Lpc2000

At 05:38 AM 4/29/2006 +0000, jayasooriah wrote:
>--- In lpc2000@yahoogroups.com, Robert Adsett <subscriptions@...> wrote:
> > >I like to know if you think any other ARM licensee is worse.
> >
> > Who said anything about ARM licensees?  If you make a broad
>statement like
> > the above you have to expect a response in kind.
>
>Perhaps I should have said comparing 4-bit controller to 32-bit ARM is
>like comparing apples to oranges :)

Hey, you said unprecedented w/o adding any restriction :)  Yeah 4 bit 
stretches it but that was rather the point I was trying to make.  However 
it does compare nicely with 16 bit and a number of the higher end 8 bit micros.

> > They had to assign the pin somewhere.  No doubt they had their
>reasons for
> > the choice they made.  No matter where they put it, it would have
>caused
> > someone a problem.
>
>Some solutions cause more problem than others.

Well that depends on the perspective, I can certainly think of worse 
choices and effectively eliminating DCD is a pretty minor effect with 
fairly straightforward workarounds if you need DCD.  As far as I'm 
concerned P0.14 has no other purpose than invoking ISP.


> > Um how do you lock out the HW in software?  You always have serial ISP
> > available.
>
>ISP relies on the contents of boot sector being kept intact.
>
>It is possible to erase or corrupt the boot sector given this section
>of on-chip flash is not protected and does not have SDP or equivalent.

SDP??

Ah yes, the corrupted boot block.  You know in the 2 1/2 years I've been 
following this list I've seen I think three reports of boot block 
corruption.  An early report which was basically a friend of a stranger 
report, your report which was the most detailed and one other that was 
later withdrawn .

> > >Having to condition analog input in order to use watchdog is a serious
> > >design defect.  The fix is simple if it were done in the bootloader.
> > >It is the obvious solution.  Saves having endless discussion on how to
> > >solve this defect with yet another gate or chip.
> >
> > What errata is that?  And how do you fix an failure to condition an
>analog
> > input by changing the bootloader?
>
>I think it not in the errata because it is a "feature".
>
>The boot loader sets up external bus interface based on reset
>(includign watchdog reset) by reading digital state of ADC input.
>
>This cannot be a sensible thing to do IMO.

Reference please.  I don't use chips large enough to demand external memory 
(really 256K is luxurious).  I did take a quick look at the 2200's though 
and found boot0 &1 which appear to control the startup bus but they are 
multiplexed with the data lines not A/D inputs.  I only took a quick look 
at a few variants though.

Given that it's true though I fall back to what I said earlier about having 
to take into account startup conditions when you design a system.  That's 
why you have to read both the data sheet and user manual before selecting a 
chip.  Also errata and user experiences.

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/