Is it possible to have primary jtag interface enabled with acess to other i/o ports including the ports shared with ETM. In user manual there is a table that describe DBGSEL enable JTAG as well as ETM so I suppose all pins used by ETM are inaccessible for application use. Is it correct? Should I use in this case only secondary JTAG with software enable? I need to have only JTAG pins enabled and use all other pins. |
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ETM disabled with primary JTAG enabled on LPC2109.
Started by ●October 3, 2004
Reply by ●October 4, 20042004-10-04
Unfortunately you get all or nothing with the DBGSEL/RTCK. The ETM is enabled along with the primary JTAG signals when DBGSEL and RTCK are asserted on reset (as stated in the user manual). A total of 15 pins are taken away from IO as a result of this scenario. Using the secondary JTAG signals (switched on via the pinsel1 register, irrelevant of DBGSEL/RTCK) allows you to debug via JTAG and only take up 5 IO pins. You don't get the ETM, yet you save 10 IO pins. This is the scenario I am using for debugging, and it works marvelous. However, there is one gotcha. If your firmware takes a reset you will lose JTAG control over your processor until pinsel1 gets set back to the correct state to enable the secondary JTAG pins. This can be bad if you are trying to debug a firmware problem that happens early in your restart sequence. My solution to this scenario (so far) is to put a for() loop waiting for a volatile 32 bit memory location (initially set to 0) to change to non-zero, right after the secondary JTAG pins are enabled, which is done early in the restart sequence. This way I simply start up the debugger (Insight with mpDemon in my case) and stop the processor (which is waiting in the for() loop), set the 32 bit value to non-zero then set my hardware breakpoint(s) (I am running from Flash) and let the processor continue. - Rod -- ___ ____ ___ _ ___ Rod Moffitt / _ \/ __ \/ _ \ (_)__ / _/__ http://rod.info / , _/ /_/ / // / / / _ \/ _/ _ \ /_/|_|\____/____(*)_/_//_/_/ \___/ ======================================================= ~ Where loved ones are remembered http://memoriam.org ~ On Sun, 3 Oct 2004, radoslaw_mitura wrote: > > > Is it possible to have primary jtag interface enabled with acess to > other i/o ports including the ports shared with ETM. > In user manual there is a table that describe DBGSEL enable JTAG as > well as ETM so I suppose all pins used by ETM are inaccessible for > application use. Is it correct? > Should I use in this case only secondary JTAG with software enable? > I need to have only JTAG pins enabled and use all other pins. > > > Yahoo! Groups Links |
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Reply by ●October 5, 20042004-10-05
Hi, I guess you are talking about the LPC2106 (there is a LPC2119) so I don't really know which one you are referring to. The LPC2106 offers the option to enable all debug channels, primary JTAG AND ETM or the secondary JTAG (Application Note see in the "Files" section of this user group) The LPC2119 (or LPC2114) offer less RAM but more I/O and the option to enable JTAG OR ETM or both. Cheers, Bob --- In , "radoslaw_mitura" <radoslaw_mitura@y...> wrote: > > Is it possible to have primary jtag interface enabled with acess to > other i/o ports including the ports shared with ETM. > In user manual there is a table that describe DBGSEL enable JTAG as > well as ETM so I suppose all pins used by ETM are inaccessible for > application use. Is it correct? > Should I use in this case only secondary JTAG with software enable? > I need to have only JTAG pins enabled and use all other pins. |
Reply by ●October 5, 20042004-10-05
I hate to reply to my own post - yet I just want to make it clear that my note applies to the LPC2104/2105/2106, and not to some of the other LPC2K family members which have separate JTAG/ETM control (like the LPC2114/2124/2212/2214 and LPC2119/2129/2194/2292/2294). Where is this mysterious LPC2109 part anyway? ;) |
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Reply by ●October 6, 20042004-10-06
Sorry. I meant 2106. --- R M <> wrote: > > I hate to reply to my own post - yet I just want to > make it clear that > my note applies to the LPC2104/2105/2106, and not to > some of the other > LPC2K family members which have separate JTAG/ETM > control (like the > LPC2114/2124/2212/2214 and > LPC2119/2129/2194/2292/2294). Where is this > mysterious LPC2109 part anyway? ;) > > _______________________________ |