[NBLUG/talk] JTAG hacking
Robert P. Thille
list-nblug-talk at rangat.org
Fri Apr 27 17:02:18 PDT 2012
I don't think JTAG adapters are very expensive these days. I went to Design West (free expo pass), and picked up a free LPCXpresso board that can act as a JTAG adapter, but I'm unsure how compatible it is with general JTAG driving software. ( http://ics.nxp.com/lpcxpresso/#Products look for LPC-Link ). Looks like Digikey has the dev-board for $29.95: http://search.digikey.com/us/en/products/EA-XPR-003/EA-XPR-003-ND/2410099 and others slightly cheaper: http://search.digikey.com/us/en/cat/programmers-development-systems/general-embedded-dev-boards-and-kits-mcu-dsp-fpga-cpld/2621773?k=lpcxpresso
I've also got a 'JTAGKey-tiny' ( http://www.amontec.com/jtagkey-tiny.shtml ) and a 'JTAGKey' ( http://www.amontec.com/jtagkey.shtml ) [if the tiny won't work] around here somewhere that you could probably borrow.
I think they are primarily for ARM boards, but I don't see why they wouldn't work with another board if the pinout is the same, or if you wired up an adapter.
Robert
On Apr 14, 2012, at 2:18 PM, akleider at sonic.net wrote:
>
> I believe ftdi is the driver needed for jtag and I believe it comes with
> the default instal of Debian. I've used jtag (without knowing much about
> it and understanding even less) with regard to the Marvell 'plug' devices:
> SheevaPlug and DreamPlug. You've already been sent a link to the jtag
> interface that they sell. (It's built in to the Sheevaplug but you need
> the one they sell to use jtag on the DreamPlug.
>
>> Hello,
>>
>> I'll have to track down a computer with a parallel port.
>>
>> However, I would really prefer to have a serial JTAG connector - a USB
>> one would be *amazing*. Most of the ones I've found are from shady xbox
>> hacking sites. Most of the tutorials and software used are
>> Windows-specific; anyone know where I can find a decent (preferably
>> cheap) JTAG connector? Anyone know of any JTAG software for Linux?
>>
>> I appreciate all the help, people!
>>
>> On 04/14/2012 08:19 AM, Mitch Patenaude wrote:
>>> I haven't done any JTAG hacking myself, but If I recall correctly, that
>>> DB25 cable you're talking about is parallel, not serial, so a DB9 serial
>>> converter won't help you. I also recall that hardware hackers say that
>>> having a parallel port on the motherboard is invaluable, since the
>>> USB<->Parallel converters don't work in this situation. If you don't
>>> have a parallel port, just invest in the more expensive USB JTAG device
>>> (or borrow, if you're just going to use it once.)
>>>
>>> -- Mitch
>>>
>>> On Fri, Apr 13, 2012 at 10:43 PM, Glenn Kerbein
>>> <glenn at spontaneousdancing.net <mailto:glenn at spontaneousdancing.net>>
>>> wrote:
>>>
>>> Hello,
>>>
>>> Let me clarify. I did some more googling around. Apparently the JTAG
>>> connector turns into a DB25 serial cable. Further discussion with
>>> the engineer tells me that it is not "genuine" serial communication.
>>> I was hoping to find a DB25-DB9 converter (I'll scrounge for one,
>>> there's gotta be one somewhere). From the DB9, I'll feed that into a
>>> USB-to-Serial converter.
>>>
>>> Hopefully I'll be able to use some JTAG-compatible program.
>>>
>>> Then, SCIENCE!?
>>>
>>> Still kinda at a loss here, and I'd appreciate any help in getting
>>> the right connectors and software.
>>>
>>> Optimally, I wouldn't need to install additional software on there.
>>>
>>> Best,
>>> Glenn
>>>
>>>
>>> On 04/13/2012 09:16 PM, Mark Street wrote:
>>>
>>> Hmmm,
>>>
>>> I am trying to picture that in my mind.. a huge serial cable.
>>> which
>>> piece do you need?... I have a JTAG unit that I use with my
>>> Globalscale
>>> Dreamplug devices, on which I run Debian Wheezy.
>>>
>>> USB off one end of the JTAG box to the computer and off the
>>> other end
>>> two small custom cables for the JTAG interface and UART
>>> interface of the
>>> tiny mobo. My Globalscale devices use UBoot.
>>>
>>> http://www.__globalscaletechnologies.com/p-__28-guruplug-jtag.aspx
>>> <http://www.globalscaletechnologies.com/p-28-guruplug-jtag.aspx>
>>>
>>>
>>>
>>> On 4/11/2012 6:45 PM, Glenn Kerbein wrote:
>>>
>>> Good day NBLUG,
>>>
>>> I need some assistance with assessing the hardware on an
>>> embedded device.
>>>
>>> I have an motherboard that normally runs Linux (a variant of
>>> Debian,
>>> but I can't be sure). If they operate normally, you can
>>> modify the
>>> BIOS by flashing the SPI (whatever that is). If the device
>>> is broken
>>> beyond repair, and the BIOS is to blame, then a new BIOS can
>>> be
>>> flashed onto the board using a JTAG connector. I have one
>>> half of the
>>> JTAG connector - I just need to figure out how to get the
>>> BIOS image
>>> to talk over a huge serial cable.
>>> The issue is that I don't have all the JTAG cabling, etc. to
>>> make this
>>> work. I'm waiting on someone else to provide it to me.
>>>
>>> I was Googling around at JTAG. Most people use these
>>> connectors to
>>> hack their xboxes. One person figured out how to bridge the
>>> serial
>>> JTAG to a serial to female USB port.
>>>
>>> I know someone on this list posted that they have a bunch of
>>> xboxes.
>>> Do you have any JTAG connectors for said xboxes?
>>>
>>> I appreciate any input you have!
>>>
>>> Best,
>>> Glenn
>>>
>>>
>>>
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>>
>> --
>> Living well is the best revenge
>>
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