Update from F4 to F7 -> Performance Problems

mfrank9 · ‎2017-09-15

Posted on September 15, 2017 at 14:17

Hallo everybody,

i have a circuit board whitch is fitted with a STM32F429BIT.

The Software use STemWin and LWIP (without RTOS) and works good.

Now i has order the same circuit board with the pin compatible STM32F767BIT.

It is my first projekt with a F7.

Now i tested the LWIP with a terminal programm.

Then i tested STemWin. Also this worked perfectly.

But when I use both of them at the same time in the same code the LAN is very slow.

I have realised a tcp echo.

It sometimes takes up to 2 seconds until I get an answer.

I dont�t understand the Problem.

The AN4839 and AN4861 says that there is maybe a Problem with the DMA und the L1 Cache.

Maybe thats my problem. The solution is the use of the 'Managing memory protection unit (MPU)'.

I have init it as follows:

void MPU_Config(void)

{

MPU_Region_InitTypeDef MPU_InitStruct;

/* Disables the MPU */

HAL_MPU_Disable();

/**Initializes and configures the Region and the memory to be protected

*/

MPU_InitStruct.Enable = MPU_REGION_ENABLE;

MPU_InitStruct.Number = MPU_REGION_NUMBER0;

MPU_InitStruct.BaseAddress = 0xC0000000;

MPU_InitStruct.Size = MPU_REGION_SIZE_8MB;

MPU_InitStruct.SubRegionDisable = 0x0;

MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL1;

MPU_InitStruct.AccessPermission = MPU_REGION_FULL_ACCESS;

MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_ENABLE;

MPU_InitStruct.IsShareable = MPU_ACCESS_NOT_SHAREABLE;

MPU_InitStruct.IsCacheable = MPU_ACCESS_CACHEABLE;

MPU_InitStruct.IsBufferable = MPU_ACCESS_BUFFERABLE;

HAL_MPU_ConfigRegion(&MPU_InitStruct);

/**Initializes and configures the Region and the memory to be protected

*/

MPU_InitStruct.Enable = MPU_REGION_ENABLE;

MPU_InitStruct.Number = MPU_REGION_NUMBER1;

MPU_InitStruct.BaseAddress = 0xC0000000;

MPU_InitStruct.Size = MPU_REGION_SIZE_2MB;

MPU_InitStruct.SubRegionDisable = 0x0;

MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL1;

MPU_InitStruct.AccessPermission = MPU_REGION_FULL_ACCESS;

MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_DISABLE;

MPU_InitStruct.IsShareable = MPU_ACCESS_NOT_SHAREABLE;

MPU_InitStruct.IsCacheable = MPU_ACCESS_CACHEABLE;

MPU_InitStruct.IsBufferable = MPU_ACCESS_BUFFERABLE;

HAL_MPU_ConfigRegion(&MPU_InitStruct);

/**Initializes and configures the Region and the memory to be protected

*/

MPU_InitStruct.Enable = MPU_REGION_ENABLE;

MPU_InitStruct.Number = MPU_REGION_NUMBER2;

MPU_InitStruct.BaseAddress = 0x20020000;

MPU_InitStruct.Size = MPU_REGION_SIZE_512KB;

MPU_InitStruct.SubRegionDisable = 0x0;

MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL0;

MPU_InitStruct.AccessPermission = MPU_REGION_FULL_ACCESS;

MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_ENABLE;

MPU_InitStruct.IsShareable = MPU_ACCESS_SHAREABLE;

MPU_InitStruct.IsCacheable = MPU_ACCESS_CACHEABLE;

MPU_InitStruct.IsBufferable = MPU_ACCESS_NOT_BUFFERABLE;

HAL_MPU_ConfigRegion(&MPU_InitStruct);

/* Enables the MPU */

HAL_MPU_Enable(MPU_PRIVILEGED_DEFAULT);

}

I have testet following possibilities:

I&DCache | MPU | Resultat ------------------------------------------------------------------- | | Lan very slow. -------------------------------------------------------------------- x | | lan not available . | | LTDC has sometimes flickering. --------------------------------------------------------------------- x | x | lan slightly faster | | LTDC has sometimes flickering. --------------------------------------------------------------------- | x | lan slightly faster ---------------------------------------------------------------------

Is the configuration of the MPU ok or is something entirely different to my problem?

#cache #f7 #mpu

mfrank9 · ‎2017-09-17

Posted on September 18, 2017 at 07:36

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