At 10:39 AM 22/09/2009, you wrote:
>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.

The second problem sounds like the WDT could be enabled and resetting the
micro, but "sometimes" is odd, so maybe not.

I seriously doubt your engineers have managed to configure /MCLR as an
output unless they have access to some very specialized equipment ;-)
.. it is "input only".. so the LED is obviously not going to be controlled.

If /MCLR is enabled and floating you could see such problems.. especially
if the pin is fitted with an antenna such as a wire to an unused LED.

>Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com



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