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Re: [lpc2000] Daisy chain JTAGs

2006-03-30 by Tom Walsh

clemens fischer wrote:

>>Tom Walsh:
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>>Has anyone experienced this?  Is the wiring of multiple JTAG ports as
>>I described?  Do I, or should I, consider using the RTCK signal?
>>    
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>isn't the RTCK signal *required* on ARM7TDMI-S cores?
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No.  Only if you run adaptive clocking do you need the RTCK signal.  
But, if you run at a fixed clocking rate you don't need it.  I do think 
that this may be something I should consider, using adaptive clocking?

My problem is that I have the TCK set to the slowest possible setting 
and I have occassional problems synchronizing.  When the problem occurs, 
it can take 10 or more attempts to synchronize, usually 2..4 attempts.  
Something else I need to try, again, is terminating the signals at the 
far end of the chain.

I finally did get an email reply from Ultimate Solutions (U.S. 
distributor for Abatron) about the daisy chain wiring.  The wiring is 
correct: all signals are parallel with the exception of the obvious, TDI 
+ TDO signals.  I can appreciate that since I didn't spend $4K for thier 
ARM development package, or spend $800 for the telephone support.  They 
seem to be slow at paying attention to email support. :(

A nice product, but the support is not what I expected for the price.

TomW

-- 
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net, http://cyberiansoftware.com
"Windows? No thanks, I have work to do..."
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