> Here is what I plan to do once my circuits go from breadboard to PCB:
> (snip)
> The basic deal is that the programming is *physically* isolated from
> the rest of the circuit. 
> (snip)
> As a *hobbyist*, though, I'd probably try to select a uC with enough
> extra pins so that I wouldn't need the jumpers at all, and could just
> leave the programmer in-place for both programming and debugging.

I seldom find it necesarry to 'reserve' the ICSP pins. The rule of thumb
is that when you connect a suitable resistor between each of the PIC
pins PGC, PGD and (on LVP-enabled PICs) PGM and the rest of the circuit
you are OK. For MCLR just a resistor to +5 V will be OK. The minimum
values of these resistors depend on the driving power of the programmer
you use, for my Wisp628 I would say 10k for the PGC/PGD/PGM pins
(although you might get away with 470 ohm), and 33k for the MCLR
pull-up. For a HVP programmer that does not pull PGM low you must take
care of that yourself, just make sure that the pin is low when the PIC
does not drive it. In most cases a 10k pull-down will do it.

Note that some PICs require the infamous 'VPP before VDD/VCC' sequence
to enter program mode. For most of these chips (all?) this will only be
the case if you configure the chip to have internal MCLR, so you might
want to avoid this.

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: www.voti.nl/hvu
 

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