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How to implement and use your own external flash loader: An example using STM32U5A9J-DK

KDJEM.1
ST Employee

on ‎2024-01-11 02:19 AM - edited on ‎2024-06-18 01:00 AM by Community manager

Introduction 

The main objective of this article is to provide a step-by-step guide on how to develop and add your own external loader to manage external memories. This demo implementation uses a STM32U5A9J-DK and octo-SPI interface, but it can be easily tailored for other microcontrollers and memory types. Thanks to the external loader feature in STM32CubeProgrammer, it is possible to have a direct access to external memories.

1. Prerequisites

Hardware:

  • Micro USB cable to power and program the board
  • STM32U5A9J-DK

KDJEM1_0-1697032362524.png

Software:

  • IAR
  • STM32CubeIDE
  • STM32CubeProgrammer

2. Steps

In section 2.1 below, the method of handling files is described in depth.
If you want to have the results of the edited files at hand immediately, then you can download the extractable file attached at the bottom of the article and skip to section 2.2. 
 

2.1 Develop and add your own External Loader

  • Download an existing external loader project from GitHub. You get the zip file stm32-external-loader-main.zip that you can extract locally
  • Create an “MX25UM51245G_STM32U5A9-DK” folder under "stm32-external-loader-main\STM32U5x_boards"
  • Copy the content of the "stm32-external-loader-main\STM32U5x_boards\MX25LM51245G_STM32U575I-EVAL" folder under the created folder “MX25UM51245G_STM32U5A9-DK”
  • Update drivers
    - Remove all the header files located under "MX25UM51245G_STM32U5A9-DK\Includes\Library"
    - Remove all the .c files located under "MX25UM51245G_STM32U5A9-DK\Sources\Library"
    - Add files:
    File name Source Destination
    stm32u5xx_hal.h

    Repository\STM32Cube_FW_U5_V1.3.0\

    Drivers\STM32U5xx_HAL_Driver\Inc

    		MX25UM51245G_
    STM32U5A9-DK\Includes\Library
    stm32u5xx_hal_cortex.h 
    stm32u5xx_hal_def.h
    stm32u5xx_dma.h
    stm32u5_dma.exe.h
    stm32u5xx_hal_flash.h
    stm32u5xx_hal_flash_ex.h
    stm32u5xx_hal_gpio.h
    stm32u5xx_hal_gpio_ex.h
    stm32u5xx_hal_ospi.h
    stm32u5xx_hal_pwr.h
    stm32u5xx_hal_pwr_ex.h
    stm32u5xx_hal_rcc_ex.h
    stm32u5xx_hal_rcc.h
    stm32u5xx_hal_xspi.h
    stm32u5xx_hal_gfxtim.h
    stm32u5xx_ll_dlyb.h
    stm32u5x9j_discovery.h

    Repository\STM32Cube_FW_U5_V1.3.0\

    Drivers\BSP\STM32U5x9J-DK 

    		 MX25UM51245G_
    STM32U5A9-DK\Includes\Library
    stm32u5x9j_discovery_bus.h
    stm32u5x9j_discovery_conf_template.h
    stm32u5x9j_discovery_errno.h
    stm32u5x9j_discovery_ospi.h
    mx25um51245g.h

    Repository\STM32Cube_FW_U5_V1.3.0\

    Drivers\BSP\Components\mx25um51245g 

    		 MX25UM51245G_
    STM32U5A9-DK\Includes\Library.
    mx25um51245g_conf_template.h
    stm32u5a9xx.h

    Repository\STM32Cube_FW_U5_V1.3.0\

    Drivers\CMSIS\Device\ST\
    STM32U5xx\Include

    		 MX25UM51245G_
    STM32U5A9-DK\Includes\Library
    stm32u5xx.h
    system_stm32u5xx.h
    stm32u5xx_hal.c

    Repository\STM32Cube_FW_U5_V1.3.0\

    Drivers\STM32U5xx_HAL_Driver\Src 

    		 MX25UM51245G_
    STM32U5A9-DK\Sources\Library
    stm32u5xx_hal_cortex.c
    stm32u5xx_hal_dma.c
    stm32u5xx_hal_dma_ex.c
    stm32u5xx_hal_flash.c
    stm32u5xx_hal_flash_ex.c
    stm32u5xx_hal_gpio.c
    stm32u5xx_hal_ospi.c
    stm32u5xx_hal_pwr.c
    stm32u5xx_hal_pwr_ex.c
    stm32u5xx_hal_rcc.c
    stm32u5xx_hal_rcc_ex.c
    stm32u5xx_hal_xspi.c
    stm32u5xx_ll_dlyb.c
    stm32u5x9j_discovery.c 

    Repository\STM32Cube_FW_U5_V1.3.0\

    Drivers\BSP\STM32U5x9J-DK 

    		 MX25UM51245G_
    STM32U5A9-DK\Sources\Library
    stm32u5x9j_discovery_bus.c
    stm32u5x9j_discovery_ospi.c
    mx25um51245g.c

    Repository\STM32Cube_FW_U5_V1.3.0\

    Drivers\BSP\Components\mx25um51245g 

    		 MX25UM51245G_
    STM32U5A9-DK\Sources\Library
    system_stm32u5xx.c file

    Repository\STM32Cube_FW_U5_V1.3.0\

    Drivers\CMSIS\Device\ST\
    STM32U5xx\Source\Templates 

    		 MX25UM51245G_
    STM32U5A9-DK\Sources\Library

    - Rename files:
    Old file name New file name Location 
    stm32u5x9j_discovery_hal_conf_template.h stm32u5x9j_discovery_hal_conf.h MX25UM51245G_
    STM32U5A9-DK\Includes\Library
    mx25um51245g_conf_template.h mx25um51245g_conf.h MX25UM51245G_
    STM32U5A9-DK\Includes\Library

    - Edit files:
    File  Location Modification
    stm32u5xx_hal.h MX25UM51245G_STM32U5A9-DK\Includes\Library Change #include "stm32u5xx_hal_conf.h"
    by
    #include "stm32u5xx_hal_conf_template.h"
    stm32u5xx_hal_gfxtim.h MX25UM51245G_STM32U5A9-DK\Includes\Library Comment " GFXTIM_TypeDef   *Instance; "
    mx25um51245g_conf.h MX25UM51245G_STM32U5A9-DK\Includes\Library

    Delete #include "stm32xxxx_hal.h"

    Add:

    #include "stm32u5xx.h" 

    #include "stm32u5xx_hal.h"
    stm32u5xx.h MX25UM51245G_STM32U5A9-DK\Includes\Library Uncomment "#define STM32U5A9xx"
    stm32u5x9j_discovery_ospi.h MX25UM51245G_STM32U5A9-DK\Includes\Library Change #include "../Components/mx25um51245g/mx25um51245g.h" by #include "mx25um51245g.h"

    Ensure the following:
    The MX25UM5124G_STM32U5A9-DK\Includes\Library folder must contain these headers as shown in the below figure:
    KDJEM1_0-1697201124674.png

    The MX25UM5124G_STM32U5A9-DK\Sources\Library folder must contain these headers as shown in the below figure.
    KDJEM1_2-1697201270111.png

Update loader source files

2.1.1 Edit Dev_Inf.c file

The purpose is to modify MX25UM51245G_STM32U5A9-DK\Sources\Loader\ Dev_Inf.c to support MX25UM51245G memory and STM32U5A9-DK board. For more information, refer to the memory MX25UM51245G datasheet and UM2967. 

It is described in the datasheet, that MX25UM51245G is 512 Mbit octal interface serial NOR_Flash memory. In this case, the device type is "NOR_FLASH" with "Device Size 512 Mbit = 64 Mbytes = 0x4000000".

It is also mentioned in the memory datasheet that the "programming page size" is "256 bytes=0x100" and the "sector size" is "64 Kbytes=0x00010000". 
In this case the memory has "1024 Sectors=0x00000400". You can find these details in the memory datasheet section 1. FEATURES. 

The UM2967 states that MX25UM5124GXDIOO memory is connected to OCTOSPI1, so the "Device start address" is "0x90000000."
In conclusion, you can modify the Dev_Inf.c as shown below: 

 

 

MX25UM51245G_STM32U5A9J-DK", 	 					// Device Name + Discovery Board name
   NOR_FLASH,                   					        // Device Type
   0x90000000,                						        // Device Start Address
   0x4000000,              						        // Device Size in 64 MBytes
   0x100,                    						        // Programming Page Size 4096 Bytes
   0xFF,                       						        // Initial Content of Erased Memory
// Specify Size and Address of Sectors (view example below)
   0x00000400, 0x00010000,     				 		        // Sector Num : 1024 ,Sector Size: 64 KBytes
   0x00000000, 0x00000000,

 

 

2.1.2 Edit Loader_Src.c file

 

File  Location Modification
Loader_Src.c  MX25UM51245G_STM32U5A9-DK\Sources\Loader Change #include "stm32u575i_eval_ospi.h"  by #include "stm32u5x9j_discovery_ospi.h"
Change “BSP_OSPI_NOR_Erase_Block(0,BlockAddr,  MX25LM51245G_ERASE_64K);” by “BSP_OSPI_NOR_Erase_Block(0,BlockAddr,  MX25UM51245G_ERASE_64K);
Add Delay(*) in private Function 
void HAL_Delay(uint32_t Delay)
{
  int i=0;
  for (i=0; i<0x1000; i++);
}​​

* This delay is necessary for read and write operations (refer to the memory datasheet).

  • Update the MX25UM51245G_STM32U5A9_DK project properties
  • Rename the following files:
Old file name New file name Location 
MX25LM512G_STM32U575I-EVAL.eww MX25UM512G_STM32U5A9-DK.eww MX25UM5124G_STM32U5A9-DK\Project\EWARM
MX25LM512G_STM32U575I-EVAL.ewp MX25UM51245G_STM32U5A9_DK.ewp MX25UM5124G_STM32U5A9-DK\Project\EWARM
  • Edit files:
File  Location Modification
MX25UM512G_STM32U5A9-DK.eww" MX25UM512G_STM32U5A9-DK.ewwMX25UM5124G_
STM32U5A9-DK\Project\EWARM		 Change " <path>$WS_DIR$\MX25LM51245G_STM32U575_EVAL.ewp</path>" by"  <path>$WS_DIR$\MX25UM51245G_STM32U5A9_DK.ewp</path>"
  • Open MX25LM1245G_STM32U575I-EVAL.eww project in MX25UM51245G_STM32U5A9-DK\ Project\EWARM with the IAR toolchain
  • Select all sources files in library then click right and remove them as shown in the figure below:
    KDJEM1_0-1697472177198.png
  • Right click on Library -> Add -> Add Files, select all source files available under MX25UM51245G_STM32U5A9-DK\Sources\Library\
    KDJEM1_1-1697472261252.png
  • Right click in the project then select "options" and add the include path:
    "$PROJ_DIR$\..\..\Includes\CMSIS"
    "$PROJ_DIR$\..\..\Includes\Library"
    "$PROJ_DIR$\..\..\Includes\Loader"
    "$PROJ_DIR$\..\..\..\..\..\..\STM32Cube\Repository\STM32Cube_FW_U5_V1.3.0\Drivers\STM32U5xx_HAL_Driver\Inc" 

    KDJEM1_2-1697472478030.png

    KDJEM1_3-1697472676572.png

  • Modify the output name:
    KDJEM1_1-1702051824145.png
  • Build the project and make sure that the built is succeeded with 0 error and warnings. An MX25UM5124G_STM32U5A9J-DK.stldr is created in the output. 
    KDJEM1_6-1697472858329.png

  • Add the created external loader to STM32CubeProgrammer
    File name Source Destination
    MX25UM5124G_STM32U5A9J-DK.stldr MX25UM5124G_STM32U5A9-DK\Project\EWARM\Debug\Exe Program Files\STMicroelectronics\
    STM32Cube\
    STM32CubeProgrammer
    \bin\ExternalLoader

2.1.3 Verify your External Loader using the STM32CubeProgrammer

  1. Open GPIO_IOToggle example from \Repository\STM32Cube_FW_U5_V1.3.0\Projects\STM32U5x9J-DK\Examples\GPIO\GPIO_IOToggle using STM32CubeIDE as shown in the below figure:

    KDJEM1_0-1702052241803.png

  2. Right-click the CPIO_IOToggle project to modify its properties

    KDJEM1_1-1697040592272.png

     

  3.  Select "Convert to binary file(-O binary)" to create a binary file as shown in the figure belowKDJEM1_3-1697038936824.png

  4. Click to Debug  KDJEM1_4-1697038963219.png then click toKDJEM1_5-1697038963220.png

  5. Open STM32CubeProgrammer and click to External loaders, select MX25UM5124G_STM32U5A9J-DK.stldr and click to connect as in the figure below

    KDJEM1_10-1697039694300.png

  6. Click on the icon "Erasing & programming":
    Browse to the GPIO_IOToggle.bin binary created previously.
    KDJEM1_7-1697039280926.png

    Choose the "Start address" 0x90000000 and select "Verify programming" to verify the download.
    Click on "Start Programming".
    KDJEM1_3-1697201607326.png
    Please make sure that the download verified successfully.

  7. Click button reset and you can see LD3 and LD4 toggling.

  8. Go to "Memory & File editing" and verify the same data output in 0x08000000 and in 0x90000000.

    KDJEM1_5-1697201727865.png


KDJEM1_6-1697201784087.png

After following this guide, you should now be able to implement and use your own external flash loader. If you encounter any issues, we suggest that you create a post in the ST Community for further assistance.

Related links

GitHub: stm32-external-loader
UM2237: User manual - STM32CubeProgrammer software description
UM2967: User manual - discovery kit with STM32U5ANJ MCU
MX25UM51245G datasheet 

MX25UM5124G_STM32U5A9-DK.7z
Version history
Last update:
‎2024-06-18 01:00 AM
Updated by:
Community manager
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