Lpc2000

Sten,
What do you mean 'bad foul!!!' my design or this situation?

I think I will add circuitry to inhibit the external watchdog
when P0.14 is low. I also want to inhibit the external watchdog
when my 20pin JTAG is in use. 

What can I sense to tell if the JTAG port is connected to an 
emulator? 

I thought about counting on one of it's many grounds
pulling a pin low, but would rather use something that didn't
depend on certain grounds being connected inside the emulator
pod.

I guess as Marcio points out the larger issue is why are there
situations where the internal watchdog can't reset the micro.
Unfortunately this is probably a feature of the LPC design.

Microchip uses an internal RC for thier watchdog which is not
dependant of the system clock for instance.

I think what happens is it's possible for an ESD hit to stop
the crystal osc on the LPC such that reset is needed to restart
the oscillator, but there can be no watchdog reset without a system 
clock.

I've considered using an external osc to feed the ARM, but don't
wish to do this. I can't be sure it would fix the problem without
mocking it up and then blasting with the static gun, but I know that
toggling reset from outside will restart the clock. 

Landrum


--- In lpc2000@yahoogroups.com, Sten <list@n...> wrote:
>
> Yes, with a LPC2124 we had some similar problems in a design.
> 
> Marcio Zaquela wrote:
> > Did anyone else experience the same problem (the LPC2138 stops 
running and 
> > the wachdog doesn´t restart it) ?
> > 
> > 
> > ----- Original Message ----- 
> > From: "lhaddix" <lhaddix@i...>
> > To: <lpc2000@yahoogroups.com>
> > Sent: Monday, October 17, 2005 8:27 AM
> > Subject: [lpc2000] External watchdog and flash loader
> > 
> > 
> > 
> >>Hi,
> >>I'm working on an LPC2138 design and just moved
> >>into ESD testing. After some ESD hits there was
> >>no damage, but the processor would be left not
> >>running.
> >>
> >>Implementing the internal watchdog didn't fix this.
> >>
> >>Apparently there are ways to nail a 2138 with ESD
> >>that must stop the processor clock and thus also
> >>prevent the internal watchdog from working.
> >>
> >>My solution is an external supervisor chip with a
> >>watchdog function that I would keep strobed with
> >>some line from the micro.
> >>
> >>I know this will work because when an ESD hit 'stuns'
> >>the LPC2138 I can restart it by toggling reset.
> >>
> >>The problem is I want to use the internal flash loader
> >>to do the factory program load for my board.
> >>
> >>The flash loader will not keep my external watchdog strobed
> >>and will not be able to avoid a reset as a result. So the
> >>external watchdog will keep it from working.
> >>
> >>Question: Does the phillips flash loader toggle and pin
> >>regularly that I could use for this strobe?
> >>
> >>Can I hook it somehow to make it pet the dog?
> >>
> >>Any ideas?
> >>
> >>Landrum
> >>
> 
> 
> -- 
> /************************************************
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> ************************************************/
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