Lpc2000

bruce_p1 wrote:

>Tom,
>
>What you describe is the norm for secondary JTAG debugging and is 
>well understood.  But, some people, including myself, have seen this 
>not work on some LPC chips on certain circuit boards.  The only way 
>I saw it fixed was to keep DBGSEL high and RTCK low.
>
>I have designed quite a few other boards that work perfectly, but 
>have now seen random chips not allowing a secondary JTAG 
>connection.  This makes me wonder if there is a certain combination 
>of things that cause this issue (e.g., on-board capacitance, certain 
>batches of chips from a certain fab, reset timing, crystal 
>frequency, power supply sequencing, timing issue with DBGSEL, 
>etc.).  These things can probably only be answered by the Philips 
>designers is my guess.
>
>  
>
Perhaps telephone the local Philips Field Rep and get on their case 
about the issue?

Regards,

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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