PIC16F870SLASHP datasheet(104/156 Pages) MICROCHIP

104 / 156 page

PIC16F870/871

DS30569A-page 104

Preliminary

11.17

In-Circuit Serial Programming

PIC16F870/871 microcontrollers can be serially pro-

grammed while in the end application circuit. This is

simply done with two lines for clock and data and three

other lines for power, ground, and the programming

voltage. This allows customers to manufacture boards

with unprogrammed devices, and then program the

microcontroller just before shipping the product. This

also allows the most recent firmware or a custom firm-

ware to be programmed.

When using ICSP, the part must be supplied 4.5V to

5.5V if a bulk erase will be executed. This includes

reprogramming of the code protect both from an on-

state to off-state. For all other cases of ICSP, the part

may be programmed at the normal operating voltages.

This means calibration values, unique user IDs or user

code can be reprogrammed or added.

For complete details of serial programming, please

refer to the In-Circuit Serial Programming (ICSP™)

Guide, (DS30277B).

11.18

Low Voltage ICSP Programming

The LVP bit of the configuration word enables low volt-

age ICSP programming. This mode allows the micro-

controller 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 program-

ming function and ceases to be a general purpose I/O

pin. During programming, VDD is applied to the MCLR

pin. To enter programming mode, VDD 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 pro-

grammed when programming is entered with VIHH 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 avail-

able 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 off-state. For all other cases of low volt-

age 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.

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 RB3

pin can no longer be used as a general

purpose I/O pin.

PIC16F870/P Datasheet(PDF) 104 Page - Microchip Technology

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