Lpc2000

Dominic Rath wrote:

>My project has been designed from ground up to be able to support different 
>JTAG interfaces. Currently, it supports Wigglers, the FTDI FT2232C and a new 
>configuration for the Amontec Chameleon Dongle (not yet released, but works 
>really fine - ARM7TDMI RAM download at 60-70kByte/s). I've never used a real 
>wiggler or a homemade one, so I don't know about the problems with these, but 
>the Amontec Chameleon works just fine. It has a true IEEE1284 transceiver on 
>the PC side (guess that guarantees good signal integrity over a long cable 
>length) and a Xilinx CoolRunner CPLD (3.3/5V tolerant IO), and I've never had 
>any problems with signal integrity at up to 16 MHz JTAG clock (that's for the 
>new config, Wiggler wont go beyond 500kHz).
>
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Thank you for that information, that may be useful to pass along to my 
customer as they may wish to do something with JTAG.

>The software part is mostly independent from the underlying JTAG interface - 
>all the tricky logic can be implemented equally well for a wiggler and a much 
>smarter (and more expensive) device. This would give users the freedom to 
>choose between hobbyist quality at a few $, or some more money for a 
>thoroughly designed interface offering high TCK and a failure-proof 
>electrical interface - both offering the same functionality.
>
>Personally, I'd favor a FPGA based solution, using USB 2.0. Such a setup would 
>allow very high speed at low cost while still offering more flexibility than 
>a uC based solution with an Ethernet interface.
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Well, the only concern would be portability.  From what I find with USB 
is that it can be very operating system centric.  I would, and have, 
favored ethernet because it is platform agnostic.  I tire of having to 
look at USB compatibility lists when considering to purchase that latest 
USB goodie.  So many of them are built with very little attention to 
running on anything other than Windows.  You can hide a lot of 
non-standard behavior, or make up for a complete disregard for 
standards, in a driver.  e.g. "when all else fails, make a driver for it".

Regards,

TomW


>Regards,
>
>Dominic Rath
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>Yahoo! Groups Links
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-- 
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net, http://cyberiansoftware.com
"Windows? No thanks, I have work to do..."
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