LPC2368 Secondary Bootloader

[giovannifriolo]

Hi,

I'm developing a secondary bootloader on LPC2368.

The bootloader at startup initialize stack pointer:

....

   LDR     R0, =Top_Stack

#  Enter Undefined Instruction Mode and set its Stack Pointer        

   MSR   CPSR_c, #Mode_UND|I_Bit|F_Bit
   MOV   SP, R0
   SUB   R0, R0, #UND_Stack_Size

#  Enter Abort Mode and set its Stack Pointer

   MSR   CPSR_c, #Mode_ABT|I_Bit|F_Bit
   MOV   SP, R0
   SUB   R0, R0, #ABT_Stack_Size

#  Enter FIQ Mode and set its Stack Pointer

   MSR   CPSR_c, #Mode_FIQ|I_Bit|F_Bit
   MOV   SP, R0
   SUB   R0, R0, #FIQ_Stack_Size

#  Enter IRQ Mode and set its Stack Pointer

   MSR   CPSR_c, #Mode_IRQ|I_Bit|F_Bit
   MOV   SP, R0
   SUB   R0, R0, #IRQ_Stack_Size

#  Enter Supervisor Mode and set its Stack Pointer

   MSR   CPSR_c, #Mode_SVC|I_Bit|F_Bit
   MOV   SP, R0
   SUB   R0, R0, #SVC_Stack_Size

#  Enter User Mode and set its Stack Pointer

   MSR   CPSR_c, #Mode_USR/*|F_Bit                   /* |F_Bit         disabilito fiq */
   MOV   SP, R0

#  Setup a default Stack Limit (when compiled with "-mapcs-stack-check")

   SUB   SL, SP, #USR_Stack_Size

....

executes some code and then jump to the application code.

The application code also sets stack pointer accordings to its needs during initialization.

I noticed that the User Mode stack pointer is changed properly while the IRQ stack pointer is remained the one setted by the bootloader making the system crash.

The instructions used by the application are similar to the ones used by the bootloader, the only difference is that R0 holds different value.

There is the possibility of changing the IRQ stack pointer the second time?

Thank you

[CarlosCasillas]

Hi Giovanni,

There are some considerations when developing a bootloader. For additional details, please refer to application note AN10835 “LPC2000 secondary bootloader for code update using IAP”, available on the link below:

http://www.nxp.com/documents/application_note/AN10835.pdf

Additionally, the following links may be also helpful:

https://www.lpcware.com/category/file-types/bootloader

https://www.lpcware.com/content/forum/changing-bootloader-content-through-user-applicationiap

Hope this will be useful for you.
Best regards!
/Carlos
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[giovannifriolo]

Thank you,

I solved my problem by resetting (using watchdog) bootloader and then jumping directly to application if bootloader found a magic value

in a specific location.

Best Regards

Giovanni Friolo

DAB PUMPS S.P.A.

Electronic Designer

Via Bonanno Pisano, 1

giovanni.friolo@dwtgroup.com<mailto:giovanni.friolo@dwtgroup.com>

56031 Bientina (Pisa)

+39 0587 753 840

Italy

www.dabpumps.com<http://www.dabpumps.com>;

[NilsDrotleff]

Hi

I am currently facing the same issue. How did you managed to jump directly to the user application? Have you modified the Startup file?

Thanks in advance

Nils