[NBLUG/talk] JTAG hacking

Sat Apr 14 14:18:13 PDT 2012

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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