Lpc2000

> > You can't get anywhere near that on ARM7TDMI-S parts which we are 
> > dicussing,
 
Correct.  The maximum speed I can use with the JTAGjet is 4MHz on these LPC parts.
BTW, I was incorrect before, the JTAGjet goes to 30MHz when I checked it again.

>> said in this instance we've proven that the expensive JTAGjet is slower
>> than a $20 wiggler when downloading and flashing an LPC229x.  I've even
>> provided numbers to prove it.

It is not as simple as you try to make it.  The Signum Chameleon debugger software has a ton of features, and many different options and capabilities.  The price is not so much for the debugger hardware, as it is for the software.  The software is superb.  Best debugger I have ever used by far.  Price I paid was $1200, and when you compare that to Greenhills and others I think it is a good value and much cheaper.  It also supports a ton of CPUs and DSPs.

Programming can be done in different ways, and each has different advantages and disadvantages.  One method may take longer than another, but the way in which Signum handles this provides great flexibility and control.

>> Try this link.  http://www.arm.com/support/faqip/3732.html.  Extracting
>> the relevent details, "If the RTCK output is not used, it is required
>> that TCK is running at a maximum of 1/6th the system clock frequency if
>> only 1 JTAG synchroniser is implemented in the system."  

I use both the Adaptive clocking (RTCK) and fixed freq on my JTAGjet.  It does both equally well.

>> For example using proper speed cabling 
>> and including simple RC filters to reduce signal crossover at 
>> high speeds near part pins.
> No, you're completely wrong here.  The factors are part of the JTAG
> design on the part, as the above link shows.

Correct.  I have actually tried attaching caps on the JTAG header pins and nothing I did made any difference on the 4MHz speed limitation.

> > USB 2.0 conformance does not imply a high speed device.  CrossConnect is
> > a USB 2.0 full speed device. Is the JTAGjet a full speed or high speed device?  

It is Full speed.  The USB-2 terminology has become misused, and if you look at the USB.ORG web site you will see a notice that they actually do not want people saying "USB 2.0" if it is only full speed.  Philips makes this same exageration on their own 2148 series parts which say "USB 2.0" but they are Full speed.

>> What does "examining a breakpoint" mean?  
>> How much data do you need to upload at a breakpoint for heaven's sake?

A ton.  I have watches on large structures where I need to read 8K blocks of data, and that data must be read whenever I stop the CPU.  There is a lot of data flow, but then Chameleon processes a lot of data.  In some cases I also need to download corrected blocks to RAM.  It's just a whole lot snappier with the JTAGjet than a wiggler.  At least that's what I see.

Chris.



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