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LPCXpresso LPC1769 - is it possible to put own firmware to theLPC3154 in the LPC-Link part?

Discussion in 'Embedded' started by wzab, May 20, 2011.

  1. wzab

    wzab Guest

    I've just started to work with LPCXpresso LPC1769. Unfortunately it
    seems, that the LPC-Link is able to work only with the CodeRed
    software and doesn't work with OpenOCD.
    As full schematic of LPC-Link part is available (
    http://www.embeddedartists.com/products/lpcxpresso/LPCXpressoLPC1769revB.pdf
    ), it should be possible to write and put my own firmware to the
    LPC-Link part (BTW it is nice piece of hardware which could be used to
    make quite flexible open JTAG dongle ;-) ).

    Is it possible to replace the original firmware in LPC3154 with my
    own, or is it somehow locked by the OTP in LPC3154?
    Has anybody tried to do it?
     
    wzab, May 20, 2011
    #1
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  2. wzab

    Arlet Ottens Guest

    An interesting idea, but doesn't appear to be possible:

    http://electronics.stackexchange.com/questions/11275/reprogramming-lpc3154-at-lpcxpresso
     
    Arlet Ottens, May 21, 2011
    #2
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  3. wzab

    wzab Guest

    I'm afraid you are right... Quick inspection of the board and its
    schematic layout
    leads to assumption that the JTAG pins are available (9 undocumented
    pads on the lower
    edge of the LPC-Link board are probably connectors to the "breakout
    section LPC3154-JTAG",
    however the order of pins is probably changed, as most left is GND and
    most right is
    Vcc).
    The question is however if the JTAG is still left enabled... Probably
    not.

    So it seems, that the most effective solution to work with the target
    part
    of LPCXpresso LPC1769 is simply to remove the LPC-Link part and attach
    any other
    not vendor-locked JTAG dongle... (e.g. http://code.google.com/p/opendous-jtag/
    ).
     
    wzab, May 21, 2011
    #3
  4. wzab

    Rich Webb Guest

    Rowley tried to go in through the front door to get an official sanction
    from NXP to use that interface. No joy. See
    <http://rowley.zendesk.com/entries/163115-lpcxpresso-lpc-link>

    I suppose that if one had enough tools and enough time then reverse
    engineering the protocol would be possible. However, given the large
    number of existing JTAG options, including some that are quite
    inexpensive, doing so would only be for the benefit of getting "hacker
    cred" for the effort.
     
    Rich Webb, May 21, 2011
    #4
  5. wzab

    wzab Guest

    If I were a developer of this solution I'd provide full encryption in
    the USB layer also.
    LPC1354 is powerful enough to handle encrypted data stream.
    So probably even analysis of the USB protocol will not give any
    results.

    The only way would be to find the 128-bit AES key and encrypt own
    firmware with it.
    Quite interesting if the method used to transfer the firmware is
    resistant to
    plaintext cryptoanalysis, as probably the header of the firmware is
    quite predictable ;-).
    OK. I have no time to go further with that...

    Well, I've simply cut off the LPC-Link, soldering a male gold-pin
    connector
    to the target board and a female gold-pin connector to the LPC-Link.
    So I can still quickly connect the LPC-Link if one of my students is
    going to use
    the closed Code Red solution, while another open JTAG controller may
    be connected
    for everyday use with OpenOCD.
     
    wzab, May 21, 2011
    #5
  6. wzab

    Arlet Ottens Guest


    It's funny that the LPC3154 on the board is much more powerful than the
    LPC1769, and it's only being used as a JTAG interface.

    I'd love to have a freely accessible LPC3154-only board for the price of
    the LPCexpresso.
     
    Arlet Ottens, May 21, 2011
    #6
  7. wzab

    wzab Guest

    And that's probably why it is sold in such "closed" state...
    From NXP point of view it is a way to promote LPC1769 without
    disturbing market for LPC3154 ;-).
    The LPC3152 (like 3154 but without AES protection) kit
    costs 179€ http://www.embeddedartists.com/products/kits/lpc3152_kit.php
    (well, it is a little better equipped than LPCXpresso target board)
     
    wzab, May 21, 2011
    #7
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