STM32H7 and FreeRTOS with MPU

Kernel
1

jffglima wrote on Monday, November 26, 2018:

Hello everyone,

For my current project I need the FreeRTOS+MPU to work on H7. I got it somehow to work when I use DTCMs. However, when I try to move the complete memory allocation to the AXI SRAMs the FreeRTOS is hanging in the systick handler (there is a for(;:wink: there and goes out with break instructions).

After some experiments it was found that the system works if I do the following:
ā€¢Disable the DCACHE completly or
ā€¢Set an MPU region for the freeRTOS heap memory as non-cacheable (TEX = 001b, c = 0b, b = 0b)

I dont understand how I can have a cache coehrency problem since I dont have any DMAs or other processes writing into the AXI ram. The project is very very simple. It is just one thread and in the run function I have a counter incrementing.

To map the FreeRTOS to H7 I follow the steps on the following thread:

https://freertos.org/FreeRTOS_Support_Forum_Archive/May_2018/freertos_Cortex-M7_MPU_a9b4e3d5j.html

I attach the Attolic project here. in the main.h there are two compile switches. The system works if the ENABLE_DCACHE is commented or both ENABLE_DCACHE and ENABLE_NON_CACHEABLE_FREERTOS_HEAP are enabled.

I am running out of ideas what to try. Any help would be great.

Thanks a lot,
Best regards,
Joao

2

jffglima wrote on Thursday, December 06, 2018:

If I use the exactly same code but use a F7 instead, then I dont see the problem. Is there any difference in terms of cache configuration that we would need to do to the H7?

Any Ideas would be very welcome

Thanks
Joao

3

rtel wrote on Thursday, December 06, 2018:

Do the two boards have the same core revision number? If the hardware
has an r0p1 revision of the Cortex-M core then you need to use the
special FreeRTOS version that accounts for the silicon errata.

4

jffglima wrote on Friday, December 07, 2018:

Hello Richard,

Thanks for the reply. My H7 board has the r1p1 and F7 the r1p0, so I guess the H7 is even newer. But in any case I have taken the MPU M4 port version and merged the errata related changes. I have them in the xPortPendSVHandler. I also tried to place ā€œdsbā€ and ā€œisbā€ instruction every time a set of MPU registers are set but did not help. The code gets stuck in the function xTaskIncrementTick, within the for(;:wink: loop. Can that give any hint? My only thread is just counting variables up and then I call the vTaskDelay.

The problems seems to be related with tasks sleeping and waking them up. If I just exchange the vTaskDelay by a portYIELD, then the system does not stuck, but I need the vTaskDelay in my application :slight_smile:

below is my only task code.

Thanks a lot!
Br,
Joao

void TC_Run( void *pvParameters)
{

while(1)
{
	tTcPrivate1.receive_counter++;
	tTcPrivate2.receive_counter++;
	tTcPrivate3.receive_counter++;
	tTcPrivate4.receive_counter++;
	tTcPrivate5.receive_counter++;
	tTcPrivate6.receive_counter++;
	tTcPrivate7.receive_counter++;
	tTcPrivate8.receive_counter++;
	tTcPrivate9.receive_counter++;
	tTcPrivate10.receive_counter++;
	tTcPrivate11.receive_counter++;
	tTcPrivate12.receive_counter++;
	portYIELD();
	//osDelay(1);

}

}

5

daimonion1980 wrote on Thursday, February 21, 2019:

Hey joao
Could you solve your problem?
Iā€™m actually trying to get freertos10 to work on stm32H7 but still didnā€™t found an r1p1 port.

6

rtel wrote on Thursday, February 21, 2019:

If you donā€™t have an r0p1 core then you can just use the Cortex-M4F port

  • are you facing any other issue?
7

daimonion1980 wrote on Thursday, February 21, 2019:

Actually iā€™m trying to understand the whole cubeMX HAL/CMSIS FreeRTOS Stuff and try to separate the freeRTOS Stuff from cubeMX to use freertos 10 instead of 9. And this is the only thread where there is a working project with freertos10 on stm32h7. :wink:

8

rtel wrote on Thursday, February 21, 2019:

Updating from V9.x to V10.x should be straight forward:
https://www.freertos.org/FreeRTOS-V10.html

9

And what if we do have a r0p1 core?

10

Here is the answer - FreeRTOS-Kernel/ReadMe.txt at main Ā· FreeRTOS/FreeRTOS-Kernel Ā· GitHub