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???
09/22/06 11:56
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 		 #124858 - boot vector lost
Responding to: ???'s previous message
Vigneshwara Baliga said:
When you say Boot Vector is blown, Do I presume that the “Boot Vector” register no longer has value 0xFC, but may contain some garbage value?

Most probably it contains 0x00.

One of the reasons for the "bootvector loss syndrome" is impaciency.

It takes several seconds (according ro datasheet, 11s) to perform a full chip erase. That's a lot, and FM does nothing visible during this time; and the impatient ones tend to pull the cord... During full chip erase, the bootvector (and statusbyte, too) gets erased; now funnily these two bytes erase to 0x00 contrary to the rest of FLASH, which erases to 0xFF. The internal algorithm of the bootloader restores the default value of bootvector (into 0xFC) AFTER the full chip erase is finished; but if you pull the cord before it...

JW



List of 49 messages in thread
TopicAuthorDate
Need Help: Problem with ISP on P89C51RC2HBA            01/01/70 00:00      
   application?            01/01/70 00:00      
      only if he misspelled            01/01/70 00:00      
         my bad            01/01/70 00:00      
            Still            01/01/70 00:00      
      application?            01/01/70 00:00      
         FIRST, second and third            01/01/70 00:00      
         I'm afraid...            01/01/70 00:00      
            It's in the errata            01/01/70 00:00      
               it's a stupid practice...            01/01/70 00:00      
                  not from their perspective            01/01/70 00:00      
                     we discussed this already many times            01/01/70 00:00      
                     Why not make them OTP's, then?            01/01/70 00:00      
                        they are if you follow the instructions            01/01/70 00:00      
                           compromise            01/01/70 00:00      
                              just exactly HOW do you "push" on the mfg?            01/01/70 00:00      
                                 push on the mfg            01/01/70 00:00      
                                    only works when you spend MONEY            01/01/70 00:00      
                     An Old chip will known Devil ?            01/01/70 00:00      
               bootvector lost already            01/01/70 00:00      
                  there IS code in the chip            01/01/70 00:00      
                     how do you mean?            01/01/70 00:00      
                        Rx+            01/01/70 00:00      
               I found an errata            01/01/70 00:00      
            I'm afraid...            01/01/70 00:00      
               drop me an e-mail via my profile            01/01/70 00:00      
            I'm afraid...            01/01/70 00:00      
   first, second third            01/01/70 00:00      
      Must be an Atmel's micro...            01/01/70 00:00      
         naah, that is NOT the issue            01/01/70 00:00      
      first, second third            01/01/70 00:00      
      first, second third: second            01/01/70 00:00      
         boot vector lost            01/01/70 00:00      
   Try this            01/01/70 00:00      
      Try this            01/01/70 00:00      
         FM            01/01/70 00:00      
            FM            01/01/70 00:00      
               FM can not restore a lost bootvector            01/01/70 00:00      
               it's too late            01/01/70 00:00      
                  it's too late            01/01/70 00:00      
                     do not            01/01/70 00:00      
                        Oh...            01/01/70 00:00      
                           no chip 'requires' reset IC but ALL flash based ..            01/01/70 00:00      
                           the trouble with RC resets...            01/01/70 00:00      
                              How, exactly, did you arrive at this notion?            01/01/70 00:00      
                                 experience...            01/01/70 00:00      
                                 the reason            01/01/70 00:00      
                        Go for the "V"!            01/01/70 00:00      
                           while these are valid concerns            01/01/70 00:00      

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