Lpc2000

I am wondering how this works when debugging a product through the 
2nd JTAG.  It seems like you could never run the code that is 
already in the part as you would have to erase it and download the 
bit of code to enable the 2nd JTAG.  Correct?

Rich





 --- In lpc2000@yahoogroups.com, "ian48harry" <ahi93@d...> wrote:
> 
> Marcus:
> 
> Comments next to your questions.
> 
> Regards,
> 
> Ian
> 
> --- In lpc2000@yahoogroups.com, Markus Meng 
<meng.engineering@b...> 
> wrote:
> > Hi Richard,
> > 
> > 
> > 
> > - concerning 2nd JTAG I wonder if I can use the very same
> > JTAG ARM Adapter 2x10 Pin to connect to the 2ndary JTAG?
> Ian > Yes, exactly the same.
> 
> > 
> > - If so, I can make a board without the primary JTAG and
> > it is still possible to debug code? Is this correct.
> Ian > Yes, with the caveat to question three.
> 
> > 
> > - I do not understand the disadvantages, if I make use of
> > the 2nd JTAG only. It uses less pins than the primary, and
> > I always need SW to enable it. Is this correct?
> Ian > The secondary JTAG is enabled by software so you cannot get 
> there unless you have the part FLASHed with the right code.  You 
> cannot load a RAM based example unless the JTAG is enabled first 
> which means the right part of code MUST be in FLASH first.  You 
can 
> of course load a small application to enable the secondary JTAG 
via 
> the serial port.
> 
> > 
> > Best Regards
> > Markus Meng
> > 
> > Richard schrieb:
> > 
> > >I am planning to use the secondary JTAG (LPC2104) in a design.  
I 
> > >have already been debugging (from flash) using the second JTAG 
by 
> > >placing a firmware in flash to enable the second JTAG pins and 
> then 
> > >starting the debugger.
> > >So, in the actual application, I will have to load the JTAG 
enable 
> > >firmware everytime(via ISP)I want to debug or program via the 
2nd 
> > >JTAG port, correct?
> > >I have dip switches in the design, could I use one of these to 
> > >trigger software to write to PINSEL1 and enable the 2nd JTAG?
> > >
> > >Thanks
> > >
> > >Rich
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > 
> > >Yahoo! Groups Links
> > >
> > >
> > >
> > > 
> > >
> > >
> > >
> > >
> > >  
> > >
> > 
> > -- 
> > Mit freundlichen Grüssen
> > Markus Meng
> > 
> > 
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