On Tue, Feb 05, 2002 at 02:58:44PM -0500, Kevin Olalde wrote:
> OK, thanks.  I've had a devil of a time getting consistent ISCP results, so
> along with excellent Wouter's suggestions below, are there more 'gotchas'?
>
> Did I read in a thread recently that a fast starting oscillator is also a
> potential problem?  Should I ground the OCS1 while programming?

Maybe. It's a risetime problem. You simply have to get MCLR from 0V to 13V
before the PIC starts executing the first instruction.

>
> I'm guessing I don't need to tie LVP low if I'm using HVP, correct?

Depends on the version. Some early versions had problems with LVP even when
doing HVP programming.

>
> How about breadboards?  Since I'm just starting out, most of my work is done on
> these.  Since I've read here that they are 'big capacitors', is this also a
> source of problems?  Even if no other part of the circuit is connected to RB6
> and RB7.

Not sure. I usually wire wrap. But right now I have one of Wouter's Wloader
dongles on a breadboard. Works fine.

>
> Finally what about the programmer?  Once ISCP programmer I've tried works about
> 10% of the time, on 16F84A and 16F628 parts always in HVP mode.  I recently got
> a ICD, on the same breadboard, same MCLR > 10K R > VCC, it works 100% percent of
> the time on 16F87x parts.  Maybe the inconsistent programmer is getting bit by
> the oscillator issue (I'll go try that now)?

Possibly. I prefer bootloaders because you can always open up a serial
terminal and talk directly to the target. With 16F87X parts I only use a
programmer to download the bootloader.

If you get a minute you can try my trivial LPV programmer. I also worked out
an ICSP interface, but I haven't drawn and uploaded the schematic yet.

http://www.finitesite.com/d3jsys

BAJ
>
> Thanks for any thoughts,
> Kevin
>
> wouter van ooijen & floortje hanneman wrote:
> > sources of ICSP trouble:
> > - load on /MCLR (esp. caps), so the rise from vcc to vpp is too slow
> > - load on any of the involved pins (esp. caps)
> > - not tying LVP enable low
> >
> > When you want to use an RC-reset with ICSP split the R: Vcc - 10k - C -
> > 22k - /MCLR with a diode over the 10k.
>
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