At 01:38 PM 2/22/00 -0800, you wrote:
>At 01:19 PM 2/22/00 -0800, you wrote:
>>How about adding the diodes as shown in the data book??
>>We've been using the pullup (47K), diode, and .01 to .1uF cap for a couple
>>of years.
>>Any other experiences with this combination?
>>Kelly
>
>I've been doing this (R and C on MCLR) and I haven't seen any damage to the
>parts.  I'm planning on adding the diode on the next spin of the board,
>because for me to reprogram these suckers with my boot loader I have to
>wait like 10 minutes for the cap to drain (unless I grab it with tweezers).
> The tweezer approach won't work when the boards are conformal coated!  BTW
>I'm using 16F876 parts.
>
>HTH
>

Do you also use R1 (the series R between the cap and MCLR)? With R1
in there, there will probably never be a problem.

Also, if you want to keep the cap, why not add a reset switch to
gnd (with 100 ohm in series)?

Also, as described on my website, I discovered the problem using
UV-erasable /JW parts. The parts would start programming/running
flaky after not too many erasures. After trying everything (new
eraser, fiddling with Vpp & erase times, different download
times, writing bug-free code(!!), on and on), I discovered a
large IR drop across the pullup resistor, so I started using
low value pullups, and pulled the cap off. Also, I don't think
I ever saw the problem with electrically-erasable parts - 16C(F)84s.

- Dan Michaels
Oricom Technologies
http://www.sni.net/~oricom
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