PIC18F4431

22.9Low-Voltage ICSP Programming
The LVP bit in Configuration Register 4L
(CONFIG4L<2>) enables Low-Voltage ICSP Program-
ming (LVP). When LVP is enabled, the microcontroller
can be programmed without requiring high voltage
being applied to the MCLR/VPP pin, but the RB5/PGM
pin is then dedicated to controlling Program mode entry
and is not available as a general purpose I/O pin.
LVP is enabled in erased devices.
While programming using LVP, VDD is applied to the
MCLR/VPP pin as in normal Execution mode. To enter
Programming mode, VDD is applied to the PGM pin.
Note1:High voltage programming is always
available, regardless of the state of the
LVP bit or the PGM pin, by applying VIHH
to the MCLR pin.
2:When Low-Voltage Programming is
enabled, the RB5 pin can no longer be
used as a general purpose I/O pin.
3:When LVP is enabled, externally pull the
PGM pin to VSS to allow normal program
execution.
If Low-Voltage ICSP Programming mode will not be
used, the LVP bit can be cleared and RB5/PGM
becomes available as the digital I/O pin RB5. The LVP
bit may be set or cleared only when using standard high
voltage programming (VIHH applied to the MCLR/VPP
pin). Once LVP has been disabled, only the standard
high voltage programming is available and must be
used to program the device.
Memory that is not code-protected can be erased using
either a block erase, or erased row by row, then written
at any specified VDD. If code-protected memory is to be
erased, a block erase is required. If a block erase is to
be performed when using low-voltage programming,
the device must be supplied with VDDof 4.5V to 5.5V.
Voltage on any pin with respect to VSS (except VDD, MCLR, and RA4)............-0.3V to (VDD + 0.3V)
Voltage on VDD with respect to VSS ........ -0.3V to +7.5V
Voltage on MCLR with respect to VSS (Note 2)...0V to +13.25V
Voltage on RA4 with respect to Vss............0V to +8.5V

ICD2

When the target has its own power supply, the target Vdd is connected to these buffers. This also provides level translation (down to 2V) for low voltage operation.

Всъщност на колко V и кои пинове е LVP i HVP, че нещо съвсем се обърках?
На ICD2 колко волта се подават външно захранване при USB комуникация?

Предстои ми да пробвам да програмирам въпросния чип и не искам да повредя нещо

В момента пиша на 18LF4550.При него ги има съшите истории.Използвам стандартните крака +5В,Маса,клок,данни,ресет.Програмирам го с WinPIC800.Не ползвам low voltage.Захранвам схемата през USB-то на РС-то,но през диод.За ICD2 - свържи го по класическата схема и предполагам че няма да имаш пробеми.
А за чий ти е low voltage ако не е тайна?

Не ми трябва, ама да не оплескам нещо. Въобще не мисля и да пипам регистъра за LVP, но щом са го направили явно се използва за нещо