, lv_tick_inc(1)
when calling every millisecond.
lv_tick_inc
should be called in a higher priority routine than lv_task_handler()
(e.g. in an interrupt) to precisely know the elapsed milliseconds even if the execution of lv_task_handler
takes more time.
With FreeRTOS lv_tick_inc
can be called in vApplicationTickHook
.
On Linux based operating systems (e.g. on Raspberry Pi) lv_tick_inc
can be called in a thread like below:
void * tick_thread (void *args)
{
while(1) {
usleep(5*1000); /*Sleep for 5 millisecond*/
lv_tick_inc(5); /*Tell LVGL that 5 milliseconds were elapsed*/
}
}
API¶
Provide access to the system tick with 1 millisecond resolution
Functions
-
uint32_t lv_tick_get(void)¶
Get the elapsed milliseconds since start up
- Returns
the elapsed milliseconds
-
uint32_t lv_tick_elaps(uint32_t prev_tick)¶
Get the elapsed milliseconds since a previous time stamp
- Parameters
prev_tick -- a previous time stamp (return value of lv_tick_get() )
- Returns
the elapsed milliseconds since 'prev_tick'