PIC16F87-ISLASHML datasheet(150/214 Pages) MICROCHIP

150 / 214 page

PIC16F87/88

DS30487B-page 148

Preliminary

 2003 Microchip Technology Inc.

15.18 Low-Voltage ICSP Programming

The LVP bit of the configuration word 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 RB3/PGM pin is dedicated to the pro-

gramming function and ceases to be a general purpose

I/O pin.

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 pro-

grammed when programming mode is entered with

VIHH on MCLR. The LVP bit can only be changed 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 this mode can be used to program

the device.

When using Low-Voltage ICSP, the part must be sup-

plied 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 nor-

mal operating voltage. This means calibration values,

unique user IDs, or user code can be reprogrammed or

added.

The following LVP steps assume the LVP bit is set in the

Configuration register.

Apply VDD to the VDD pin.

Drive MCLR low.

Apply VDD to the RB3/PGM pin.

Apply VDD to the MCLR pin.

Follow with the associated programming steps.

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

Low-Voltage

ICSP

mode

(LVP = 1), 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 PIC16F87/88 device 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.

6: Disabling LVP will provide maximum

compatibility

other

PIC16CXXX

devices.

PIC16F87-I/ML Datasheet(PDF) 150 Page - Microchip Technology

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