STM32F7 DISCO - memory sections

benny · ‎2015-08-24

Posted on August 24, 2015 at 13:51

Hi all,

I have a question about the different memory sections. I use a modified version of the demonstration project.

There are 4 memory sections:

SRAM

SDRAM

Flash

NOR (QSPI)

This code save the variable to NOR:

#if defined ( __ICCARM__ )

#pragma location=''ExtQSPIFlashSection''

#else

__attribute__((section(''.ExtQSPIFlashSection'')))

#endif

So now my Questions.

1) How do i know where everything else is stored? I think const variables are stored in Flash and everything else in SRAM. But the SRAM-HAL-Header isn't used in this project. So my variables are stored in SDRAM?

2) And what happen if i create a new variable with malloc?

3) There is a function to get the free size of memory?

Thanks everyone!

For ST:

I have 2 wishes for a new Rev. of the STM32F7 DISCO.

- place a empty (header-) connection with a solder bridge to connect a battery for the RTC

- some more empty connections for another ADC (now i can only use ADC 3 over Arduino Pins)

But it's still a great board!

benny · ‎2016-11-24

Posted on November 24, 2016 at 12:28

Finally I get it working. It was realy easy with the help of the new ''Mastering the FreeRTOS Real Time Kernel - A Hands-On Tutorial Guide''.

I don't need to change anything in the startup- or linker-files. Here is what you need to change:

Step 1:

File: LCDconf.c

Change the following two lines:

#define LCD_LAYER0_FRAME_BUFFER ((int)0xC0200000)

#define LCD_LAYER1_FRAME_BUFFER ((int)0xC0400000)

to:

#define LCD_LAYER0_FRAME_BUFFER ((int)0xC0000000)

#define LCD_LAYER1_FRAME_BUFFER ((int)0xC0200000)

This moves the framebuffer to the first 4 MB of the SDRAM.

Step 2:

File: main.c

Add these two defines:

#define SDRAM_HEAP_START_ADDRESS ((uint8_t *) 0x0xC0400000)

#define SDRAM_HEAP_SIZE (4 * 1024 * 1024) // Size is 4 MB

The ucHeap should defined in a normal way or in an extra RAM-section like in the demonstration project:

uint8_t ucHeap[configTOTAL_HEAP_SIZE];

or (e.g.):

uint8_t ucHeap[ configTOTAL_HEAP_SIZE ] __attribute__((section(''.Heap'')));

Now you need to define the heap sections:

const HeapRegion_t xHeapRegions[] =

{

{ ucHeap, configTOTAL_HEAP_SIZE },

{ SDRAM_HEAP_START_ADDRESS, SDRAM_HEAP_SIZE },

{ NULL, 0 } // end mark

};

In your main-function you should initialize the MPU,Cache,HAL,SysCLK first:

(The next example use function names from the domenstartion project)

int main(void) {

MPU_Config();

CPU_CACHE_Enable();

HAL_Init();

SystemClock_Config();

k_BspInit(); // SDRAM is initialized here

vPortDefineHeapRegions(xHeapRegions); // Tell FreeRTOS which memory to use for the Heap

// now any user code or FreeRTOS-related code can start

}

Step 3:

Use heap_5.c from the FreeRTOS!

Finished!

Everything will work fine.

The Linker will check if the Heap fits inside the RAM, but the Linker just use the size which is defined with configTOTAL_HEAP_SIZE. If the heap is getting to large (maybe from malloc()) the FreeRTOS will use the next section which is placed in SDRAM.

I tested pvPortMalloc(), arithmetic operations, string-functions and pointer arithmetic. Everything is okay.

I hope this will help someone :)