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Hands-on: ISR in ICTM

Introduction

  • According to Reference Manual of STM746, we can put execution code into ITCM RAM (16MB):

  • The following cases will be covered in this hands-on by three different "Build Configurations":

    1. Single ISR in ITCM

    2. Single ISR along with vector table in ITCM

    3. All ISRs in stm32f7xx_it along with vector table in ITCM

Case 1: Single ISR (SysTick_Handler) in ITCM

  1. Add new build configuration for case 1:

    • Right click on project icon and then select "Build Configurations --> Manage":

    • Press "New..." button:

    • Type in "case 1" in Name and then press "OK" button:

    • Select case 1 and then press "Set Active" button:

    • Press "OK" button to finish setting up new build configuration:

  2. Manage stm32f7xx_it.c

    • Rename the original stm32f7xx_it.c to stm32f7xx_it_case1.c

    • Add __attribute__((section())) in front of SysTick_Handler(void) in stm32f7xx_it_case1.c as shown below:

      __attribute__((section(".itcmram"))) void SysTick_Handler(void)
{
  ...
}

  3. Manage startup_stm32f746nghx.s

    • Copy reference startup_stm32f746nghx_case1.s and paste it to Startup folder in Project Explorer

    • Exclude original startup_stm32f746nghx.s:

      • Right clock on startup_stm32f746nghx.s and then select "Properties":
      • Check "Exclude resource from build" as shown below:

  4. Manage system_stm32f7xx.c:

    • Copy system_stm32f7xx.c and paste it in Project Explorer and then rename it to system_stm32f7xx_case1.c

  5. Manage STM32F746NGHX_FLASH.ld:

    • Rename STM32F746NGHX_FLASH.ld in Project Explorer to STM32F746NGHX_FLASH_case1.ld.

    • Add the following section .itcmram definition into linker script STM32F746NGHX_FLASH_case1.ld between .data and .fini_array sections:

           .itcmram :
     {
       . = ALIGN(4);
       _sitcmram = .;       /* create a global symbol at ccmram start */
       *(.itcmram)
  
       . = ALIGN(4);
       _eitcmram = .;       /* create a global symbol at ccmram end */
     } >ITCMRAM AT> FLASH

    • Setup linker:

      • Right click on project icon and then select "Properties":

      • Set correct name of linker script and then press "Apply and Close" button as shown below:

  6. Before building the project, please check again the following files are correctly placed in your Project Explorer:

    • Src\stm32f7xx_it_case1.c
    • Src\system_stm32f7xx_case1.c
    • Startup\startup_stm32f746nghx_case1.s
    • STM32F746NGHX_FLASH_case1.ld

  7. After building project, SysTick_Handler is in section .itcmram which is located in ITCMRAM memory region by checking Build Analyzer as shown below:

  8. After starting debug session, set a breakpoint in SysTick_Handler() and then press "RESUME" button and then code stops at the breakpoint:

Case 2: Single ISR (SysTick_Handler) along with vector table in ITCM

  1. Please follow case 1 to add new build configuration for case 2.

  2. Manage stm32f7xx_it.c

    • Copy stm32f7xx_it_case1.c under Src folder in Project Explorer, paste it in the same folder and then rename it to stm32f7xx_it_case2.c

    • Exclude stm32f7xx_it_case1.c.

  3. Manage startup_stm32f746nghx.s

    • Copy reference startup_stm32f746nghx_case2.s and paste it to Startup folder in Project Explorer.

    • Exclude original startup_stm32f746nghx_case1.s.

  4. Manage system_stm32f7xx.c

    • Copy system_stm32f7xx_case1.c and paste it in Project Explorer and then rename it to system_stm32f7xx_case2.c

    • Exclude system_stm32f7xx_case1.c.

    • Change VTOR setting:

      SCB->VTOR = 0x00000000;

  5. Manage STM32F746NGHX_FLASH.ld:

    • Copy and paste STM32F746NGHX_FLASH_case1.ld in Project Explorer and rename the copied file to STM32F746NGHX_FLASH_case2.ld.

    • Add the following section .itcmram definition into linker script STM32F746NGHX_FLASH_case2.ld between .data and .fini_array sections:

           .itcmram :
     {
       . = ALIGN(4);
       _sitcmram = .;       /* create a global symbol at ccmram start */
       *(.isr_vector_itcm)
       *(.itcmram)
  
       KEEP(*(.isr_vector_itcm .itcmram))
    
       . = ALIGN(4);
       _eitcmram = .;       /* create a global symbol at ccmram end */
     } >ITCMRAM AT> FLASH

    • Setup linker:

      • Right click on project icon and then select "Properties":

      • Set correct name of linker script and then press "Apply and Close" button as shown below:

  6. Before building the project, please check again the following files are correctly placed in your Project Explorer:

    • Src\stm32f7xx_it_case2.c
    • Src\system_stm32f7xx_case2.c
    • Startup\startup_stm32f746nghx_case2.s
    • STM32F746NGHX_FLASH_case2.ld

  7. After building project, SysTick_Handler and 2nd vector table (g_pfnVectors_itcm) are placed in section .itcmram which is located in ITCMRAM memory region by checking Build Analyzer as shown below:

  8. After starting debug session, set a breakpoint in SysTick_Handler() and then press "RESUME" button and then code stops at the breakpoint:

  • SysTick_Handler is executed without error.
  • From "Memo View", 2nd vector table is placed correctly.

Case 3: All ISRs in stm32f7xx_it along with vector table in ITCM

  1. Please follow case 1 and 2 to add new build configuration for case 3.

  2. Manage stm32f7xx_it.c

    • Copy stm32f7xx_it_case2.c under Src folder in Project Explorer, paste it in the same folder and then rename it to stm32f7xx_it_case3.c

    • Exclude stm32f7xx_it_case2.c.

    • Remove __attribute__((section())) in front of SysTick_Handler():

      void SysTick_Handler(void)
{
  ...
}

  3. Manage startup_stm32f746nghx.s

    • Copy reference startup_stm32f746nghx_case3.s and paste it to Startup folder in Project Explorer.
    • Exclude startup_stm32f746nghx_case2.s.

  4. Manage system_stm32f7xx.c

    • Copy system_stm32f7xx_case2.c and paste it in Project Explorer and then rename it to system_stm32f7xx_case3.c

    • Exclude system_stm32f7xx_case2.c.

  5. Manage STM32F746NGHX_FLASH.ld:

    • Copy and paste STM32F746NGHX_FLASH_case2.ld in Project Explorer and rename the copied file to STM32F746NGHX_FLASH_case3.ld.

    • Add the following section .itcmram definition into linker script STM32F746NGHX_FLASH_case3.ld between .data and .fini_array sections:

      • .text section:

        .text :
  {
    . = ALIGN(4);
    /**(.text)     */      /* .text sections (code) */
    /**(.text*)    */      /* .text* sections (code) */
    
    *(EXCLUDE_FILE (*stm32f7xx_it_config3.o) .text)           
    *(EXCLUDE_FILE (*stm32f7xx_it_config3.o) .text*)           
    
    *(.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

      • .itcmram section:

          .itcmram :
  {
    . = ALIGN(4);
    _sitcmram = .;       /* create a global symbol at ccmram start */
    *(.isr_vector_itcm)
    *stm32f7xx_it_case3.o (.text .text*)
    *(.itcmram)

    KEEP(*(.isr_vector_itcm .itcmram))
 
    . = ALIGN(4);
    _eitcmram = .;       /* create a global symbol at ccmram end */
  } >ITCMRAM AT> FLASH

    • Setup linker:

      • Right click on project icon and then select "Properties":
      • Set correct name of linker script and then press "Apply and Close" button as shown below:

  6. Before building the project, please check again the following files are correctly placed in your Project Explorer:

    • Src\stm32f7xx_it_case3.c
    • Src\system_stm32f7xx_case3.c
    • Startup\startup_stm32f746nghx_case3.s
    • STM32F746NGHX_FLASH_case3.ld

  7. After building project, all interrupt handlers and 2nd vector table (g_pfnVectors_itcm) are placed in section .itcmram which is located in ITCMRAM memory region by checking Build Analyzer as shown below:

  8. After starting debug session, set a breakpoint in SysTick_Handler() and then press "RESUME" button and then code stops at the breakpoint:

    • __attribute__((section())) is not used for all interrupt handlers.
    • SysTick_Handler() is executed correctly.
    • From "Memo View", 2nd vector table is placed in ICTM correctly.