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Watchdog

When a watchdog timeout occurs, it could be the result of many causes. The code could be 'out in space' due to a bad pointer corrupting anything it wants to. It could be due to a fault condition that did not affect data space. Who knows?

Since the watchdog reset is considered a 'hard reset' we know where it will then start execution from.

If I want to save existing data ram into flash prior to executing __main() I would think the place to do this would be here:

; Reset Handler
Reset_Handler   PROC
                EXPORT  Reset_Handler             [WEAK]
                IMPORT  __main
                LDR     R0, =__main
                BX      R0
                ENDP

I could jump into a routine which calls an IAP command to save RAM to flash and then return to finish the startup.

I would have to EXPORT the routine I want to jump to as well as load the LR with the return value. Is there anything else that I am missing?

BTW: the processor is a Cortex M3 core.

Thanks.

Parents

0 grz bzz over 15 years ago in reply to Tamir Michael

My bad.

Same .asm code is used for both. Did open my damn eyes enough.

__asm void SVC_Handler(void)
{
        IMPORT SVC_Handler_C
        TST lr, #4
        MRSEQ r0, MSP
        MRSNE r0, PSP
        B SVC_Handler_C
}

__asm void HardFault_Handler(void)
{
        IMPORT HardFault_Handler_C
        TST LR, #4
        MRSEQ R0, MSP
        MRSNE R0, PSP
        B HardFault_Handler_C
}

FYI: The above code seems to work fine - so far.

Reply

0 grz bzz over 15 years ago in reply to Tamir Michael

My bad.

Same .asm code is used for both. Did open my damn eyes enough.

__asm void SVC_Handler(void)
{
        IMPORT SVC_Handler_C
        TST lr, #4
        MRSEQ r0, MSP
        MRSNE r0, PSP
        B SVC_Handler_C
}

__asm void HardFault_Handler(void)
{
        IMPORT HardFault_Handler_C
        TST LR, #4
        MRSEQ R0, MSP
        MRSNE R0, PSP
        B HardFault_Handler_C
}

FYI: The above code seems to work fine - so far.

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