Bob Axtell wrote:
> (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
>>
> 
> 

This can be caused of *any* I/O pin left as an "open input".
Never *ever* do that with *any* CMOS chip.
Since a plain digital I/O pin is input by default, I'd guess
that you have simply "forgot" to switch any unused pins to output.
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist