(header added to expand readership. Most people reject missing header
messages)

I understand your problem, and we have ALL had a problem like this at one
time or another.

In my experience, this is caused by one of the multiple VSS or VDD pins
floating. See, internally, some PICs operate in sections (to ease chip
testing), and the pins MUST be attached properly. Make sure that this is
actually performed, by measuring from the GND plane to each pin with a LOW
RANGE OHMMETER. Just using a standard meter is misleading, because the
internal connection can be good enough for a "beep". The connection has to
be 1/10 of an ohm or LESS.

The second place to look is at the oscillator / resonator. If the GND
connection to the phase shifting caps is not good, the oscillator can do
bizarre things.

Report your findings!

--Bob





> Hey,
>
> We discovered a very odd problem with our PIC18LF2520's. When you
> approach the PIC it reboots. With some experimentation we found that
> it's because of sensitivity to static electricity. In other words
> grounding onself it doesn't happen, and deliberate charging causes the
> PIC to reboot at physically further distances depending on the amount of
> charge you're carrying.
>
> This is bad.
>
> Note that the MCLR is configured as an output to an LED, so I don't see
> this as being the reason for the reboot.
>
> Further. We have found that sometimes when you start them they just
> keep resetting. In the main method we have the basic configuration, like
> setting the ports LO, turning on LEDs, configuring the tranceivers, etc.
> There after we print the software name+version to the serial port. When
> watching the serial, all you see is the name+version being printed in a
> loop. The code has no loop wrapping this, and the only way for this to
> happen is if the main method would be repeatedly called, and again the
> only way I can see this happening is with the PIC enter/recovering from
> reset continuously.
>
> This is bad :/
>
> I'm not sure if these 2 problems are related. Though the latter definitely
> makes the system unusable, because once it occurs the only way to fix
> it is to turn it off/on until it starts to act it's age.
>
> Any advice/ideas would be more than appreciated. The engineers over
> here are down on ideas. If you need more info, just specify what and
> I'll send it along.
>
> Quintin Beukes
> --
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>


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