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Random MCLR Resets on P16F648A

 
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Ali
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Random MCLR Resets on P16F648A
PostPosted: Fri Mar 24, 2006 9:16 am     Reply with quote
I am receiving random MCLR resets both during RUN time and during SLEEP

My circiut in MCLR is as follows (Sorry for the crude drawing)

Code:


3.3V          10K         DIODE     4|
  *---------^^^^------->|------------|  MCLR/CPP/RA5 Input.  on PIC
                                     |        |
                                     |
                                     |                                         
                             To Programming Header



I have 0.1uF caps on the Power Supply pin.

Any one else have similar problems? Any suggestions on how to combat?


Watchdog is enabled
Brownout is disabled
Powerup Timer is enabled
Ali
Guest
PostPosted: Fri Mar 24, 2006 1:57 pm     Reply with quote
OK.. A quick question, Since I only use MCLR for programming and
I do not need an external reset to the processor.
can I just set that pin for I/O only and will that solve my MLCR reset problem?

Then set that pin as an Input.. Since in hardware it is tied to 3.3V. (or so)

Thanks in advance..
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Fri Mar 24, 2006 2:29 pm     Reply with quote
I would get rid of the diode. Most people just use the 10K resistor
to provide isolation between the +13v programming voltage and
the +3.3v generated from the boards own voltage regulator.
This advice is for boards that use the Microchip ICD2 as an in-circuit
programmer.
ckielstra



Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands

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PostPosted: Fri Mar 24, 2006 3:54 pm     Reply with quote
And don't forget the other popular suggestion: Set the NOLVP fuse.
Ali
Guest
PostPosted: Sun Mar 26, 2006 8:58 am     Reply with quote
Thanks for your replies.

I do have NOLVP set, and I will take out the diode and see if it helps the situation. I've done some searching on the site and have seen a few people use resistors in the 4.7 to 1K range? Anyone had to do that for ESD protection in portable devices?

Thanks again for all your help..
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