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stm32f7xxx memory card - TCM.

AVI-crak
Senior
Posted on May 14, 2017 at 01:12

The description of the stm32f746bg series has lines:

and L1-cache: 4KB data cache and 4KB instruction cache

SRAM: 320KB (including 64KB of data TCM RAM for critical real-time data) + 16KB of instruction TCM RAM (for critical real-time routines) + 4KB of backup SRAM (available in the lowest power modes).

But there is no exact determination about possible overlapping of addresses.

The first question - L1-cache is a part of a kernel? It isn't a part available memories? I want to use 64KB+16KB of data TCM RAM without problems of the conflict with L1-cache.

Second question. Address DTCM-RAM 0x20000000 + 64 Kbytes, and ITCM-RAM 0x0 + 16 Kbytes. The address space of memory from 0x20000000 turns out the linear. For an acceleration of data I just need to declare sections in duplicate: the first set of sections - fast memory, the second - a standard set of sections. If data for the first set appear less than the extent of fast memory - that the standard set will have the partial acceleration. I already checked it, works.

But there was ITCM-RAM use problem.

I want to transfer the table of vectors to fast memory. Where it is possible to execute copying?

Third question.

In case of switching on of the microprocessor there is the hardware reading two 32b words - 1 address of a stack (_estack), the 2nd address of function of reset (Reset_Handler). Filling of the register with the address of a stack - harmless operation. Before the first interruption it is possible to change this address as will take in head.

But function of reset has unique value. I can't assign directly the address from the ITCM-RAM area, there during cold start is empty.

Means to me it is necessary to execute copying of data, a program code, and the table of vectors. And after to execute change of field of loading through structure of SCB.

There is a problem. How to explain to a work environment of GCC - that the residential address changes?

I can execute compilation and assembly of the project with different conditions 2 times. But it is difficult and a little effective. I want that it worked.

I looked for examples of use of TCM-RAM. But nothing good was succeeded to find.

I can print in Russian, so there are less losses.

#stm32f7-memory-tcm*
6 REPLIES 6
AVI-crak
Senior
Posted on May 14, 2017 at 21:47

The question has a tag - special cruelty.

Nesrine M_O
Lead II
Posted on May 15, 2017 at 10:59

Hi

AVI_crak.videocrak

,

-Nesrine-

Posted on May 15, 2017 at 11:05

Hi Nesrine,

Can you please push the web crew to add AN4667 you mention above to the individual 'F7xx pages? I checked only one

http://www.st.com/en/microcontrollers/stm32f746zg.html

  but I could not find it there.

[EDIT] it's not in the

http://www.st.com/content/st_com/en/support/resources/resource-selector.html?querycriteria=productId=SS1858$$resourceCategory=technical_literature$$resourceType=application_note

either.

Thanks,

Jan

Posted on May 15, 2017 at 11:38

Hi

Waclawek.Jan

,

The

AN4667 application note is part of

software expansion for STM32Cube, so you find it under

Tools and Software > EMBEDDED SOFTWARE

of

F7xx pages:

0690X000006070gQAA.png

-Nesrine-

Posted on May 15, 2017 at 11:45

Nesrine,

Yes I saw that. But that appnote contains general information pertaining to the 'F7 more than to Cube/MX, and there's a lack of such information in the appnotes offered in those places. I am not interested in Cube/MX and I am not the only one.

So, let me rephrase: please provide this or similar appnote in the basic 'F7 resources.

Thanks,

Jan

Posted on May 15, 2017 at 12:03

Hi

Waclawek.Jan

I will raise your request internally for checking, and I will come back to you when I could get some updated info.

-Nesrine-