Lpc2000

On Thursday 09 March 2006 01:29, Robert Wood wrote:
>  >> >JTAG and debug are NOT the same. For those who are educated the
>  >>
>  >> meaning of the word debug is made clear by the context. In the
>  >> context of CRP, debug clearly means enabling the debug bus signal to
>  >> act, which JTAG, if enabled, may be attempting to assert. Lack of
>  >> real educated insight is giving rise to confusion that should not
>  >> exist and I should not be expected to clarify, particularly to those
>  >> who claim or imply expertise. Clearly debug can also mean JTAG, but
>  >> in a different context.
>
> As far as Philips LPC2xxx chips are concerned, debug and JTAG _are_ the
> same.
> There's no boundary scan implemented on the LPCs, only the debug scan
> chains
> that are part of the ARM7TDMI-S core. When CRP is enabled, JTAG/Debug
> doesn't
> work. <<
>
> Actually, for once, I can see John's reasoning. The way I understand it.
> the JTAG is just the interface, which happens to carry the signals from
> the debug unit. It could be called the Philanium Doggle Whack interface
> and have a 1,000 bit wide interface, but still be carrying the same
> debug information. It's possibly like calling TCP/IP Ethernet. Just
> because Ethernet normally carries TCP/IP doesn't mean it always is.

Yeah, but I don't think that's what he means, when he insists on telling that 
"In the context of CRP, debug clearly means enabling the debug bus signal to 
act", which is simply not the way LPCs work. This whole thread and its 
predecessors are about CRP. I've tried to explain to him that CRP works by 
having the JTAG/Debug pins operate either as a GPIO pins or as JTAG pins, but 
obviously he doesn't care, and is only interested in bashing people.

Actually, Philips themself call the pins "Debug" port. For example in the 
LPC2119, 2129, 2194, 2292 and 2294 user manual on page 120, they describe pin 
P1.26 (RTCK): "LOW on this pin while RESET is LOW enables pins P1.31:26 to 
operate as a Debug port after reset."

Regarding lpc2100_fan's desire to keep his name out of this: Sure, lately this 
is all John Heenan's objections, so lets call it that way.

Kind regards,

Dominic