FreeRtos and LVGL

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1

Hi everyone,
I want to integrate LVGL on an STM32 ARM MCU with FreeRtos.
I wanted to create a task that executes lv_task_handler () cyclically. All GUI updates will be in the same task where the lv_task_handler () function will be called.
The only “lv_…” functions outside this task are “lv_tick_inc()” which will be called in an interrupt routine and lv_flush_ready () which is called at the end of each SPI transfer (only when colors are sent).
Do I have to take precautions with any Mutexes or semaphores?

2

No, that sounds fine.

3

Hi I3uri1993,

When the hardware SPI is used to read the data, it is best to use the interrupt mutex semaphore protection.

4

Hi Lucifer,
I want to use SPI with DMA for better performance. A interrupt is triggered when DMA+SPI transfer is completed in background.
I can’t allow “lv_flush_ready” to be executed while I’m running “lv_task_handler”, is that correct?
I have to use interrupt semaphores for that?

5

With DMA the usual scenario is to call lv_flush_ready() from a “DMA ready” interrupt.
So you can simply call it.

6

In the documentation I read:
Try to avoid calling LittlevGL function from an interrupts (except lv_tick_inc() ). But if you really need to do this you have to disable the interrupt which uses LittlevGL functions while lv_task_handler is running. It’s a better approach to set a flag or other value and periodically check it in an lv_task .
Does It conflict with your answer?

7

It was really conflicting. I updated the documentation.

8

@l3uri1993 do you have achieved？ Can you give some suggestions? I will do it

9

Have you looked at this ?

I have since changed to the following, that way no mutex required,

static V RunEvery400Ms ( V )
{
	static UI ticksLastRun;
	UI ticksNow;

	UI msElapsed = Osa_msElapsedFrTicksMarked( ticksLastRun, &ticksNow );
	if( msElapsed >= 400 )
	{
		ticksLastRun = ticksNow;
		Screens_Every400ms();
	}
}

static V RunEvery1000Ms ( V )
{
	static UI ticksLastRun;
	UI ticksNow;

	UI msElapsed = Osa_msElapsedFrTicksMarked( ticksLastRun, &ticksNow );
	if( msElapsed >= 1000 )
	{
		ticksLastRun = ticksNow;
		Screens_Every1000ms();
	}
}

static V TaskLVGL ( PV p )
{
	for( ; ; )
	{
		vTaskDelay( pdMS_TO_TICKS(10) );
		
		RunEvery400Ms();
		RunEvery1000Ms();
		
		lv_task_handler();
	}
}