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Lpc2000

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Message

External watchdog and flash loader

2005-10-17 by lhaddix

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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