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From: goss on 5 Oct 2006 16:58
Hi everybody,

I'm going to build a USB JTAG cable and I don't know what protocol
should I use for communication. The only cable I can fully implement
this time is the Digilent USB cable... (according to the code of Zoltan
Csizmadia's cable server project)
I was trying to reverse engineer Xilinx's USB Platform cable protocol,
but after a point I gave up. (Mostly becouse the firmware of the cable
is shipped with the PC software, so they can easily modify the protocol
in the new version of ISE)

So, some questions:
Is Digilent's protocol free to implement in my device?

Is there any cable with open protocol? (with a GPL like license)
If exists an open protocol cable, is this well supported by
applications?

Thanks,
goss

From: Amontec, Larry on 6 Oct 2006 03:28
goss wrote:
> Hi everybody,
>
> I'm going to build a USB JTAG cable and I don't know what protocol
> should I use for communication. The only cable I can fully implement
> this time is the Digilent USB cable... (according to the code of Zoltan
> Csizmadia's cable server project)
> I was trying to reverse engineer Xilinx's USB Platform cable protocol,
> but after a point I gave up. (Mostly becouse the firmware of the cable
> is shipped with the PC software, so they can easily modify the protocol
> in the new version of ISE)
>
> So, some questions:
> Is Digilent's protocol free to implement in my device?
>
> Is there any cable with open protocol? (with a GPL like license)
> If exists an open protocol cable, is this well supported by
> applications?
>
> Thanks,
> goss
>
Checkout JTAGkey and JTAGkey-Tiny from http://www.amontec.com .
Amontec will provide the jtagkey.dll very soon!
But you can still use the OpenOCD JTAG server, and it is GPL and fully
supporting the JTAGkey products.
Note the JTAGkey products are based on FTDI FT2232!


Best regards,
LOL
From: zcsizmadia@gmail.com on 6 Oct 2006 12:04
I've implemented the whole Digilent USB protocol and already working in
cblsrv-0.2 (with Impact). When I have some time, I will upload the
latest version to sourceforge.net.

Zoltan

goss wrote:
> Hi everybody,
>
> I'm going to build a USB JTAG cable and I don't know what protocol
> should I use for communication. The only cable I can fully implement
> this time is the Digilent USB cable... (according to the code of Zoltan
> Csizmadia's cable server project)
> I was trying to reverse engineer Xilinx's USB Platform cable protocol,
> but after a point I gave up. (Mostly becouse the firmware of the cable
> is shipped with the PC software, so they can easily modify the protocol
> in the new version of ISE)
>
> So, some questions:
> Is Digilent's protocol free to implement in my device?
>
> Is there any cable with open protocol? (with a GPL like license)
> If exists an open protocol cable, is this well supported by
> applications?
>
> Thanks,
> goss

From: zcsizmadia@gmail.com on 6 Oct 2006 12:12
Sorry, I misunderstood the question :)

If you want to use it from cblsrv (using Impact), I 'd make the
protocol very similar to the cblsrv protocol. One of the problem with
Digilent protocol is it is not very efficient when you are doing a lot
of short Shift-IR, Shift-DR operations. That is why reading or writing
a platform flash is much slower with Digilent-USB than with Parallell
III cable. Of course you should implement the very raw access to JTAG
pins as well, but for performance reasons I 'd create some higher level
command. (eg. cblsrv WRITE)

Zoltan

From: Eric Smith on 6 Oct 2006 21:24
"Amontec, Larry" <laurent.gauch(a)ANTI-SPAMamontec.com> writes:
> Checkout JTAGkey and JTAGkey-Tiny from http://www.amontec.com .

Looks very nice! And the pricing on JTAGkey-Tiny is certainly very
attractive.

Aside from lower price and not having a molded plastic case, are there
any other differences between JTAGkey and JTAGkey-Tiny?

Thanks,
Eric
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