PIC18F23K22-ESLASHML datasheet(365/496 Pages) MICROCHIP

365 / 496 page

 2010 Microchip Technology Inc.

Preliminary

DS41412C-page 365

PIC18(L)F2X/4XK22

24.3.2

DATA EEPROM

CODE PROTECTION

The entire data EEPROM is protected from external

reads and writes by two bits: CPD and WRTD. CPD

inhibits external reads and writes of data EEPROM.

WRTD inhibits internal and external writes to data

EEPROM. The CPU can always read data EEPROM

under normal operation, regardless of the protection bit

settings.

24.3.3

CONFIGURATION REGISTER

PROTECTION

The Configuration registers can be write-protected.

The WRTC bit controls protection of the Configuration

registers. In normal execution mode, the WRTC bit is

readable only. WRTC can only be written via ICSP or

an external programmer.

24.4

ID Locations

Eight memory locations (200000h-200007h) are

designated as ID locations, where the user can store

checksum or other code identification numbers. These

locations are both readable and writable during normal

execution through the TBLRD and TBLWT instructions

or during program/verify. The ID locations can be read

when the device is code-protected.

24.5

In-Circuit Serial Programming

PIC18(L)F2X/4XK22

devices

can

serially

programmed 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

firmware to be programmed.

24.6

In-Circuit Debugger

When the DEBUG Configuration bit is programmed to

a ‘0’, the In-Circuit Debugger functionality is enabled.

This function allows simple debugging functions when

used with MPLAB® IDE. When the microcontroller has

this feature enabled, some resources are not available

for general use. Table 24-6 shows which resources are

required by the background debugger.

TABLE 24-6:

DEBUGGER RESOURCES

To use the In-Circuit Debugger function of the

microcontroller, the design must implement In-Circuit

Serial Programming connections to the following pins:

•MCLR/VPP/RE3

•VDD

•VSS

•RB7

•RB6

This will interface to the In-Circuit Debugger module

available from Microchip or one of the third party

development tool companies.

24.7

Single-Supply ICSP Programming

The LVP Configuration bit enables Single-Supply ICSP

Programming (formerly known as Low-Voltage ICSP

Programming or LVP). When Single-Supply Program-

ming is enabled, the microcontroller can be programmed

without requiring high voltage being applied to the

MCLR/VPP/RE3 pin. See “PIC18(L)F2XK22/4XK22

Flash Memory Programming” (DS41398) for more

details about low voltage programming.

The LVP bit may be set or cleared only when using

standard high-voltage programming (VIHH applied to

the MCLR/VPP/RE3 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.

I/O pins:

RB6, RB7

Note 1: High-voltage programming is always

available, regardless of the state of the

LVP bit, by applying VIHH to the MCLR

pin.

2: By default,

Single-Supply ICSP

enabled in unprogrammed devices (as

supplied from Microchip) and erased

devices.

3: While in Low-Voltage ICSP mode, MCLR

is always enabled, regardless of the

MCLRE bit, and the RE3 pin can no

longer be used as a general purpose

input.

PIC18F23K22-E/ML Datasheet(PDF) 365 Page - Microchip Technology

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