Cannot reset PIC18 by pulling MCLR low

upand_at_them

Joined May 15, 2010
766
Did you set the MCLR enable bit in the config word? I have no idea what value your R1 is...Is it close to 10K? Are you indeed using the QFN package part?...Different packages have different MCLR pin numbers.
 

Thread Starter

birdtrick

Joined Dec 1, 2016
21
Did you set the MCLR enable bit in the config word? I have no idea what value your R1 is...Is it close to 10K? Are you indeed using the QFN package part?...Different packages have different MCLR pin numbers.
Sorry.. forgot to indicate values. 10k resistor and 100NF cap. Yes, the MCLR enable bit is on. It is QFN.
 

AlbertHall

Joined Jun 4, 2014
11,506
What are you using to program the PIC?
Are there any error/warning messages when compiling/assembling or programming your code?
Post the complete project code.
 

jpanhalt

Joined Jan 18, 2008
11,088
A search this morning of the Microchip site for the 18LF2520 returned:

1607778472406.png

Clicking on documents gives the same message. Are you absolutely sure that is the correct device?

How are you programming it (i.e., low voltage or high voltage?).
 

upand_at_them

Joined May 15, 2010
766
It's been out for a while; Digi-Key carries it. But he should have stated the part in the post instead of relying on us reading the poorly drawn circuit diagram.
 

Thread Starter

birdtrick

Joined Dec 1, 2016
21
Thanks for the help guys. After a long night I tested another chip and it worked fine. The first chip was defective.

My apologies if I didn't post things correctly. I thought I gave the pertinent details but apparently I didn't. I'm an amateur with electronics and forums as well.

Thanks...
 

jpanhalt

Joined Jan 18, 2008
11,088
It is possible to overload MCLR in reset. That is why Microchip gives a recommended circuit with a series resistor. In my experience, it is extremely rare to get a chip from the manufacturer that is defective. That is, I have never had that experience.
 
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