PIC18F6585 Datasheet, PDF (365/496 Pages) Microchip Technology – 64/68/80-Pin High-Performance, 64-Kbyte Enhanced Flash Microcontrollers with ECAN Module

PIC18F6585/8585/6680/8680
24.8 Low-Voltage ICSP Programming
The LVP bit in Configuration register, CONFIG4L,
enables Low-Voltage ICSP Programming. This mode
allows the microcontroller to be programmed via ICSP
using a VDD source in the operating voltage range. This
only means that VPP does not have to be brought to VIHH
but can instead be left at the normal operating voltage.
In this mode, the RB5/KBI1/PGM pin is dedicated to the
programming function and ceases to be a general pur-
pose I/O pin. During programming, VDD is applied to the
RG5/MCLR/VPP pin. To enter Programming mode, VDD
must be applied to the RB5/KBI1/PGM pin, provided the
LVP bit is set. The LVP bit defaults to a ‘1’ from the
factory.
Note 1: The High-Voltage Programming mode is
always available regardless of the state of
the LVP bit, by applying VIHH to the MCLR
pin.
2: While in Low-Voltage ICSP mode, the
RB5 pin can no longer be used as a
general purpose I/O pin and should be
held low during normal operation.
3: When using Low-Voltage ICSP Program-
ming (LVP) and the pull-ups on PORTB
are enabled, bit 5 in the TRISB register
must be cleared to disable the pull-up on
RB5 and ensure the proper operation of
the device.
4: If the device Master Clear is disabled,
verify that either of the following is done to
ensure proper entry into ICSP mode:
a) disable Low-Voltage Programming
(CONFIG4L<2> = 0); or
b) make certain that RB5/KBI1/PGM is
held low during entry into ICSP.
If Low-Voltage Programming mode is not used, the LVP
bit can be programmed to a ‘0’ and RB5/KBI1/PGM
becomes a digital I/O pin. However, the LVP bit may
only be programmed when programming is entered
with VIHH on RG5/MCLR/VPP.
It should be noted that once the LVP bit is programmed
to ‘0’, only the High-Voltage Programming mode is
available and only High-Voltage Programming mode
can be used to program the device.
When using low-voltage ICSP, the part must be sup-
plied 4.5V to 5.5V if a bulk erase will be executed. This
includes reprogramming of the code-protect bits from
an on-state to an off-state. For all other cases of low-
voltage ICSP, the part may be programmed at the
normal operating voltage. This means unique user IDs
or user code can be reprogrammed or added.
 2004 Microchip Technology Inc.
DS30491C-page 363