Reading a Micro

Discussion in 'Embedded Systems and Microcontrollers' started by spreston36, May 28, 2008.

  1. spreston36

    Thread Starter New Member

    May 28, 2008
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    Hey,

    I have a micro that I need to get the dat aoff of, there is no security that needs bypassing.

    I have used a standard reader and the binary is coming out wrong (the reset vector is not valid for the memory map that the micro has)

    is there another way I can get data off the chip? or is there some easy fix for the reset vector coming out wrong?

    thanks!
     
    Last edited: May 28, 2008
  2. Papabravo

    Expert

    Feb 24, 2006
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    Which micro are we talking about and how are you reading it?
     
  3. spreston36

    Thread Starter New Member

    May 28, 2008
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    hey, i'm ust using a general purpose reader.

    I'm abl eto read in binary that is in the correct memory rom range however the reset vector is reading in as something that is out of range of the rom.

    so my real question i guess is what would cause the reset vector to be wrong? is it my reading method?

    I'm reading in as binary and as .s19 and both have the same issue
     
  4. Papabravo

    Expert

    Feb 24, 2006
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    General purpose reader is not a helpful description. The use of .s19 files and RESET vector suggests that you are using a Freescale(formerly Motorola) processor. There could be several explanations for the behavior that you are observing. One possible explanation is that depending on how things are "mapped" the content of the RESET Vector may have one or more "don't care" bits. It would help to have a schematic of the board that the processor is intended to be mounted to.
     
  5. hgmjr

    Moderator

    Jan 28, 2005
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    Is the microprocessor a 16-bit micro? If so you may be looking at a "big endian" versus "little endian" problem.

    In some 16-bit microcontrollers the low-order byte comes first and in others the high-order byte comes first. You may be looking a manifestation of a byte-swap.

    hgmjr
     
  6. spreston36

    Thread Starter New Member

    May 28, 2008
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    the reader is a data i/o reader

    I'm debugging the chip and my overall goal is just to get the data off of it so i dont have a board that it could go to.

    the dont cares is one thing i didnt consider, is there a way I can tell if the reset vector has dont cares in it?

    Also I did consider the endian and sadly even if its bit flipped its still out of range for a valid reset.
     
  7. RiJoRI

    Well-Known Member

    Aug 15, 2007
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    If this was not a typo, then there is a problem in your understanding of endedness. It is the bytes that are reversed, not the bits. So an address $1234 for a little-endian chip would be $3412, and for a big-endian chip, $1234. In no case would it go from $1234 to $2C48 (0001 0010 0011 0100b to 0010 1100 0100 1000b).

    --Rich
     
  8. Papabravo

    Expert

    Feb 24, 2006
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    Just tell us what the processor is and give us the lines from the S19 file that contain the RESET vectors, and all will be explained to you (maybe?). The schematic is important because Motorola processors may come out of RESET in one of four modes depending on the strapping of the MODA, MODB pins. The actual RESET vector may be in external memory rather than internal memory and so forth.
     
  9. spreston36

    Thread Starter New Member

    May 28, 2008
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    rich - fortunately it was a typo but thank you for taking to time to help out :)

    papabravo- sadly its business sensitive so I'm not at liberty to give any more information that I have. which makes my job that much harder :p
     
  10. hgmjr

    Moderator

    Jan 28, 2005
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    That significantly ties our hands. Sadly, you're on your own with this one.

    hgmjr
     
  11. Papabravo

    Expert

    Feb 24, 2006
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    Yeah, boy them interrupt vectors contain a boatload of useful information that I'm just dying to purloin.
     
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