Lpc2000

At 01:39 AM 12/22/05 +0000, jayasooriah wrote:
>Was Philips misleading us about Code Read Protection?
>
>The preliminary user manual for LPC2119/2129/2194/2292/2294 dated 2004
>May 03 in the section on CRP states:
>
> > When the code read protection is enabled the JTAG debug
> > port, external memory boot and the following ISP commands
> > are disabled:
> >
> > • Read Memory
> > • Write to RAM
> > • Go
> > • Copy RAM to Flash
> >
> > The ISP commands mentioned above terminate with return
> > code CODE_READ_PROTECTION_ENABLED.
> >
> > The ISP erase command only allows erasure of all user
> > sectors when the code read protection is enabled.
>
>Philips stated (by way of poster dated Sat Dec 17, 2005  11:52 AM)
>that the purpose of CRP as:
>
> > Code Read Protection (CRP) was implemented with intention
> > to protect on-chip Flash content from preying eyes.
>
>It appears that Philips made these claims while it knew that CRP can
>be defeated by other methods, including parallel programming or
>booting from external memory.
>
>1/  LPC parts without external memory interface support parallel
>programming.  This method can be used to read and write on-chip flash.

I've seen the hints you provided on this but no real evidence yet.  Since 
this appears to directly contradict what is on Philips Website I remain to 
be convinced.  You need to be able to show that the parts can be parallel 
programmed and that method of programming bypasses the CRP 
features.  Certainly if parallel programming is possible it raises that as 
a possibility since presumably the boot loader would not be involved.

There is another possibility though and that is that you have been the 
victim of marketing manipulation of terms.  It is quite possible that the 
references you have seen to parallel programming are just indicators that 
the devices can be programmed off board with an appropriate programmer and 
that programmer uses either the serial or JTAG ports to do the programming.


>2/  On LPC parts with external memory, it is possible to force the
>part to boot on external memory.  Code in external memory can read and
>write on-chip flash.

Well they do claim that turning on CRP disables the ability to boot from 
external memory.  Do you have any evidence to the contrary?  This does have 
the advantage of being easily tested.  Have you tested it and if so what 
did you use for a test case?  If not, why not?  With a test case this would 
be easy to duplicate and verify.

>If the above claims are not true, it would be a simple matter for
>Philips to say so.  The fact that Philips has chosen to go quiet on
>this issue seems to suggest the claims are indeed true.

Hey give them a bit of a chance.  They do, I think, need to respond.  If 
this is coming out of the blue they may need some time to figure out 
exactly what it is they are responding to.  Also at this season the people 
most able to respond may well be on vacation.

Robert

" 'Freedom' has no meaning of itself.  There are always restrictions,   be 
they legal, genetic, or physical.  If you don't believe me, try to chew a 
radio signal. "  -- Kelvin Throop, III
http://www.aeolusdevelopment.com/