Graham,

I don't believe I've heard of this being done before, and I don't know
whether it
violates any engineering practices or PIC operating specs, but if it works,
I see
no reason why you shouldn't try it, unless one of the above conditions is
true.
You might want to try a cap to ground on the MCLR with a pullup from MCLR to
Vdd.
This will give you the 2 second wait until the power supply stabilizes.   Or
you could
rig up a one shot with a 2 second delay,.  This also would accomplish the
same result,
but would result in extra components, and complexity, as well as extra cost.
The only
other option you would have I guess is to change power suppiles, or at least
try to
speed up the stabilization of the one you have.  One of these method should
be a good
compromise for you between cost, complexity and effectiveness.   The final
decision
is up to you though.  Thanks for the feedback.   I appreciate it.   Sorry
the suggestions
I submitted to you didn't really help as you already had them implemented or
thought of.
Again I would appreciate it if you could let me know what you finally decide
once you get
the circuit fixed the way you want it.  This will not only help in my
projects in the future, but
also in other projects on this list.  You may want to look at the power
supply on a scope to
see just exactly how long it takes to stabilize.  This may help you in
deciding which one of
the above ideas best fits the situation.

Okay, I've taken up enough of your time with this long winded conversation.
I'll let you get
back to PIC'ing.


Later,


Regards,


Jim

-----Original Message-----
From: Graham <grichter@MWEB.CO.ZA>
To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Date: Sunday, May 02, 1999 7:02 AM
Subject: Re: 16F84 PROBLEM


>Hi Jim,
>
>I think I might have found a solution...
>
>I have a 0.1uF decoupling capacitor and pull-ups on, with no WDT. The Power
Up
>Timer is active, and the Oscillator Timer is always on since I'm using a
4Mhz
>Crystal (XT mode). The regulator seems fine at 5.05v.
>
>I have found though that when I apply power while MCLR is low, wait a
couple of
>seconds, then let MCLR go high through a pull-up resistor, it works every
time.
>This could mean that the power line takes that long to stabilize, which is
very
>strange! I could work around this problem by actually attaching my ON/OFF
>switch to MCLR instead of Vdd, and then the device would simply always be
in
>reset when 'off'. Do you think this is a good idea? It seems to solve the
>problem.
>
>Thanks for the ideas.
>Graham