SDRAM and a global struct.

[Hector_R]

Hi.

I am using TouchGFX and it works fine,

My MCU is STM32H743

But when I use the SDRAM for other things the code does not work.

My question is:

Can I use struct in the  SDRAM.?

I have this one in my c file.

SD_CARD SdCard __attribute__((section("\"SDCardSection\""))) __attribute__((aligned(4)));

In my h file as follows:

typedef struct {
	char Name[256];
	char Path[1000];
	char File[2000];
	uint8_t LogicalDrive;
}SD_CARD;
extern SD_CARD SdCard __attribute__((section("\"SDCardSection\""))) __attribute__((aligned(4)));

 My Linker file is as follows:

/* Entry Point */
ENTRY(Reset_Handler)

/* Highest address of the user mode stack */
_estack = ORIGIN(RAM_D1) + LENGTH(RAM_D1);    /* end of RAM */
/* Generate a link error if heap and stack don't fit into RAM */
_Min_Heap_Size = 0x400;      /* required amount of heap  */
_Min_Stack_Size = 0x800; /* required amount of stack */

/* Specify the memory areas */
MEMORY
{
  FLASH (rx)     : ORIGIN = 0x08000000, LENGTH = 2048K
  DTCMRAM (xrw)  : ORIGIN = 0x20000000, LENGTH = 128K
  RAM_D1 (xrw)   : ORIGIN = 0x24000000, LENGTH = 512K
  RAM_D2 (xrw)   : ORIGIN = 0x30000000, LENGTH = 288K
  RAM_D3 (xrw)   : ORIGIN = 0x38000000, LENGTH = 64K
  ITCMRAM (xrw)  : ORIGIN = 0x00000000, LENGTH = 64K
  QUADSPI (r)    : ORIGIN = 0x90000000,  LENGTH = 16M
  SDRAM   (xrw)  : ORIGIN = 0xC0000000,  LENGTH = 32M  
}

etc
etc
etc
  .ARM.attributes 0 : { *(.ARM.attributes) }
    
  BufferSection (NOLOAD) :
  {
    *(Video_RGB_Buffer Video_RGB_Buffer.*)
    *(.gnu.linkonce.r.*)
    . = ALIGN(0x4);

    *(TouchGFX_Framebuffer TouchGFX_Framebuffer.*)
    *(.gnu.linkonce.r.*)
    . = ALIGN(0x4);
   } >SDRAM
   
   SDCardSection (NOLOAD) :
  {
    *(SDCardSection SDCardSection .*)
    *(.gnu.linkonce.r.*)
    . = ALIGN(0x4);
   } >SDRAM

 Best Regards.

[GaetanGodart]

Hello @Hector_R and welcome to the community!

I do not see why you could not use a struct in the SDRAM.

I do not think you need 

extern SD_CARD SdCard __attribute__((section("\"SDCardSection\""))) __attribute__((aligned(4)));

 in your header file. Just declare the type in the source file.

Are you able to use your SDRAM when you don't use the structure?

Regards,

[mƎALLEm]

Hello,

You've already declared and relocated it in SDRAM in the c file:

SD_CARD SdCard __attribute__((section("\"SDCardSection\""))) __attribute__((aligned(4)));

No need to relocate it again in the header file: 

typedef struct {
	char Name[256];
	char Path[1000];
	char File[2000];
	uint8_t LogicalDrive;
}SD_CARD;
extern SD_CARD SdCard;

The linker knows by the key "extern" it's the same variable you've declared in .c file.

[Hector_R]

Hello Gaetan.

I need to add the structure as an extern because those variables are used in other files. (from TouchGFX)

This works well.

My .c file.

// My structure
SD_CARD SdCard

In my .h file

typedef struct {
	char Name[256];
	char Path[1000];
	char File[2000];
	uint8_t LogicalDrive;
}SD_CARD;
extern SD_CARD SdCard;

 As you can see when

But I would use the SDRAM  because I need to add big buffers to display files (SD CARD file names)

But this way the display does not work.

typedef struct {
	char Name[256];
	char Path[1000];
	char File[2000];
	uint8_t LogicalDrive;
}SD_CARD;
extern SD_CARD SdCard __attribute__((section("\"SDCardSection\""))) __attribute__((aligned(4)));

[mƎALLEm]

As I said you need to declare and relocate that structure in the c file:

SD_CARD SdCard __attribute__((section("\"SDCardSection\""))) __attribute__((aligned(4)));

Then export it the header file without any relocation:

typedef struct {
	char Name[256];
	char Path[1000];
	char File[2000];
	uint8_t LogicalDrive;
}SD_CARD;
extern SD_CARD SdCard;

[Hector_R]

Hello Friend!.

Yes, I have tested it right now.

But the problem is still there.

If I use a simple buffer it works, for example:

.c file

char SdCard_Name[256] __attribute__((section("\"SDCardSection\""))) __attribute__((aligned(4)));

extern SdCard_Name[256];

[mƎALLEm]

You need to specify what do you mean by "it doesn't work". Struct wrongly filled with incorrect values? not accessible? or what?

[Hector_R]

Hello.

I have done a debug.

When the first MX_TouchGFX_Process(); is called all is corrupted.

  MX_GPIO_Init();
  MX_DMA_Init();
  MX_QUADSPI_Init();
  MX_FMC_Init();
  MX_CRC_Init();
  MX_LTDC_Init();
  MX_DMA2D_Init();
  MX_TIM2_Init();
  MX_SDMMC1_SD_Init();
  MX_FATFS_Init();
  MX_I2S1_Init();
  MX_USART1_UART_Init();
  MX_I2C1_Init();
  MX_USB_HOST_Init();
  MX_TouchGFX_Init();
  /* USER CODE BEGIN 2 */

  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */
    MX_USB_HOST_Process();

  MX_TouchGFX_Process();
    /* USER CODE BEGIN 3 */
  }

I am not using FreeRTOS.

This image shows the display.