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LPC2106 JTAG Programming Confusion!!

Discussion in 'Embedded' started by amerdsp, Aug 26, 2007.

  1. amerdsp

    amerdsp Guest

    I am reading mixed information about the ability to program the 2106
    using a parallel port wiggler. Some say that it is only possible to
    program the device via RS232 but others say that it is possible to do
    the JTAG programming.

    What am I missing? What do I need to have to be able to use JTAG for
    programming the chip if possible?

    Thank you,

    -- A
    amerdsp, Aug 26, 2007
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  2. amerdsp

    Stephane Guest


    You can program you LPC through JTAG. NXP embedds a bootloader in its
    LPC devices.This bootloader allows you to program the device via
    RS232, but it also exports its routines for onchip use (and
    unfortunately, this is the only way to write flash from onchip OS, as
    NXP doesn't document the interface for the internal flash controller).

    So, in order to program your device using JTAG, you have to write a
    piece of code that you will push into the chip RAM (using JTAG). You
    piece of code will call the NXP bootloader flash routine, and will be
    able to communicate with you PC-hosted programmer over JTAG (for ex,
    push data in RAM buffer, push arguments in registers, push program
    routine address in PC, run).

    This is not the funny part and you are walking in the dark when you do
    something like this. Therefore, for 70€ I would rather direct you to
    http://www.isystem.com. They sell a nice starter dev kit including a
    rather complete IDE, a USB JTAG wriggler and a LPC2138 header board. I
    have just bought one and I definitely don't regret my money. I just
    checked, LPC2106 is supported.
    Even if you don't want to buy their kit, you can have a look at their
    free demo, they might include source for the chip side downloader
    (though it will be design for their own PC side downloader).

    By the way, if anyone has information about LPCs flash controller
    registers, I am definitely interested. I am currently trying to
    reverse their bootloader to extract this information, but this is
    about 12k binary dump to inspect... I don't want to rely on "third
    party" software for my low level code


    Stephane, Aug 26, 2007
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