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PUrsu.1
Associate III
February 17, 2023
Question

STM32H723 RAM configuration

  • February 17, 2023
  • 4 replies
  • 3174 views

Hey there,

I am trying to replace an STM32F767 with an H723ZGT Nucleo Board. The projects uses a lot of heap - in the predefined memory configuration there is not enough place in the RAM_D1 sector. What do I need to do for changing the available RAM size for the heap?

This is the default configuration:

/*
******************************************************************************
**
** File : LinkerScript.ld
**
** Author : STM32CubeIDE
**
** Abstract : Linker script for STM32H7 series
** 1024Kbytes FLASH and 560Kbytes RAM
**
** Set heap size, stack size and stack location according
** to application requirements.
**
** Set memory bank area and size if external memory is used.
**
** Target : STMicroelectronics STM32
**
** Distribution: The file is distributed as is, without any warranty
** of any kind.
**
*****************************************************************************
** @attention
**
** Copyright (c) 2022 STMicroelectronics.
** All rights reserved.
**
** This software is licensed under terms that can be found in the LICENSE file
** in the root directory of this software component.
** If no LICENSE file comes with this software, it is provided AS-IS.
**
****************************************************************************
*/
 
/* 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 = 0x200 ; /* required amount of heap */
_Min_Stack_Size = 0x400 ; /* required amount of stack */
 
/* Specify the memory areas */
MEMORY
{
 ITCMRAM (xrw) : ORIGIN = 0x00000000, LENGTH = 64K
 DTCMRAM (xrw) : ORIGIN = 0x20000000, LENGTH = 128K
 FLASH (rx) : ORIGIN = 0x08000000, LENGTH = 1024K
 RAM_D1 (xrw) : ORIGIN = 0x24000000, LENGTH = 320K
 RAM_D2 (xrw) : ORIGIN = 0x30000000, LENGTH = 32K
 RAM_D3 (xrw) : ORIGIN = 0x38000000, LENGTH = 16K
}
 
/* Define output sections */
SECTIONS
{
 /* The startup code goes first into FLASH */
 .isr_vector :
 {
 . = ALIGN(4);
 KEEP(*(.isr_vector)) /* Startup code */
 . = ALIGN(4);
 } >FLASH
 
 /* The program code and other data goes into FLASH */
 .text :
 {
 . = ALIGN(4);
 *(.text) /* .text sections (code) */
 *(.text*) /* .text* sections (code) */
 *(.glue_7) /* glue arm to thumb code */
 *(.glue_7t) /* glue thumb to arm code */
 *(.eh_frame)
 
 KEEP (*(.init))
 KEEP (*(.fini))
 
 . = ALIGN(4);
 _etext = .; /* define a global symbols at end of code */
 } >FLASH
 
 /* Constant data goes into FLASH */
 .rodata :
 {
 . = ALIGN(4);
 *(.rodata) /* .rodata sections (constants, strings, etc.) */
 *(.rodata*) /* .rodata* sections (constants, strings, etc.) */
 . = ALIGN(4);
 } >FLASH
 
 .ARM.extab : { *(.ARM.extab* .gnu.linkonce.armextab.*) } >FLASH
 .ARM : {
 __exidx_start = .;
 *(.ARM.exidx*)
 __exidx_end = .;
 } >FLASH
 
 .preinit_array :
 {
 PROVIDE_HIDDEN (__preinit_array_start = .);
 KEEP (*(.preinit_array*))
 PROVIDE_HIDDEN (__preinit_array_end = .);
 } >FLASH
 
 .init_array :
 {
 PROVIDE_HIDDEN (__init_array_start = .);
 KEEP (*(SORT(.init_array.*)))
 KEEP (*(.init_array*))
 PROVIDE_HIDDEN (__init_array_end = .);
 } >FLASH
 
 .fini_array :
 {
 PROVIDE_HIDDEN (__fini_array_start = .);
 KEEP (*(SORT(.fini_array.*)))
 KEEP (*(.fini_array*))
 PROVIDE_HIDDEN (__fini_array_end = .);
 } >FLASH
 
 /* used by the startup to initialize data */
 _sidata = LOADADDR(.data);
 
 /* Initialized data sections goes into RAM, load LMA copy after code */
 .data :
 {
 . = ALIGN(4);
 _sdata = .; /* create a global symbol at data start */
 *(.data) /* .data sections */
 *(.data*) /* .data* sections */
 *(.RamFunc) /* .RamFunc sections */
 *(.RamFunc*) /* .RamFunc* sections */
 
 . = ALIGN(4);
 _edata = .; /* define a global symbol at data end */
 } >RAM_D1 AT> FLASH
 
 /* Uninitialized data section */
 . = ALIGN(4);
 .bss :
 {
 /* This is used by the startup in order to initialize the .bss section */
 _sbss = .; /* define a global symbol at bss start */
 __bss_start__ = _sbss;
 *(.bss)
 *(.bss*)
 *(COMMON)
 
 . = ALIGN(4);
 _ebss = .; /* define a global symbol at bss end */
 __bss_end__ = _ebss;
 } >RAM_D1
 
 /* 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_D1
 
 /* Remove information from the standard libraries */
 /DISCARD/ :
 {
 libc.a ( * )
 libm.a ( * )
 libgcc.a ( * )
 }
 
 .ARM.attributes 0 : { *(.ARM.attributes) }
}

Thank you all in advance for trying to help me - now I just need a solution but in the near future I need to work on my knowledge regarding memory management.

This topic has been closed for replies.

4 replies

Tesla DeLorean
Guru
February 17, 2023

>>The projects uses a lot of heap - in the predefined memory configuration there is not enough place in the RAM_D1 sector.

How much, and where's it going to come from? The NUCLEO doesn't have SDRAM

The ST GNU/GCC implementation doesn't really allow for pools in different/multiple regions.

Check the _sbrk() implementation, usually in syscalls or newlib

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PUrsu.1
PUrsu.1Author
Associate III
February 17, 2023

I already thought that pools over multiple regions are not that easy. In general I need to store various data structs and FreeRTOS has a TOTAL_HEAPSIZE of 250.000.

Tesla DeLorean
Guru
February 17, 2023

The largest contiguous block of RAM is 320KB

What you might want to do is direct other usages over into the 64KB (ITCM), 128KB (DTCM), 32KB (SRAM1+SRAM2) or 16KB (SRAM4) sections

Use the __attribute__ directive.

You'll have to probably rework the startup.s code to initialize things.

You might be able to simplify this by having just the HEAP/STACK in the 320KB region, and having everything else in the DTCMRAM 128KB

Keil manages the initialization better via tables, as does ARDUINO/GCC, and Keil I can push memory regions into the heap's block list.

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