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IAP checksum read

Hi,

I'm using the P89LPC932A1 and attempting to read the global checksum using IAP during normal program execution. I have used this knowledgebase article as my guide:

http://www.keil.com/support/docs/2554.htm

So basically, I added this function to my code:

long unsigned IAP_ReadGlobalCRC (void)  {
  ACC = 6;                                          // MOV  A,#06H
  return ((unsigned char (code *)(void)) 0xFF03)(); // LJMP 0FF03H
}

As you can see, I changed the IAP vector from FF00 to FF03, which is what it should be. When I run the code on a real part, I do not get what I expect to get back. I generally receive back something like 0x0000000056. This is not the correct global checksum. Am I missing something? Thanks, Phil

Parents

0 Philip Garman over 19 years ago in reply to Philip Garman

Ouch. Didn't spot this. I think this knowledgebase article has a typo:

long unsigned IAP_ReadGlobalCRC (void)

should be

unsigned long IAP_ReadGlobalCRC (void)

After chaning, the code looks like it compiles correctly to:

             ; FUNCTION IAP_ReadGlobalCRC (BEGIN)
                                           ; SOURCE LINE # 80
                                           ; SOURCE LINE # 81
                                           ; SOURCE LINE # 82
0000 7406              MOV     A,#06H
                                           ; SOURCE LINE # 83
0002 12FF03            LCALL   0FF03H
                                           ; SOURCE LINE # 84
0005         ?C0007:
0005 22                RET
             ; FUNCTION IAP_ReadGlobalCRC (END)

Reply

0 Philip Garman over 19 years ago in reply to Philip Garman

Ouch. Didn't spot this. I think this knowledgebase article has a typo:

long unsigned IAP_ReadGlobalCRC (void)

should be

unsigned long IAP_ReadGlobalCRC (void)

After chaning, the code looks like it compiles correctly to:

             ; FUNCTION IAP_ReadGlobalCRC (BEGIN)
                                           ; SOURCE LINE # 80
                                           ; SOURCE LINE # 81
                                           ; SOURCE LINE # 82
0000 7406              MOV     A,#06H
                                           ; SOURCE LINE # 83
0002 12FF03            LCALL   0FF03H
                                           ; SOURCE LINE # 84
0005         ?C0007:
0005 22                RET
             ; FUNCTION IAP_ReadGlobalCRC (END)

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