Loading...
 

SW4STM32 and SW4Linux fully supports the STM32MP1 asymmetric multicore Cortex/A7+M4 MPUs

   With System Workbench for Linux, Embedded Linux on the STM32MP1 family of MPUs from ST was never as simple to build and maintain, even for newcomers in the Linux world. And, if you install System Workbench for Linux in System Workbench for STM32 you can seamlessly develop and debug asymmetric applications running partly on Linux, partly on the Cortex-M4.
You can get more information from the ac6-tools website and download (registration required) various documents highlighting:

System Workbench for STM32

Forum List Topic List

[ prev topic ]  

Locate Heap in SDRAM

Posted by FranzWegerer on 2016-02-08 13:49

Hello,

I want to locate heap in SDRAM. I found some Keil samples, but ...

SDRAM adress is 0xD0000000, size 8M.

Thanks a lot

Reads: 19197
Link
Posted by tarek bouchkati on 2016-02-08 16:07 Tunisia

Hello Franz,

you need to specify SDRAM memory in your linker file (here I am using a linker for STM32L476RGTx with 1M FLASH and 96K RAM) 

/* Specify the memory areas */
MEMORY
{
FLASH (rx)      : ORIGIN = 0x08000000, LENGTH = 1M
RAM (xrw)       : ORIGIN = 0x20000000, LENGTH = 96K
SDRAM(xrw)    : ORIGIN = 0x????????, LENGTH = 8M
}


And modify >RAM by >SDRAM 

/* User_heap_stack section, used to check that there is enough RAM left */
  ._user_heap_stack :
  {
    . = ALIGN(4);
    PROVIDE ( end = . );
    PROVIDE ( _end = . );
    . = . + _Min_Heap_Size;
    . = . + _Min_Stack_Size;
    . = ALIGN(4);
  } >SDRAM


Update:
Do not forget to initialize you SDRAM before your application starts !
It should be done in Reset Handler (in startup file) in assembly.

There are better solutions that writing in assembler
1- Start with the default STACK&HEAP location (RAM), initialize your SDRAM then switch to SDRAM as STACK&HEAP location
2- Separate Heap and stack locations (STACK in RAM and HEAP in SDRAM) in linker file, than initialize SDRAM in your main before any malloc usage

Link

Posted by FranzWegerer on 2016-02-09 20:26

First - thank you very much!

Yes I want only heap into SDRAM (the heap can use the whole SDRAM), but how can I split this? Sorry, but I am not very familiar with linker scripts

Link
Posted by tarek bouchkati on 2016-02-10 13:37 Tunisia

We can also do that without big modifcations in linker script biggrin

by defining the heap start/end in linker miscellaneous flags, ie : 

-Wl,--defsym=__heap_start=0xD0000000,--defsym=__heap_limit=0xD0800000

Note: you have to change these values with yours

and removing heap informations from linker (not necessary but good for your linker lisibility)

1- remove this line :
_Min_Heap_Size = 0; /* required amount of heap */
2- and replace this 

/* User_heap_stack section, used to check that there is enough RAM left */
  ._user_heap_stack :
  {
    . = ALIGN(8);
    PROVIDE ( end = . );
    PROVIDE ( _end = . );
    . = . + _Min_Heap_Size;
    . = . + _Min_Stack_Size;
    . = ALIGN(8);
  } >RAM

with the following 

/* User_stack section, used to check that there is enough RAM left */
  ._user_stack :
  {
    . = ALIGN(8);
    PROVIDE ( end = . );
    PROVIDE ( _end = . );
    . = . + _Min_Stack_Size;
    . = ALIGN(8);
  } >RAM



Edit: I forgot syscalls modifications mrgreen

You have to add syscalls.c to project (you can borrow it from another SystemWorkbench project)
then replace _sbrk function by the following 

caddr_t _sbrk(int incr)
{
	extern char __heap_start asm("__heap_start"); /* Defined by the linker. */
	extern char __heap_limit asm("__heap_limit"); /* Defined by the linker. */

	static char *heap_end;
    static char *heap_limit = &__heap_limit;

	char *prev_heap_end;

	if (heap_end == 0)
		heap_end = &__heap_start;

	prev_heap_end = heap_end;
	if (heap_end + incr > heap_limit)
	{
		errno = ENOMEM; // not enough memory
		return (caddr_t) -1;
	}

	heap_end += incr;

	return (caddr_t) prev_heap_end;
}
Link

Posted by FranzWegerer on 2016-02-16 15:13

Thanks again. Works without any problems.
I think it is easier to define the symbols in linker script.

Attached the final code with all modifications

code.zip (3.83 Kb)
Link


Posted by Csongor on 2019-09-13 12:12

Hello guys!
I have a similar problem. I want to locate heap in SDRAM in Nucleo144
H743ZI hardware.
Your conversation and solution is very helpfully and interesting, but
i have a lot of question about this topic.

First question:
Can I have to change something in the CubeMX FMC Mode & Configuration
SDRAM 1? Because I don’t realize it is important to me. Nobody speaks
about it. When I was searching on the internet for my problem
solution, I only found about, how to change something in for example:
STM32H743ZITx_FLASH.ld file. You guys are the first solution, who
spoke about it, that I must to change something in the syscall.c file.

Second question:
What is the easiest way to test my SDRAM is working? Nowadays I use malloc function to see this.
Is it correct or do you have any better idea?

Thanks a lot!
Csongor

Link