[sdiy] PIC advice needed (OT)

[m.bareille at free.fr]

Yes, the LVP mode cost one pin , the PGM pin.

If by mistake you set the LVP bit to '0' under LVP mode, the only way to
set it back to '1', it is to burn the PIC again  with hi voltage on the
Vpp/MCLR pin. And it is very easy to erase the LVP bit!

So if you do not have a hi-voltage prommer in hand to rescue the situation after
a nice reset of the LVP flag , you are locked.

Most of the cheap PIC prommers sold on ebay are LVP only
... but they are USB !

Cheers,

Marc B.








Selon Colin f <colin at colinfraser.com>:

>
> > PGM is used with the LVP/ICSP mode = low voltage in circuit
> > serial programming.
> > This allow to burn the PIC under +5V only . The Vpp pin is
> > not used in this case to burn the PIC and the LVP flag must
> > be ON , else it will not work...
>
> Is the Vpp/MCLR pin not still required to put the PIC into reset for LVP ?
> I'd stick to the normal programming mode.
> LVP costs you an IO pin, and people seem to have way more trouble with LVP
> than standard ICSP.
>
> When using the MCLR/Vpp pin with a pull-up to the 5v rail, always remember
> to use a diode to protect the 5v rail from the programming voltage.
> Expensive serial DACs don't take 13v supplies well.
>
> Cheers,
> Colin f
>
>
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