Microchip Technology MCP1631RD-MCC2 Data Sheet

DS41291G-page 232

 2006-2012 Microchip Technology Inc.

The LVP bit of the Configuration Word enables
low-voltage ICSP programming. This mode allows the
microcontroller to be programmed via ICSP using a
V

DD

 source in the operating voltage range. This only

means that V

PP

 does not have to be brought to V

IHH

 but

can instead be left at the normal operating voltage. In
this mode, the RB3/PGM pin is dedicated to the
programming function and ceases to be a general
purpose I/O pin. During programming, V

DD

 is applied to

the MCLR pin. To enter Programming mode, V

DD

 must

be applied to the RB3/PGM provided the LVP bit is set.
The LVP bit defaults to on (‘1’) from the factory.

If Low-Voltage Programming mode is not used, the LVP
bit can be programmed to a ‘0’ and RB3/PGM becomes
a digital I/O pin. However, the LVP bit may only be
programmed when programming is entered with V

IHH

on MCLR. The LVP bit can only be charged when using
high voltage on MCLR.
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
supplied at 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 calibration
values, unique user IDs or user code can be
reprogrammed or added.

External
Connector
Signals

To Normal
Connections

To Normal
Connections

V

DD

V

SS

RE3/MCLR/V

PP

RB6

RB7

+5V

0V

V

PP

CLK

Data I/O

*

Isolation devices (as required)

Note 1: The High-Voltage Programming mode is

always available, regardless of the state
of the LVP bit, by applying V

IHH

 

to the

MCLR pin.

2: While in Low-Voltage ICSP mode, the

RB3 pin can no longer be used as a
general purpose I/O pin.

3: When using Low-Voltage ICSP Program-

ming (LVP) and the pull-ups on PORTB
are enabled, bit 3 in the TRISB register
must be cleared to disable the pull-up on
RB3 and ensure the proper operation of
the device.

4: RB3 should not be allowed to float if LVP

is enabled. An external pull-down device
should be used to default the device to
normal operating mode. If RB3 floats
high, the PIC16F882/883/884/886/887
devices will enter Programming mode.

5: LVP mode is enabled by default on all

devices shipped from Microchip. It can be
disabled by clearing the LVP bit in the
CONFIG register.