MSP432 Custom Bootloader

Josh Adler2

Is there any example code available for a custom bootloader for the MSP432?

I am looking for the code that prepares the micro and then jumps to the main program (say, defined at 0x8000).

I assume you need to set the interrupt vector table location and jump to the new start location? How is this best achieved?

over 9 years ago

0 DavidL over 9 years ago

TI__Mastermind 25045 points

Hi Josh,

I have been working on a similar example code.

Josh Adler2 said:
I assume you need to set the interrupt vector table location and jump to the new start location? How is this best achieved?

Yes that is correct and I do not have any problem sharing these projects, but before doing that, which IDE (CCS/IAR/KEIL) are you using??

Regards,

David

0 Josh Adler2 over 9 years ago in reply to DavidL

Intellectual 400 points

Hi David,

I am using CCS 6.1. I tried to click on the image, but I get access denied.

Regards,

Josh

0 DavidL over 9 years ago in reply to Josh Adler2

TI__Mastermind 25045 points

Hi Josh,

I just updated the image. I'll try to have the example projects by tomorrow.

Thanks,

David

0 Josh Adler2 over 9 years ago in reply to DavidL

Intellectual 400 points

Thanks David.

I think I have it sorted, I have my cmd files with App1 at 0x0000 and App2 at 0x8000,

then in App1's CMD file:

--retain=interruptVectors
--retain=flashMailbox

MEMORY
{
    FLASH_BOOT (RX) : origin = 0x00000000, length = 0x00008000
    FLASH     (RX) : origin = 0x00008000, length = 0x00038000
    FLASH_OTP (RX) : origin = 0x00200000, length = 0x00004000
    SRAM      (RWX): origin = 0x20000000, length = 0x00010000
}

/* The following command line options are set as part of the CCS project.    */
/* If you are building using the command line, or for some reason want to    */
/* define them here, you can uncomment and modify these lines as needed.     */
/* If you are using CCS for building, it is probably better to make any such */
/* modifications in your CCS project and leave this file alone.              */
/*                                                                           */
/* --heap_size=0                                                             */
/* --stack_size=512                                                          */
/* --library=rtsv7M4_T_le_eabi.lib                                           */

/* Section allocation in memory */

SECTIONS
{
    .intvecs:   > 0x00000000
    .text   :   > FLASH_BOOT
    .const  :   > FLASH_BOOT
    .cinit  :   > FLASH_BOOT
    .pinit  :   > FLASH_BOOT

    .flashMailbox : > 0x00202000

    .vtable :   > 0x20000000
    .data   :   > SRAM
    .bss    :   > SRAM
    .sysmem :   > SRAM
    .stack  :   > SRAM (HIGH)
    //.stack  :   > SRAM (HIGH), fill = 0xCDCDCDCD
}

And App1's code:

{

  SCB->VTOR = 0x8000;

  //
  // Load the stack pointer from the application's vector table.
  //
  __asm("    ldr     r1, [r0, #0]\n"
      "    mov     sp, r1\n");

  //
  // Load the initial PC from the application's vector table and branch to
  // the application's entry point.
  //
  __asm("    ldr     r0, [r0, #4]\n"
      "    blx      r0\n");

App2's CMD File

--retain=interruptVectors
--retain=flashMailbox

MEMORY
{
    FLASH_BOOT (RX) : origin = 0x00000000, length = 0x00008000
    FLASH     (RX) : origin = 0x00008000, length = 0x00038000
    FLASH_OTP (RX) : origin = 0x00200000, length = 0x00004000
    SRAM      (RWX): origin = 0x20000000, length = 0x00010000
}

/* The following command line options are set as part of the CCS project.    */
/* If you are building using the command line, or for some reason want to    */
/* define them here, you can uncomment and modify these lines as needed.     */
/* If you are using CCS for building, it is probably better to make any such */
/* modifications in your CCS project and leave this file alone.              */
/*                                                                           */
/* --heap_size=0                                                             */
/* --stack_size=512                                                          */
/* --library=rtsv7M4_T_le_eabi.lib                                           */

/* Section allocation in memory */

SECTIONS
{
    .intvecs:   > 0x00008000
    .text   :   > FLASH
    .const  :   > FLASH
    .cinit  :   > FLASH
    .pinit  :   > FLASH

    .flashMailbox : > 0x00202000

    .vtable :   > 0x20000000
    .data   :   > SRAM
    .bss    :   > SRAM
    .sysmem :   > SRAM
    .stack  :   > SRAM (HIGH)
    //.stack  :   > SRAM (HIGH), fill = 0xCDCDCDCD
}

Anything missing? Seems to work as expected, just not sure about the loading of the VTOR register.

Regards,

Josh

0 DavidL over 9 years ago in reply to Josh Adler2

TI__Mastermind 25045 points

Hi Josh,

That's exactly how I did it. The only difference is that for VTOR, I used the "interruptVectors" (msp432_startup_ccs.c) instead of the address. Something like this:

SCB->VTOR = (uint32_t)interruptVectors;

Hopefully this helps.

David

0 Josh Adler2 over 9 years ago in reply to DavidL

Intellectual 400 points

Hi David,

Won't that be the interruptVectors for the current application (bootloader) instead of the application you are calling (main code)?

/* Interrupt vector table.  Note that the proper constructs must be placed on this to */
/* ensure that it ends up at physical address 0x0000.0000 or at the start of          */
/* the program if located at a start address other than 0.                            */
#pragma RETAIN(interruptVectors)
#pragma DATA_SECTION(interruptVectors, ".intvecs")
void (* const interruptVectors[])(void) =
{
    (void (*)(void))((uint32_t)&__STACK_END),
                                            /* The initial stack pointer */
    resetISR,                               /* The reset handler         */
...
...
    defaultISR                              /* Reserved 63               */
};

Josh

0 DavidL over 9 years ago in reply to Josh Adler2

TI__Mastermind 25045 points

Hi Josh,

I believe it should depend on who (application or boot loader) is writing to the SCB->VTOR register. In my case the boot loader passes the control to the application who actually writes to the SCB->VTOR register.

Hopefully this helps.

David

0 Josh Adler2 over 9 years ago in reply to DavidL

Intellectual 400 points

Hi David,

That sounds sensible, but I do it in the bootloader in order to determine the reset vector address so the bootloader knows where to jump. How do you do that part without setting VTOR?

  SCB->VTOR = 0x8000;

  //
  // Load the stack pointer from the application's vector table.
  //
  __asm("    ldr     r1, [r0, #0]\n"
      "    mov     sp, r1\n");

  //
  // Load the initial PC from the application's vector table and branch to
  // the application's entry point.
  //
  __asm("    ldr     r0, [r0, #4]\n"
      "    blx      r0\n");

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MSP432 Custom Bootloader