C18 manual

MPLAB® C18
C COMPILER
GETTING STARTED

© 2005 Microchip Technology Inc.

DS51295E

Note the following details of the code protection feature on Microchip devices:
•

Microchip products meet the specification contained in their particular Microchip Data Sheet.

•

Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.

•

There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.

•

Microchip is willing to work with the customer who is concerned about the integrity of their code.

•

Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable.”

Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.

Information contained in this publication regarding device
applications and the like is provided only for your convenience
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED,
WRITTEN OR ORAL, STATUTORY OR OTHERWISE,
RELATED TO THE INFORMATION, INCLUDING BUT NOT
LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE,
MERCHANTABILITY OR FITNESS FOR PURPOSE.
Microchip disclaims all liability arising from this information and
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life support systems is not authorized except with express
written approval by Microchip. No licenses are conveyed,
implicitly or otherwise, under any Microchip intellectual property
rights.

Trademarks
The Microchip name and logo, the Microchip logo, Accuron,
dsPIC, KEELOQ, microID, MPLAB, PIC, PICmicro, PICSTART,
PRO MATE, PowerSmart, rfPIC, and SmartShunt are
registered trademarks of Microchip Technology Incorporated
in the U.S.A. and other countries.
AmpLab, FilterLab, Migratable Memory, MXDEV, MXLAB,
PICMASTER, SEEVAL, SmartSensor and The Embedded
Control Solutions Company are registered trademarks of
Microchip Technology Incorporated in the U.S.A.
Analog-for-the-Digital Age, Application Maestro, dsPICDEM,
dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR,
FanSense, FlexROM, fuzzyLAB, In-Circuit Serial
Programming, ICSP, ICEPIC, MPASM, MPLIB, MPLINK,
MPSIM, PICkit, PICDEM, PICDEM.net, PICLAB, PICtail,
PowerCal, PowerInfo, PowerMate, PowerTool, rfLAB,
rfPICDEM, Select Mode, Smart Serial, SmartTel, Total
Endurance and WiperLock are trademarks of Microchip
Technology Incorporated in the U.S.A. and other countries.
SQTP is a service mark of Microchip Technology Incorporated
in the U.S.A.
All other trademarks mentioned herein are property of their
respective companies.
© 2005, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
Printed on recycled paper.

Microchip received ISO/TS-16949:2002 quality system certification for
its worldwide headquarters, design and wafer fabrication facilities in
Chandler and Tempe, Arizona and Mountain View, California in
October 2003. The Company’s quality system processes and
procedures are for its PICmicro® 8-bit MCUs, KEELOQ® code hopping
devices, Serial EEPROMs, microperipherals, nonvolatile memory and
analog products. In addition, Microchip’s quality system for the design
and manufacture of development systems is ISO 9001:2000 certified.

DS51295E-page ii


MPLAB® C18 C COMPILER
GETTING STARTED
Table of Contents
Preface ........................................................................................................................... 1
Chapter 1. Overview
1.1 Introduction ..................................................................................................... 7
1.2 System Requirements .................................................................................... 7
1.3 Quick Directory Tour ...................................................................................... 8
1.4 About the Language Tools ............................................................................. 9

Chapter 2. Installation
2.1 Introduction ................................................................................................... 11
2.2 Installing MPLAB C18 .................................................................................. 11
2.3 Uninstalling MPLAB C18 .............................................................................. 17

Chapter 3. Examples of Use
3.1 Introduction ................................................................................................... 19
3.2 Example 1 .................................................................................................... 20
3.3 Example 2 .................................................................................................... 39
3.4 Example 3 .................................................................................................... 43
3.5 Example 4 .................................................................................................... 46
3.6 Example 5 .................................................................................................... 50
3.7 Example 6 .................................................................................................... 52
3.8 Example 7 .................................................................................................... 56

Glossary ....................................................................................................................... 61
Index ............................................................................................................................. 67
Worldwide Sales and Service .................................................................................... 72


DS51295E-page iii

MPLAB® C18 C Compiler Getting Started

DS51295E-page iv


GETTING STARTED
Preface
NOTICE TO CUSTOMERS
All documentation becomes dated, and this manual is no exception. Microchip tools and
documentation are constantly evolving to meet customer needs, so some actual dialogs
and/or tool descriptions may differ from those in this document. Please refer to our web site
(www.microchip.com) to obtain the latest documentation available.
Documents are identified with a “DS” number. This number is located on the bottom of each
page, in front of the page number. The numbering convention for the DS number is
“DSXXXXXA”, where “XXXXX” is the document number and “A” is the revision level of the
document.
For the most up-to-date information on development tools, see the MPLAB® IDE on-line help.
Select the Help menu, and then Topics to open a list of available on-line help files.

INTRODUCTION
The purpose of this document is to help users get up and running with Microchip’s
MPLAB C18 C compiler. Items discussed in this chapter are:
•
•
•
•
•
•

Document Layout
Conventions Used in this Guide
Recommended Reading
The Microchip Web Site
Development Systems Customer Change Notification Service
Customer Support


DS51295E-page 1

DOCUMENT LAYOUT
This document describes how to install/uninstall MPLAB C18 and provides several
examples of writing C code for PICmicro® microcontroller applications. For a detailed
discussion about basic MPLAB IDE v6.xx functions, refer to the MPLAB IDE on-line
help file.
This document includes:
• Chapter 1: Overview – Defines system requirements and provides a brief
description of the installed programs and directories created by the installation
process.
• Chapter 2: Installation – Provides instructions on how to install the compiler onto
your system. Also provides uninstall instructions.
• Chapter 3: Examples of Use – uses a tutorial style to illustrate effective use of
the MPLAB C18 C compiler. The examples use MPLAB IDE v6.xx with
PIC18F452, PIC18F4620 or PIC18F8720 as the selected device and MPLAB SIM
simulator as a debug tool. Some examples use the additional tools, MPLAB ICD 2
in-circuit debugger, PICDEM™ 2 Plus demo board and the PIC18FXX20 64/80L
TQFP demo board.
- Example 1 demonstrates how to set up and build a project; run, step and set
breakpoints in the example code; and debug the code.
- Example 2 demonstrates the use of the MPLAB C18 peripheral libraries and
the C standard library, as well as the allocation of variables into program
memory.
- Example 3 demonstrates some of the differences between Extended and
Non-extended modes.
- Example 4 demonstrates the allocation of variables in access RAM.
- Example 5 demonstrates the use of interrupt service routines with
MPLAB C18 and provides an example of the use of the MPLAB C18
peripheral libraries.
- Example 6 demonstrates creating large data objects, the use of interrupt
service routines, and reading from and writing to the USART.
- Example 7 demonstrates the use of interrupt priority, reading from and writing
to EEDATA, and mixing interrupt driven and polling peripheral access.
• Glossary – A glossary of terms used in this guide.
• Index – Cross-reference listing of terms, features and sections of this document.

DS51295E-page 2


Preface
CONVENTIONS USED IN THIS GUIDE
This manual uses the following documentation conventions:
DOCUMENTATION CONVENTIONS
Description
Arial font:
Italic characters
Initial caps

Quotes
Underlined, italic text with
right angle bracket
Bold characters
Text in angle brackets < >
Courier font:
Plain Courier

Italic Courier
0bnnnn
0xnnnn
Square brackets [ ]
Curly brackets and pipe
character: { | }
Ellipses...


Represents

Examples

Referenced books
Emphasized text
A window
A dialog
A menu selection
A field name in a window or
dialog
A menu path

MPLAB® IDE User’s Guide
...is the only compiler...
the Output window
the Settings dialog
select Enable Programmer
“Save project before build”

A dialog button
A tab
A key on the keyboard

Click OK
Click the Power tab
Press <Enter>, <F1>

Sample source code
Filenames
File paths
Keywords
Command-line options
Bit values
A variable argument

#define START
autoexec.bat
c:mcc18h
_asm, _endasm, static
-Opa+, -Opa0, 1
file.o, where file can be
any valid filename
0b00100, 0b10

File>Save

A binary number where n is a
binary digit
A hexadecimal number where 0xFFFF, 0x007A
n is a hexadecimal digit
Optional arguments
mcc18 [options] file
[options]
Choice of mutually exclusive errorlevel {0|1}
arguments; an OR selection
Replaces repeated text
var_name [,
var_name...]
Represents code supplied by void main (void)
user
{ ...
}

DS51295E-page 3

RECOMMENDED READING
For more information on included libraries and precompiled object files for the
compilers, the operation of MPLAB IDE and the use of other tools, the following are
recommended reading.
readme.c18
For the latest information on using MPLAB C18 C Compiler, read the readme.c18 file
(ASCII text) included with the software. This readme file contains updated information
that may not be included in this document.
readme.xxx
For the latest information on other Microchip tools (MPLAB IDE, MPLINK™ linker, etc.),
read the associated readme files (ASCII text file) included with the software.
MPLAB® C18 C Compiler User’s Guide (DS51288)
Comprehensive guide that describes the operation and features of Microchip’s
MPLAB C18 C compiler for PIC18 devices.
PIC18 Configuration Settings Addendum (DS51537)
Lists the Configuration Bit Settings for the Microchip PIC18 devices supported by the
MPLAB C18 C compiler’s #pragma config directive and the MPASM’s CONFIG
directive.
MPLAB® IDE V6.XX Quick Start Guide (DS51281)
Describes how to set up the MPLAB IDE software and use it to create projects and
program devices.
MPASM™ User’s Guide with MPLINK™ Linker and MPLIB™ Librarian (DS33014)
Describes how to use the Microchip PICmicro MCU assembler (MPASM), linker
(MPLINK) and librarian (MPLIB).
PICmicro® 18C MCU Family Reference Manual (DS39500)
Focuses on the Enhanced MCU family of devices. The operation of the Enhanced MCU
family architecture and peripheral modules is explained, but does not cover the
specifics of each device.
PIC18 Device Data Sheets and Application Notes
Data sheets describe the operation and electrical specifications of PIC18 devices.
Application notes describe how to use PIC18 devices.
To obtain any of the above listed documents, visit the Microchip web site
(www.microchip.com) to retrieve these documents in Adobe Acrobat (.pdf) format.

DS51295E-page 4


Preface
THE MICROCHIP WEB SITE
Microchip provides online support via our WWW site at www.microchip.com. This web
site is used as a means to make files and information easily available to customers.
Accessible by using your favorite Internet browser, the web site contains the following
information:
• Product Support – Data sheets and errata, application notes and sample programs, design resources, user’s guides and hardware support documents, latest
software releases and archived software
• General Technical Support – Frequently Asked Questions (FAQ), technical
support requests, online discussion groups, Microchip consultant program
member listing
• Business of Microchip – Product selector and ordering guides, latest Microchip
press releases, listing of seminars and events, listings of Microchip sales offices,
distributors and factory representatives

DEVELOPMENT SYSTEMS CUSTOMER CHANGE NOTIFICATION SERVICE
Microchip’s customer notification service helps keep customers current on Microchip
products. Subscribers will receive e-mail notification whenever there are changes,
updates, revisions or errata related to a specified product family or development tool of
interest.
To register, access the Microchip web site at www.microchip.com, click on Customer
Change Notification and follow the registration instructions.
The Development Systems product group categories are:
• Compilers – The latest information on Microchip C compilers and other language
tools. These include the MPLAB C17, MPLAB C18 and MPLAB C30 C compilers;
MPASM™ and MPLAB ASM30 assemblers; MPLINK™ and MPLAB LINK30
object linkers; and MPLIB™ and MPLAB LIB30 object librarians.
• Emulators – The latest information on Microchip in-circuit emulators.This
includes the MPLAB ICE 2000 and MPLAB ICE 4000.
• In-Circuit Debuggers – The latest information on the Microchip in-circuit
debugger, MPLAB ICD 2.
• MPLAB IDE – The latest information on Microchip MPLAB IDE, the Windows®
Integrated Development Environment for development systems tools. This list is
focused on the MPLAB IDE and MPLAB SIM simulators, MPLAB IDE Project
Manager and general editing and debugging features.
• Programmers – The latest information on Microchip programmers. These include
the MPLAB PM3 and PRO MATE® II device programmers and the PICSTART®
Plus development programmer.


DS51295E-page 5

CUSTOMER SUPPORT
Users of Microchip products can receive assistance through several channels:
•
•
•
•
•

Distributor or Representative
Local Sales Office
Field Application Engineer (FAE)
Technical Support
Development Systems Information Line

Customers should contact their distributor, representative or field application engineer
(FAE) for support. Local sales offices are also available to help customers. A listing of
sales offices and locations is included in the back of this document.
Technical support is available through the web site at: http://support.microchip.com
In addition, there is a Development Systems Information Line which lists the latest versions of Microchip's development systems software products. This line also provides
information on how customers can receive currently available upgrade kits.
The Development Systems Information Line numbers are:
1-800-755-2345 – United States and most of Canada
1-480-792-7302 – Other International Locations

DS51295E-page 6


GETTING STARTED
Chapter 1. Overview
1.1

INTRODUCTION
This document is designed to get users started quickly using Microchip’s MPLAB C18
C compiler. PICmicro microcontroller applications can be easily developed using
MPLAB C18 with PIC18 PICmicro MCUs, MPLINK linker and MPLAB IDE. Please refer
to the MPLAB® C18 C Compiler User’s Guide (DS51288) for more details on the
features mentioned in this document. Information in this chapter includes:
• System Requirements
• Quick Directory Tour
• About the Language Tools

1.2

SYSTEM REQUIREMENTS
The minimum system requirements for using MPLAB C18 and the MPLINK linker are:
• 25 MB hard disk space (50 MB recommended)
• Intel Pentium® class PC running Microsoft® Windows® 9x, Windows 2000,
Windows ME®, or Windows XP® operating system


DS51295E-page 7

1.3

QUICK DIRECTORY TOUR
The MPLAB C18 installation directory contains the readme file for the compiler
(readme.c18) and the readme file for the linker (readme.lkr). In addition, a number
of subdirectories are also present. A detailed description of the subdirectories is shown
in Table 1-1.
TABLE 1-1:
Directory

MPLAB C18 SUBDIRECTORY DESCRIPTIONS
Description

bin
cpp

Contains the source code for the MPLAB C18 C preprocessor. This
source code is provided for general interest.

doc

Contains the MPLAB C18 electronic documentation. Refer to these
documents for questions regarding MPLAB C18.

example

Contains sample applications to help users get started using
MPLAB C18, including the examples contained in this document.

h

Contains the header files for the standard C library and the
processor-specific libraries for the supported PICmicro MCUs.

lib

Contains the standard C library (clib.lib or clib_e,lib), the
processor-specific libraries (p18xxxx.lib or p18xxxx_e.lib,
where xxxx is the specific device number) and the startup modules
(c018.o, c018_e.o, c018i.o, c018i_e.o, c018iz.o,
c018iz_e.o).

lkr

Contains the linker script files.

mpasm

Contains the command-line version of the MPASM assembler, the
assembly header files for the devices supported by MPLAB C18
(p18xxxx.inc) and the assembly header files used by the libraries.

src

DS51295E-page 8

Contains the executables for the compiler and linker. These are
described in more detail in the following section.

Contains the source code, in the form of C and assembly files, for the
standard C library, the processor-specific libraries and the startup
modules.


Overview
1.4

ABOUT THE LANGUAGE TOOLS
The bin and mpasm subdirectories of the MPLAB C18 compiler installation directory
contains the executables which comprise the MPLAB C18, MPASM assembler and the
MPLINK linker. A brief description of these programs is shown in Table 1-2.
TABLE 1-2:

MPLAB C18, MPASM ASSEMBLER AND MPLINK LINKER
EXECUTABLES

Executable

Description

mcc18.exe

This is the compiler shell. It takes as input a C file (i.e., file.c)
and invokes the Extended or Non-extended mode compiler
executable.

mcc18-extended.exe

This is the Extended mode compiler executable. It is invoked by
the compiler shell when compiling for Extended mode. It
invokes the preprocessor cpp18.exe to preprocess the C file
and then compiles the preprocessed output and generates a
COFF file (e.g., file.o) to be passed to the linker.

mcc18-traditional.exe This is the Non-extended mode compiler executable. It is
invoked by the compiler shell when compiling for the
Non-extended mode. It invokes the preprocessor cpp18.exe
to preprocess the C file and then compiles the preprocessed
output and generates a COFF file (e.g., file.o) to be passed
to the linker.
cpp18.exe

This is the C preprocessor.

mplink.exe

This is the driver program for the linker. It takes as input a linker
script, object files and library files and passes these to
_mplink.exe. It then takes the output COFF file from
_mplink.exe and passes it to mp2cod.exe and
mp2hex.exe.

_mplink.exe

This is the linker. It takes as input a linker script
(e.g., p18f452.lkr), object files and library files and outputs a
COFF executable (e.g., file.out or file.cof). This COFF
file is the result of resolving unassigned addresses of data and
code of the input object files and referenced object files from
the libraries. _mplink.exe also optionally produces a map file
(e.g., file.map) that contains detailed information on the
allocation of data and code.

mp2cod.exe

This is the COFF to COD file converter. The COD file is a
symbolic debugging file format which is used by the MPLAB
IDE v5.xx. mp2cod.exe takes as input the COFF file produced
by _mplink.exe and outputs a COD file (e.g., file.cod). It
also creates a listing file (e.g., file.lst) that displays the
correspondence between the original source code and machine
code.

mp2hex.exe

This is the COFF to hex file converter. The hex file is a file
format readable by a PICmicro programmer, such as the
PICSTART Plus or the PRO MATE II. mp2hex.exe takes as
input the COFF file produced by _mplink.exe and outputs a
hex file (e.g., file.hex).

mplib.exe

This is the librarian. It allows for the creation and management
of a library file (e.g., file.lib) that acts as an archive for the
object files. Library files are useful for organizing object files
into reusable code repositories.


DS51295E-page 9

TABLE 1-2:

MPLAB C18, MPASM ASSEMBLER AND MPLINK LINKER
EXECUTABLES (CONTINUED)
This is the command-line assembler. It takes as input an
assembly source file (e.g., file.asm) and outputs either a
COFF file (e.g., file.o) or a hex file and COD file
(e.g., file.hex and file.cod). It also creates a listing file
(e.g., file.lst) and an error file (e.g., file.err), which
contains any errors or warnings emitted during the assembly
process. Assembly source files may include assembly header
files (e.g, p18f452.inc), which also contain assembly source
code.

mpasm.exe

More detailed information on the language tools, including their command-line usage,
can be found in the MPLAB® C18 C Compiler User’s Guide (DS51288) and the
MPASM™ User’s Guide with MPLINK™ and MPLIB™ (DS33014).
An example of the flow of execution of the language tools is illustrated in Figure 1-1.
FIGURE 1-1:

LANGUAGE TOOLS EXECUTION FLOW
LEGEND

Source
Files

Input.asm

Object
Files

Input.o

mcc18.exe

File

Input2.c

mcc18.exe

cpp18.exe

mpasm.exe

Input1.c

cpp18.exe

Input1.o

Input3.o

Program

Input2.o

mplib.exe

Library and
Linker Script
Files

lib1.lib

script.lkr

mplink.exe
_mplink.exe

Output
Files

output.map

mp2cod.exe

output.hex

output.out

output.lst

DS51295E-page 10

mp2hex.exe

output.cod


GETTING STARTED
Chapter 2. Installation
2.1

INTRODUCTION
This chapter will discuss in detail how to install MPLAB C18. Should it become
necessary to remove the software, uninstall directions are provided as well. Information
discussed in this chapter includes:
• Installing MPLAB C18
• Uninstalling MPLAB C18

2.2

INSTALLING MPLAB C18
To install MPLAB C18, run the setup program from the CD-ROM. If installing an MPLAB
C18 upgrade, run the upgrade setup program downloaded from the Microchip web site.
A series of dialogs will step through the setup process.

2.2.1

Welcome

A welcome screen displays the version number of MPLAB C18 that the setup program
will install, Figure 2-1.
MPLAB C18 WELCOME SCREEN

N

ee
ds

U
pd

at

in

g

FIGURE 2-1:

Click Next to continue.


DS51295E-page 11

2.2.2

Readme File

The MPLAB C18 readme file is displayed. This file contains important information about
this release of MPLAB C18, such as known bugs, Figure 2-2.
FIGURE 2-2:

MPLAB C18 README FILE

After reviewing, click Next to continue.

2.2.3

Select Installation Directory

This step allows users to choose the directory where MPLAB C18 will be installed.
When installing MPLAB C18 for the first time, the default installation directory is
C:mcc18, as shown in Figure 2-3.
If an upgrade is being installed, the setup program attempts to set the default
installation directory to the directory of the previous installation. The installation
directory for an upgrade must be the same directory of the previous installation or
upgrade.
Note:

DS51295E-page 12

Files in the installation directory and its subdirectories may be overwritten
or removed during the installation process. To save any files, such as
modified linker scripts or library source code from a previous installation,
copy those files to a directory outside the installation directory before
continuing.


Installation
FIGURE 2-3:

MPLAB C18 SELECT INSTALLATION DIRECTORY

After specifying the directory, click Next.

2.2.4

Select Components

Choose the components to be installed by checking the appropriate box, Figure 2-4.
FIGURE 2-4:

MPLAB C18 SELECT COMPONENTS

A detailed description of the available components is shown in Table 2-1.


DS51295E-page 13

TABLE 2-1:

MPLAB C18 SOFTWARE COMPONENTS

Component

Description

Program files

Assembler files

These include the command-line version of the MPASM assembler
(mpasm.exe), the assembly header files for the devices supported by
MPLAB C18 (p18xxxx.inc) and the assembly header files used by
the libraries.

Linker script files

These files are used by the MPLINK linker. There is one file for each
supported PICmicro microcontroller. Each file provides a default
memory configuration for the processor and directs the linker in the
allocation of code and data in the processor’s memory.
These linker scripts differ from the linker scripts provided with the
MPLAB IDE in that these are specifically designed for use with MPLAB
C18. Since the MPLINK linker requires a linker script, users should
install this component unless they plan on creating their own linker
scripts.

Standard headers

These are the header files for the standard C library and the
processor-specific libraries. If users choose to install the standard
libraries, these will also be installed.

Standard libraries

This component contains the standard C library, the processor-specific
libraries, and the startup modules. See the MPLAB® C18 C Compiler
Libraries (DS51297) and the MPLAB® C18 C Compiler User’s Guide
(DS51288) for more information on the libraries and startup modules.
Since most typical programs use the libraries and a startup module, it
is recommended that users install this component.

Documentation

This is the electronic documentation for MPLAB C18.

Examples

These are sample applications to assist users in getting started with
MPLAB C18, including the examples described in this document.

Library source code

This is the source code for the standard C library and the
processor-specific libraries. Users should install this component if they
plan on rebuilding the libraries.

Preprocessor source
code

DS51295E-page 14

These are the executables for the compiler and linker. Users should
install this component unless they are upgrading and wish to use the
executables from the previously installed version.

This is the source code for the preprocessor. It is provided for general
interest.


Installation
2.2.5

Configuration Options

The next dialog screen allows users to select a particular set of MPLAB C18
configuration options for their system, Figure 2-5:
FIGURE 2-5:

MPLAB C18 CONFIGURATION OPTIONS

A detailed description of the available configuration options is shown in Table 2-2.
Select the components to be installed, then click Next.


DS51295E-page 15

TABLE 2-2:

MPLAB C18 CONFIGURATION OPTIONS

Configuration

Description

Add MPLAB C18 to PATH
environment variable

Add MPASM to PATH
environment variable

This adds the path of the MPASM executable (mpasm.exe)
to the front of the PATH environment variable. Doing this
allows users to launch the newly installed version of the
MPASM assembler at the command shell prompt from any
directory.

Add header file path to
MCC_INCLUDE environment
variable

This adds the path of the MPLAB C18 header file directory to
the front of the MCC_INCLUDE environment variable. If this
variable does not exist, it is created. MCC_INCLUDE is a list of
semi-colon delimited directories that MPLAB C18 will search
for in a header file if it cannot find the file in the directory list
specified with the -I command-line option. Selecting this
configuration option means users will not have to use the -I
command-line option when including a standard header file.

Modify PATH and
MCC_INCLUDE variables for
all users

This option appears only if users are logged into a Windows
NT® or Windows 2000 computer as an administrator. Selecting this configuration will perform the modifications to these
variables as specified in the three previous options for all
users. Otherwise, only the current user’s variables will be
affected.

Update MPLAB IDE v6.xx to
use this MPLAB C18

This option appears only if the MPLAB IDE v6.xx is installed
on your system. Selecting this option configures the MPLAB
IDE v6.xx to use the newly installed MPLAB C18. This
includes using the MPLAB C18 library directory as the default
library path for MPLAB C18 projects in the MPLAB IDE v6.xx.

Update MPLAB IDE v6.xx to
use this MPLINK linker

DS51295E-page 16

This adds the path of the MPLAB C18 executable
(mcc18.exe) and the MPLINK linker executable
(mplink.exe) to the front of the PATH environment variable.
Doing this allows users to launch the newly installed version
of MPLAB C18 and the MPLINK linker at the command shell
prompt from any directory.

This option appears only if the MPLAB IDE v6.xx is installed
on your system. Selecting this option configures the MPLAB
IDE v6.xx to use the newly installed MPLINK linker.


Installation
2.2.6

Start Installation

The next dialog screen launches the installation, Figure 2-6. Once the Next button is
pressed, all files in the installation directory and its subdirectories will be overwritten or
removed.
FIGURE 2-6:

2.2.7

MPLAB C18 START INSTALLATION

Complete Installation

MPLAB C18 has now been successfully installed. In the “Installation Complete” dialog,
click Finish.
For MPLAB C18 to operate properly, it may be necessary to restart the computer. If the
“Restart Computer” dialog appears, select Yes to restart immediately, or No to restart
the computer at a later time.

2.3

UNINSTALLING MPLAB C18
To uninstall MPLAB C18, open the Windows control panel and launch “Add/Remove
Programs”. Select the MPLAB C18 installation in the list of programs and follow the
directions to remove the program. This will remove the MPLAB C18 directory and its
contents from the computer.
Note:


If uninstalling an upgraded version of MPLAB C18, the entire installation
will be removed; MPLAB C18 cannot be “downgraded”.

DS51295E-page 17

NOTES:

DS51295E-page 18


GETTING STARTED
Chapter 3. Examples of Use
3.1

INTRODUCTION
The following examples are intended to illustrate the effective use of MPLAB C18,
including how to create and build projects and how to step through programs.
These examples assume that MPLAB C18 and MPLAB IDE v6.xx are installed. Some
examples assume MPLAB ICD 2 is installed and connected to a PICDEM™ 2 Plus
demo board with a PIC18F452 device. Please refer to the PIC18FXX2 Data Sheet
(DS39564) for information regarding processor-specific items such as the special
function registers, instruction set and interrupt logic.
Examples presented in this chapter for using MPLAB C18 include:
• Example 1 demonstrates how to set up and build a project; run, step and set
breakpoints in the example code; and debug the code.
• Example 2 demonstrates the use of the MPLAB C18 peripheral libraries and the
C standard library, as well as the allocation of variables into program memory.
• Example 3 demonstrates some of the differences between Extended and
Non-extended modes.
• Example 4 demonstrates the allocation of variables in access RAM.
• Example 5 demonstrates the use of interrupt service routines with MPLAB C18
and provides an example of the use of the MPLAB C18 peripheral libraries.
• Example 6 demonstrates creating large data objects, the use of interrupt service
routines, and reading from and writing to the USART.
• Example 7 demonstrates the use of interrupt priority, reading from and writing to
EEDATA, and mixing interrupt driven and polling peripheral access.


DS51295E-page 19

3.2

EXAMPLE 1
This example is designed for use with the MPLAB IDE v6.xx, the MPLAB SIM simulator
and the PIC18F452 device. It shows how to set up an MPLAB C18 project in the
MPLAB IDE, build the project and step through the source code using the MPLAB SIM
simulator. Additionally, running the program using the MPLAB ICD 2 with the
PICDEM 2 Plus demo board is demonstrated. The example assumes that the directory
c:mcc18 is the MPLAB C18 installation directory.
Here is the source code for the example:
#include <p18cxxx.h>

/* for TRISB and PORTB declarations */

/* Set configuration bits for use with ICD2 / PICDEM2 PLUS Demo Board:
* - set HS oscillator
* - disable watchdog timer
* - disable low voltage programming
*/
#pragma config OSC = HS
#pragma config WDT = OFF
#pragma config LVP = OFF
int counter;
void main (void)
{
counter = 1;
TRISB = 0;
/* configure PORTB for output */
while (counter <= 15)
{
PORTB = counter;
/* display value of 'counter' on the LEDs */
counter++;
}
}

• TRISB and PORTB are special function registers on the PIC18F452 device. The
PORTB pins are connected to the LEDs on the PICDEM 2 demo board; the
TRISB pins configure the PORTB pins for input (1) or output (0).
• The configuration bits need to be set appropriately; this is done by utilizing the
#pragma config directive with settings for each configuration byte. This
includes specifying the oscillator used on the PICDEM 2 Plus demo board; in the
example, the crystal (OSC=HS) is used. Additionally, MPLAB ICD 2 requires that
the Watchdog Timer and low-voltage programming be disabled (WDT=OFF and
LVP=OFF, respectively). The available configuration bit settings are listed in the
PIC18 Configuration Settings Addendum (DS51537).

DS51295E-page 20


Examples of Use
3.2.1

Setting Up the Project

Select Project>New to create a new project. Then enter the name and directory of the
project in the dialog that displays and click OK, Figure 3-1.
If the examples with MPLAB C18 were installed, then the
examplegetting_startedexample1 subdirectory of the MPLAB C18
installation will already contain the source file for this example.
FIGURE 3-1:

Note:

NEW PROJECT DIALOG

The project name does not have to be the same as the directory name.

The project tree will now be visible with a branch for each type of project file.
FIGURE 3-2:

3.2.2

PROJECT TREE

Select Target Processor

The target processor must be selected before anything else is done with the project.
This is accomplished by choosing Configure>Select Device.
FIGURE 3-3:


SELECT DEVICE OPTION

DS51295E-page 21

For this example, the PIC18F452 device will be used. Select the device and click OK.
FIGURE 3-4:

3.2.3

SELECT DEVICE DIALOG

Select Project Settings

The MPLAB IDE needs to know which compiler and linker to use. To select MPLAB C18
and the MPLINK linker, first choose Project>Select Language Toolsuite.
FIGURE 3-5:

DS51295E-page 22

SELECT LANGUAGE TOOLSUITE OPTION


Examples of Use
A dialog appears to select the language toolsuite. To use the language tools that
include MPLAB C18 and the MPLINK linker, select “Microchip C18 Toolsuite” as the
active toolsuite.
FIGURE 3-6:

SELECT LANGUAGE TOOLSUITE DIALOG

Then, select “MPLINK Object Linker” and “MPLAB C18 C Compiler” and make sure
that the paths are to the newly installed versions of the executables, mplink.exe and
mcc18.exe, respectively. Click OK.
FIGURE 3-7:

Note:


TOOLSUITE CONTENTS

If the user chose to update the MPLAB IDE 6.xx to use the newly installed
compiler and linker in the MPLAB C18 setup program, these paths should
already be set up correctly.

DS51295E-page 23

The next step is to set the command-line options for the compiler and linker. Choose
Project>Build Options>Project.
FIGURE 3-8:

DS51295E-page 24

PROJECT BUILD OPTIONS


Examples of Use
Enter the paths of the header file and library subdirectories of the MPLAB C18
installation directory on the “General” tab as shown in Figure 3-9. The paths can be
typed or click on Browse to designate the path. MPLAB C18 will search for included
.h files in the specified header file directory. The MPLINK linker will search for object
and library files, including those specified in the linker script, in the library directory.
“Output Directory” is the final destination for files that result only from a complete build
of the project –- the .cod, .cof and .hex files. Leave “Output Directory” blank; as a
result, the output file (example1.cof) will be placed in the project directory.
“Intermediates Directory” is where the object files produced by the compiler will be
placed. Leave this entry blank as well; as a result, the object file (example1.o) will be
placed in the same directory as the source file.
The MPLINK linker will search the directory specified in “Linker-Script Path” for linker
scripts. Since the location of the linker script will be specified when it is added to the
project tree, this entry can also be left blank for this example.
FIGURE 3-9:


BUILD OPTIONS, GENERAL TAB

DS51295E-page 25

3.2.4

Select Compiler and Linker Settings

The various command-line options which are passed to the compiler and linker can be
set on the “MPLAB C18” and “MPLINK Linker” tabs, respectively, in the Build Options
window. For this example, the default command-line options for MPLAB C18 will be
accepted.
FIGURE 3-10:

BUILD OPTIONS, MPLAB C18 TAB

By default, when the MPLINK linker is run from the MPLAB IDE, it will not generate a
map (example1.map) file. Change this by selecting “Generate map file” on the
“MPLINK Linker” tab. Click OK. The default settings will be used for the remainder of
the command-line options.
FIGURE 3-11:

DS51295E-page 26

BUILD OPTIONS, MPLINK LINKER TAB


Examples of Use
3.2.5

Add Files to Project

The C source file must be added to the project. Click the right mouse button on “Source
Files” in the project window. Select “Add Files”.
FIGURE 3-12:

SOURCE FILES, ADD FILES OPTION

If c:mcc18examplegetting_startedexample1 was chosen as the project
directory, the source file example1.c already exists there. Browse to this directory and
select the file example1.c. Click Open to add the file to the project.
FIGURE 3-13:

ADD FILES DIALOG

The source file should appear in the project tree.
FIGURE 3-14:


SOURCE FILE IN PROJECT TREE

DS51295E-page 27

The header file is specified in the C source file; therefore no file needs to be added to
“Header Files” in the project tree. A header file may be added to “Header Files” for
convenient viewing of the file, but it is only required that the header file be included in
the C source code to build the project. The required startup module, standard library
and processor library are specified in the linker script, and so no file needs to be added
to “Object Files” or “Library Files” in the project tree. If there were other object files or
library files to link in the project, they would be added under these branches.
The MPLINK linker requires a linker script to be specified. Click the right mouse button
on “Linker Scripts” in the project window, and select Add Files.
FIGURE 3-15:

LINKER SCRIPTS, ADD FILES OPTION

Use the linker script 18f452.lkr in the lkr subdirectory of the MPLAB C18
installation directory. This script is for the PIC18F452 device.
Click Open to add the file to the project tree.
FIGURE 3-16:

DS51295E-page 28

LINKER SCRIPT, ADD FILES DIALOG


Examples of Use
3.2.6

Build the Project

Select Project>Build All to compile and link the project. If there are any error or warning
messages, they will appear in the output window.
FIGURE 3-17:

BUILD ALL OPTION

For this example, the output window should display no errors and a message stating
the output file was successfully built should be visible. If there were any errors, check
to see that the content of the source file matches the program text displayed at the
beginning of Section 3.2 “Example 1”.
FIGURE 3-18:


OUTPUT FOR EXAMPLE 1

DS51295E-page 29

3.2.7

Debugging with the MPLAB SIM Simulator

With the MPLAB SIM Simulator, breakpoints can be set in the source code to observe
the value of variables with a watch window. First, make sure that the MPLAB SIM
Simulator is selected as the debugging tool by selecting Debugger>Select
Tool>MPLAB SIM.
FIGURE 3-19:

SELECT DEBUGGER, MPLAB SIM OPTION

Open the source file by double clicking on it in the project tree. In the source file, place
the cursor over the line where the breakpoint is desired to be set, and click the right
mouse button. Select “Set Breakpoint”.
FIGURE 3-20:

DS51295E-page 30

SET BREAKPOINT OPTION


Examples of Use
The red dot in the gutter along the side of the source window indicates that the
breakpoint has been set and is enabled.
FIGURE 3-21:

BREAKPOINT ENABLED

To open a watch window on the variable counter, select View>Watch.
FIGURE 3-22:


VIEW, WATCH WINDOW OPTION

DS51295E-page 31

Select counter from the menu next to Add Symbol, and click Add Symbol.
FIGURE 3-23:

WATCH WINDOW

Click Run on the toolbar

to run the program.

The program should halt just before the statement at the breakpoint is executed. The
green arrow in the gutter of the source window points to the next statement to be
executed. The watch window should show counter with a value of 1.
FIGURE 3-24:

DS51295E-page 32

WATCH WINDOW COUNTER AT 1


Examples of Use
Click Run again to continue the program. Execution should halt again at the
breakpoint. The watch window should show counter with a value of 2.
FIGURE 3-25:

WATCH WINDOW COUNTER AT 2

To step through the source code one statement at a time, use Step Into on
the toolbar. As each statement executes, the green arrow in the gutter of
the source window moves to the next statement to be executed.
If the program is running, it can be halted by clicking Halt on the toolbar


.

DS51295E-page 33

3.2.8

Map and Listing Files

The map file (example1.map) and listing file (example1.lst) are present in the
project directory and may be opened by selecting File>Open, and then browsing to the
project directory. These files provide additional information which may be useful in
debugging, such as details of allocation of variables and the correspondence between
machine code and source code. For example, the map file shows that the variable
counter has been allocated to address 0x80 in data memory, and it was defined in
example1.c as a non-static global variable, thus giving it external linkage (visibility to
other modules).
EXAMPLE 3-1: MAP FILE
Name
--------counter

Symbols - Sorted by Address
Address
Location
Storage File
--------- --------- --------- ---------------------------0x00008a
data
extern c:mcc18getting_startedexample1example1.c

The listing file shows the machine code generated for each statement the main
function. For each instruction, its address, raw value and disassembly is displayed.
EXAMPLE 3-2:
Address
-------

Value
-------

LISTING FILE
Disassembly
-------------------

0000e2
0000e4
0000e6
0000e8
0000ea
0000ec
0000ee
0000f0
0000f2
0000f4
0000f6
0000f8
0000fa
0000fc
0000fe
000100
000102
00010e

0e01
0100
6f8a
6b8b
6a93
518b
0a00
aee8
d002
358b
d005
0e0f
80d8
558a
0e00
558b
e306
d7ee

MOVLW
MOVLB
MOVWF
CLRF
CLRF
MOVF
XORLW
BTFSS
BRA
RLCF
BRA
MOVLW
BSF
SUBFWB
MOVLW
SUBFWB
BNC
BRA

0x1
0x0
0x8a,0x1
0x8b,0x1
0x93,0x0
0x8b,0x0,0x1
0x0
0xe8,0x7,0x0
0xf8
0x8b,0x0,0x1
0x102
0xf
0xd8,0x0,0x0
0x8a,0x0,0x1
0x0
0x8b,0x0,0x1
0x110
0xec

000104
000106
000108
00010a
00010c

c08a
ff81
2b8a
0e00
238b

MOVFF

0012

RETURN 0x0

int counter;
void main (void)
{
counter = 1;

0x8a,0xf81

000110

Source
---------------------------------------------------------#include <p18cxxx.h> /* for TRISB and PORTB declarations */

TRISB = 0;
/* configure PORTB for output */
while (counter <= 15)

{
PORTB = counter;

INCF
0x8a,0x1,0x1
MOVLW 0x0
ADDWFC 0x8b,0x1,0x1

/* display 'counter' on the LEDs */

counter++;
}

DS51295E-page 34

}


Examples of Use
3.2.9

Debugging with the MPLAB ICD 2

The MPLAB ICD 2 can be used to actually program the device and step through the
application. To do this, the project must be rebuilt with a linker script designed for use
with the MPLAB ICD 2. In the project window, click the right mouse button on the file
18f452.lkr under “Linker Scripts”, and click Remove.
FIGURE 3-26:

LINKER SCRIPTS, REMOVE OPTION

Add the linker script file 18f452i.lkr from the lkr subdirectory of the MPLAB C18
installation directory under “Linker Scripts” in the project tree. This linker script allocates
memory for resources used by the MPLAB ICD 2. The ‘i’ in the file’s name indicates
this linker script is for use with the MPLAB ICD 2.
Rebuild the project by selecting Project>Build All.
To use the MPLAB ICD 2, select Debugger>Select Tool>MPLAB ICD 2.
FIGURE 3-27:


SELECT DEBUGGER, MPLAB ICD 2 OPTION

DS51295E-page 35

To connect to the MPLAB ICD 2, choose Debugger>Connect. See the MPLAB ICD 2
documentation for information on how to configure the MPLAB ICD 2 connection
settings.
FIGURE 3-28:

DEBUGGER, CONNECT OPTION

The output window should show that the MPLAB ICD 2 passed its self-test and is ready
to be programmed. If any errors occur, refer to documentation for the MPLAB ICD 2.
FIGURE 3-29:

DS51295E-page 36

MPLAB ICD 2 OUTPUT


Examples of Use
To program the device, select Debugger>Program.
FIGURE 3-30:

Note:

DEBUGGER, PROGRAM OPTION

Programming the device requires reducing the program memory space
available to allow for MPLAB ICD 2 resources, disabling low voltage
programming and disabling the Watchdog Timer. If an MPLAB ICD 2
Warning dialog is received concerning any of these issues, simply click
OK to proceed.

The output window should show that the programming operation succeeded.
FIGURE 3-31:


OUTPUT WINDOW, PROGRAMMING SUCCEEDED

DS51295E-page 37

A breakpoint may be set in the source file as demonstrated for the MPLAB SIM
Simulator. When Run on the toolbar is clicked, the program halts immediately after the
statement where the breakpoint has been executed.
Note:

This is different than the MPLAB SIM Simulator, which halts before the
statement where the breakpoint is executed. The green arrow points to
the next statement to be executed.

FIGURE 3-32:

HALT AT BREAKPOINT

The PORTB register has been assigned the value of 1. The LEDs on the PICDEM 2 Plus
demo board, which are multiplexed with the PORTB pins, should display the binary
representation of 1.
Note:

The J6 connection on the demo board must be jumpered in order to
connect the PORTB pins with the LEDs.

Each time Run on the toolbar is clicked, execution halts after the assignment to PORTB
and the value on the LEDs should reflect the incriminated value of the counter.

DS51295E-page 38


Examples of Use
3.3

EXAMPLE 2
This example is designed for use with the MPLAB IDE v6.xx, the MPLAB ICD 2, the
PICDEM 2 Plus demo board and the PIC18F452 device. It demonstrates the use of the
MPLAB C18 peripheral libraries and the C standard library. It also demonstrates the
allocation of variables into program memory. The program cycles through a list of
strings, each representing a number from 0 to 15. Each string is converted into its
integer representation for display on the LEDs. The program pauses after displaying
each number to give the user an opportunity to observe the LEDs. For this program,
the J6 connection on the PICDEM 2 Plus demo board must be jumpered.
• MPLAB C18 places string literals in program memory; therefore, the rom keyword
is required in the declaration of the array string_table. The const keyword
alone will not place the data in program memory; the rom keyword is required.
Since program memory in general cannot be modified without additional
specialized code, the const keyword is appropriate.
LVP=OFF, respectively). Finally, since this example exclusively uses the MPLAB
ICD 2, background debugging should always be enabled (DEBUG=ON). The
available configuration bit settings are listed in the PIC18 Configuration Settings
Addendum (DS51537).
• The standard C library function atoi, which converts the string to an integer
representation, expects a character pointer located in data memory. However, as
the string literals are in program memory, they must be copied to data memory
first. The function strcpypgm2ram, which is an MPLAB C18 variant of strcpy,
does just that.
• The PORTB register, which is connected to the LEDs on the PICDEM 2 demo
board, and the TRISB register, which configures the PORTB pins for input or
output, are declared in the processor-specific header file p18f452.h.
• MPLAB C18 provides several functions which provide delays of various lengths,
such as Delay10RTCYx used below. See the header file delays.h for more
details.


DS51295E-page 39

This example can be built and linked in the MPLAB IDE v6.xx and used with the
MPLAB ICD 2 by following the steps in Example 1.
Note:

When compiling with the small code model, MPLAB C18 may emit a
warning about a type qualifier mismatch in an assignment with respect to
the call of strcpypgm2ram. This happens because the second argument
passed to the function is a pointer to near program memory, while the
parameter’s type in the function prototype is a far program memory
pointer. Since the conversion from a near pointer to a far pointer is always
safe, this warning can be ignored. Alternatively, the warning may be
eliminated by compiling with the large code model (at the expense of
possibly a larger code image). To do this, choose “Build Options” and then
“Project” from the “Project” menu. Select “MPLAB C18” and choose
“Memory Model” from the drop-down menu. Finally, select the large code
model.

FIGURE 3-33:

DS51295E-page 40

MEMORY MODEL OPTION


Examples of Use
FIGURE 3-34:

#include
#include
#include
#include

LARGE CODE MODEL OPTION

<string.h>
<stdlib.h>
<delays.h>
<p18cxxx.h>

/*
/*
/*
/*

for
for
for
for

'strcpypgm2ram'
'atoi'
'Delay10KTCYx'
'PORTB' and 'TRISB'

*/
*/
*/
*/

/* MPLAB C18 places string literals in program memory */
#define STRING_TABLE_SIZE 16
const rom char *string_table[STRING_TABLE_SIZE] =
{ "0", "1", "2", "3",
"4", "5", "6", "7",
"8", "9", "10", "11",
"12", "13", "14", "15"
};
* - enable background debugging
*/
#pragma config DEBUG = ON
void main (void)
{
int index;
int integer;
char string[3];
PORTB = 0;
TRISB = 0;


/* configure all PORTB pins for output */

DS51295E-page 41

for (index = 0; index < STRING_TABLE_SIZE; index++)
{
/* copy the string from program memory to data memory for 'atoi' */
strcpypgm2ram (string, string_table[index]);
/* get the number's integer representation from its string
* representation */
integer = atoi (string);
PORTB = integer;
/* output the value to the LEDs */
Delay10KTCYx (255); /* pause for a moment (255 * 10,000 cycles) */
}
}

DS51295E-page 42


Examples of Use
3.4

EXAMPLE 3
Beginning with v2.30, MPLAB C18 supports the PIC18 devices’ Extended mode, which
is targeted toward smaller code size for reentrant code; however, not all PIC18 devices
support the Extended mode. See the device data sheet for more details and other
implications.
This example is designed for use with the MPLAB IDE v6.xx, the MPLAB ICD 2, the
PICDEM 2 Plus demo board and the PIC18F4620 device. This example builds on
Example 2 and demonstrates some of the differences between Extended and
Non-extended mode.

3.4.1

Selecting the Processor

This example will utilize the PIC18F4620 device as the target processor. Steps to select
the target processor can be found in Example 1.

3.4.2

Utilizing the Extended Mode

MPLAB C18, by default, operates in Non-extended mode and it generates code that
will work on a device operating in Non-extended mode. This default behavior can be
changed with the command-line option --extended. To make this change, choose
Project>Build Options>Project and click on the MPLAB C18 tab. Then, click in the
Extended Mode checkbox to enable Extended mode. Click OK.
FIGURE 3-35:



DS51295E-page 43

FIGURE 3-36:

SETTINGS FOR EXTENDED MODE

Up to four different types of linker scripts are distributed with the MPLAB C18 C
compiler for each processor. These linker scripts are different from those distributed
with the MPLAB IDE in that they automatically link in the compiler startup code and
libraries, as well as setting aside a stack area. The four linker scripts distributed for the
PIC18F4620 processor are:
For use with applications compiled in Non-extended mode.
For use with applications compiled in Non-extended mode and being
debugged with the MPLAB ICD 2. The “i” represents that this linker
script allocates memory for resources used by the MPLAB ICD 2.
18f4620_e.lkr
For use with applications compiled in Extended mode.
18f4620i_e.lkr For use with applications compiled in Extended mode and being
debugged with the MPLAB ICD 2. The “i” represents that this linker
script allocates memory for resources used by the MPLAB ICD 2.
18f4620.lkr
18f4620i.lkr

DS51295E-page 44


Examples of Use
For this portion of the example, the 18f4620i_e.lkr must be added to the project
files of the MPLAB IDE project. See Section 3.2 “Example 1” for information on how
to add files to a project.
Next, the __EXTENDED18__ predefined macro will be utilized to set up the
configuration words. The following should be added to the configuration settings
section of Example 2:
#ifdef __EXTENDED18__
#pragma config XINST = ON
#else
#pragma config XINST = OFF
#endif

The above code will enable the Extended mode instructions when compiling in the
Extended mode, and disable the Extended mode instructions when compiling in
Non-extended mode.

3.4.3

Utilizing the Non-extended Mode

To change the above example from Extended mode to Non-extended mode, the
following steps must occur:
1. Disable Extended mode. Choose Project>Build Options>Project and click on the
MPLAB C18 tab. Then, if the Extended Mode checkbox has a check in it, clear
the checkbox by clicking on it. Click OK.
FIGURE 3-37:

SETTINGS FOR NON-EXTENDED MODE

2. Remove the Extended mode, MPLAB ICD 2 linker script (18f4620i_e.lkr)
from the MPLAB IDE project.
3. Add the Non-extended mode, MPLAB ICD 2 linker script (18f4620i.lkr) to the
MPLAB IDE project.


DS51295E-page 45

3.5

EXAMPLE 4
This example is designed for use with the MPLAB IDE v6.xx, the MPLAB SIM simulator
and the PIC18F452 device. It demonstrates the allocation of variables in access RAM.
For each value from 0 to 99, the program finds the square root of the value with the
fractional part truncated. It then squares this root to obtain the greatest perfect square
less than or equal to the original value.
• The square root function is implemented as a table in program memory. This has
several advantages. If the table were in data memory, it would need to be copied
from program memory to data memory at program initialization. Locating the table
in program memory also saves data memory space. Finally, the code associated
with calculating the square root at runtime may occupy more program memory
than a table when the domain of the function is small.
• Data located in access RAM does not require the BSR register to be loaded, thus
resulting in fewer instructions. The variables root and square are located in an
access RAM section named MY_ACS_DATA. The type qualifier near must be
used to ensure that MPLAB C18 knows bank selection is not required for these
objects.
This example can be built and linked in the MPLAB IDE v6.xx and used with the MPLAB
SIM simulator by following the steps in Example 1.
MPLAB C18, by default, assumes all statically allocated data objects, unless explicitly
specified with the near type qualifier, reside in banked (non-access) RAM. This default
behavior can be changed with the command-line option –Oa+. To make this change,
choose Project>Build Options>Project.
FIGURE 3-38:

DS51295E-page 46



Examples of Use
Select the tab labeled “MPLAB C18” and choose “Memory Model” from the drop-down
menu.
FIGURE 3-39:


MEMORY MODEL OPTION

DS51295E-page 47

Finally, select the small data model to tell MPLAB C18 that statically allocated data
objects without an explicit near or far qualifier are located in access RAM. See the
MPLAB® C18 C Compiler User’s Guide (DS51288) for details on access and banked
(non-access) RAM. Click OK.
FIGURE 3-40:

DS51295E-page 48

SMALL DATA MODEL OPTION


Examples of Use
#include <p18f452.h>

/* for 'PRODL' declaration and 'ACCESS' macro */

/*
* Locate the read-only table in program memory at address 0x1000.
* 'romdata' is used for data, and 'code' is used for instructions.
*/
#pragma romdata ROOT_TABLE = 0x1000
#define TABLE_SIZE 100
const rom unsigned char roots[TABLE_SIZE] =
{ 0, 1, 1, 1, 2, 2, 2, 2, 2, 3,
3, 3, 3, 3, 3, 3, 4, 4, 4, 4,
4, 4, 4, 4, 4, 5, 5, 5, 5, 5,
5, 5, 5, 5, 5, 5, 6, 6, 6, 6,
6, 6, 6, 6, 6, 6, 6, 6, 6, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 9, 9, 9, 9, 9, 9, 9, 9, 9,
9, 9, 9, 9, 9, 9, 9, 9, 9, 9 };

/*
* Data in access ram does not require banking.
* When compiled with -Oa, these pragmas and the near qualifier may
* be removed.
*/
#pragma udata access MY_ACS_DATA
near unsigned char root, square;
#pragma udata /* continue allocating static data in non-access ram */
/*
* Returns the truncated root of the value.
*/
unsigned char get_root (int val)
{
return roots[val];
}
void main (void)
{
static int val;
for (val = 0; val < TABLE_SIZE; val++)
{
/* 'square' holds the greatest perfect square less than or
* equal to 'val' */
square = get_root (val);
}

}
Note:


When compiling this example with static data in access RAM by default,
the udata pragmas surrounding the declarations of root and square may
be removed, as well as the near type qualifier.

DS51295E-page 49

3.6

EXAMPLE 5
This example is designed for use with the MPLAB ICD 2, the PICDEM 2 Plus demo
board, the MPLAB IDE v6.xx and the PIC18F452 device. It demonstrates the use of
interrupt service routines with MPLAB C18. It also provides an example of the use of
the MPLAB C18 peripheral libraries. For this program, the J6 jumper on the demo
board must be removed in order to disconnect the PORTB pins from the LEDs.
• This program generates the Piezo buzzer of the PICDEM 2 Plus demo board. The
user may disable the buzzer by pressing the S3 button. The buzzer may be
reactivated by pressing the button again.
• The S3 button is connected to the INT0 pin, which is associated with the INT0
external interrupt. This interrupt is a high priority interrupt, and so will always
trigger a branch to program memory address 0x8. Located at this address is the
interrupt service routine (high_ISR), which branches to the procedure that turns
the buzzer either off or on.
LVP=OFF, respectively). Finally, since this example exclusively uses the MPLAB
ICD 2, background debugging should always be enabled (DEBUG=ON). The
available configuration bit settings are listed in the PIC18 Configuration Settings
Addendum (DS51537).
• toggle_buzzer is declared as a high priority interrupt routine. This means the
WREG, BSR and STATUS registers will be saved and restored via their shadow
registers without explicit instructions upon interrupt routine entry and exit.
Additionally, upon return, the GIEH bit in the INTCON register will be set, which
was cleared when the interrupt was triggered. Refer to the PIC18FXX2 Data
Sheet (DS39564) for details on interrupt logic.
ICD 2 by following the steps in Example 1.
#include <p18f452.h> /* for the special function register declarations */
#include <portb.h>
/* for the RB0/INT0 interrupt */
*/
/*
* For high interrupts, control is transferred to address 0x8.
*/
void toggle_buzzer (void);
/* prototype needed for 'goto' below */
#pragma code HIGH_INTERRUPT_VECTOR = 0x8
void high_ISR (void)

DS51295E-page 50


Examples of Use
{
_asm
goto toggle_buzzer
_endasm
}
#pragma code

/* allow the linker to locate the remaining code */

/*
* If the buzzer is on, turn it off. If it is off, turn it on.
*/
#pragma interrupt toggle_buzzer
void toggle_buzzer (void)
{
CCP1CON = ~CCP1CON & 0x0F; /* turn the buzzer off or on */
INTCONbits.INT0IF = 0;
/* clear flag to avoid another interrupt */
}
void EnableHighInterrupts (void)
{
RCONbits.IPEN = 1;
/* enable interrupt priority levels */
INTCONbits.GIEH = 1;
/* enable all high priority interrupts */
}
void InitializeBuzzer (void)
{
T2CON = 0x05;
/*
TRISCbits.TRISC2 = 0;
/*
PR2 = 0x80;
/*
CCPR1L = 0x80;
/*
}
void SoundBuzzer (void)
{
CCP1CON = 0x0F;
while (1);
}

postscale 1:1, Timer2 ON, prescaler 4 */
configure the CCP1 module for the buzzer */
initialize the PWM period */
initialize the PWM duty cycle */

/* turn the buzzer on */
/* wait for the S3 button to be pressed */

void main (void)
{
EnableHighInterrupts ( );
InitializeBuzzer ( );
OpenRB0INT (PORTB_CHANGE_INT_ON & /* enable the RB0/INT0 interrupt */
PORTB_PULLUPS_ON &
/* configure the RB0 pin for input */
FALLING_EDGE_INT);
/* trigger interrupt upon S3
button depression */
SoundBuzzer ( );
}


DS51295E-page 51

3.7

EXAMPLE 6
This example is designed for use with the MPLAB ICD 2, the PICDEM 2 Plus demo
board, the MPLAB IDE v6.xx, and the PIC18F452 device. The key concepts of this
example are: creating large data objects, the use of interrupt service routines, and
reading from and writing to USART.
• This program will prompt the user (via HyperTerminal) to enter a digit between 0
and 9. Upon receiving a character from the USART, the program will then either
output a string from an array of data or if the character received is not between 0
and 9, output an error string.
• The USART receive is set up as a high-priority interrupt, which will trigger a
branch to the program memory address 0x08. At this address is located the
high-priority interrupt vector (rx_int), which branches to the function that services the USART receive interrupt (rx_handler). This function will determine
whether the key pressed is between 0 and 9 and output the correct string based
on the data received. In addition, it will light the LEDs to display the value of the
character received.
ICD 2 by following the steps in Example 1. A HyperTerminal properties file has been
provided for your convenience.
By default, MPLAB C18 assumes that an object will not cross a bank boundary. An
object that is larger than 256 bytes can be created, but the following steps are required
to create a multi-bank object:
1. The object must be allocated into its own section using the #pragma idata or
#pragma udata directive.
#pragma udata buffer_scn
static char buffer[0x180];
#pragma udata
2. A pointer to the object to use for access to that object must be created.
char * buf_ptr = &buffer[0];
...
// examples of use
buf_ptr[5] = 10;
if (buf_ptr[275] > 127)
...
3. A new region that spans multiple banks must be created in the linker script.
Linker script before modification:
DATABANK NAME=gpr2 START=0x200 END=0x2FF

Linker script after modification:
DATABANK NAME=big START=0x200 END=0x37F PROTECTED
4. The object’s section (created in step #1) must be assigned into the new region
(created in step #3). Add a SECTION directive to the linker script.
SECTION NAME=buffer_scn RAM=big

DS51295E-page 52


Examples of Use
#include <p18f452.h>
#include <usart.h>
*/
void rx_handler (void);
#define BUF_SIZE 25
/*
* Step #1 – The data is allocated into its own section.
*/
#pragma idata bigdata
char data[11][BUF_SIZE+1] = {
{ "String #0nr" },
{ "String #1nr" },
{ "String #2nr" },
{ "String #3nr" },
{ "String #4nr" },
{ "String #5nr" },
{ "String #6nr" },
{ "String #7nr" },
{ "String #8nr" },
{ "String #9nr" },
{ "Invalid key (0-9 only)nr" }
};
#pragma idata
#pragma code rx_interrupt = 0x8
void rx_int (void)
{
_asm goto rx_handler _endasm
}
#pragma code
#pragma interrupt rx_handler
void rx_handler (void)
{
unsigned char c;
/* Get the character received from the USART */
c = ReadUSART();
if (c >= '0' && c <= '9')
{
c -= '0';
/* Display value received on LEDs */
PORTB = c;


DS51295E-page 53

/*
* Step #2 – This example did not need an additional
* pointer to access the large memory because of the
* multi-dimension array.
*
* Display the string located at the array offset
* of the character received
*/
putsUSART (data[c]);
}
else
{
/*
* Step #2 – This example did not need an additional
* pointer to access the large memory because of the
* multi-dimension array.
*
* Invalid character received from USART.
* Display error string.
*/
putsUSART (data[10]);
/* Display value received on LEDs */
PORTB = c;
}
/* Clear the interrupt flag */
PIR1bits.RCIF = 0;
}
void main (void)
{
/* Configure all PORTB pins for output */
TRISB = 0;
/*
* Open the USART configured as
* 8N1, 2400 baud, in polled mode
*/
OpenUSART (USART_TX_INT_OFF &
USART_RX_INT_ON &
USART_ASYNCH_MODE &
USART_EIGHT_BIT &
USART_CONT_RX &
USART_BRGH_HIGH, 103);
/* Display a prompt to the USART */
putrsUSART (
(const far rom char *)"nrEnter a digit 0-9!nr");
/* Enable interrupt priority */
RCONbits.IPEN = 1;
/* Make receive interrupt high priority */
IPR1bits.RCIP = 1;
/* Enable all high priority interrupts */
/* Loop forever */
while (1)
;
}

DS51295E-page 54


Examples of Use
Linker Script:
//
//
//
//
//

This file was originally 18f452i.lkr as distributed with MPLAB C18.
Modified as follows:
- combine banks 4 and 5 into PROTECTED DATABANK "largebank"
- moved stack to gpr3
- Assign the "bigdata" SECTION into the new "largebank" region

LIBPATH .
FILES c018i.o
FILES clib.lib
FILES p18f452.lib
CODEPAGE
CODEPAGE
CODEPAGE
CODEPAGE
CODEPAGE
CODEPAGE
CODEPAGE

NAME=vectors
NAME=page
NAME=debug
NAME=idlocs
NAME=config
NAME=devid
NAME=eedata

START=0x0
START=0x2A
START=0x7DC0
START=0x200000
START=0x300000
START=0x3FFFFE
START=0xF00000

END=0x29
END=0x7DBF
END=0x7FFF
END=0x200007
END=0x30000D
END=0x3FFFFF
END=0xF000FF

PROTECTED

ACCESSBANK
DATABANK
DATABANK
DATABANK
DATABANK
// Step #3
// This is
DATABANK
DATABANK
ACCESSBANK

NAME=accessram START=0x0
END=0x7F
NAME=gpr0
START=0x80
END=0xFF
NAME=gpr1
START=0x100
END=0x1FF
NAME=gpr2
START=0x200
END=0x2FF
NAME=gpr3
START=0x300
END=0x3FF
– Create a new region in the linker script
the databank that will contain the large memory object
NAME=largebank START=0x400
END=0x5F3
PROTECTED
NAME=dbgspr
START=0x5F4
END=0x5FF
PROTECTED
NAME=accesssfr START=0xF80
END=0xFFF
PROTECTED

SECTION

NAME=CONFIG

PROTECTED
PROTECTED
PROTECTED
PROTECTED
PROTECTED

ROM=config

// Step #4 - Assign the large memory object's section into the new region
SECTION
NAME=bigdata
RAM=largebank
STACK SIZE=0x100 RAM=gpr3


DS51295E-page 55

3.8

EXAMPLE 7
This example is designed for use with the MPLAB ICD 2, the PIC18FXX20 64/80L
TQFP demo board, the MPLAB IDE v6.xx, and the PIC18F8720 device. The key concepts of this example are: the use of interrupt priority, reading from and writing to
EEDATA, and mixing interrupt driven and polling peripheral access.
• This program will rotate the LEDs of the PIC18FXX20 64/80L TQFP demo board,
which are attached to PORTD. When the lower left button is pushed, the direction
that the LEDs are rotating will reverse. The POT can be used to control the speed
of the rotating LEDs.
• Analog Channel 0 (AN0) for the ADC is attached to the POT. Peripheral access to
the ADC is done through polling in the main function. The ADC conversion results
in setting the current_ad_value variable, which is used in the TMR2 interrupt to
determine if the LEDs should be updated.
• The TMR2 interrupt is a low-priority interrupt, which will trigger a branch to the
program memory address 0x18. At this address is located the low-priority
interrupt vector (low_vector), which branches to the function that services the
TMR2 interrupt (tmr2). This function will determine whether it is time to update the
LEDs, and if it is, will rotate the LED to the next LED based on the direction.
• External interrupt 0 (RB0) is attached to the lower left button. This button when
pushed will trigger a high-priority interrupt, which will trigger a branch to the program memory address 0x08. At this address is located the high-priority interrupt
vector (high_vector), which branches to the function that services the external
interrupt (button). This function will change the direction that the LEDs are
rotating and write the updated direction variable to EEDATA.
• Master clear (MCLR) is attached to the upper right button.
• The first step that the main function will perform is to read the direction
variable from EEDATA.
ICD 2 by following the steps in Example 1.
The following steps are required to read EEDATA data from C code:
1. Ensure EEPGD is clear for EEDATA access
EECON1bits.EEPGD = 0;
2. Store the address to EEADR
EEADR = addr;
3. Trigger a read by setting the RD bit
EECON1bits.RD = 1;
4. Read the result from EEDATA register
my_variable = EEDATA;

DS51295E-page 56


Examples of Use
The following steps are required to write EEDATA data from C code:
1. Ensure EEPGD is clear for EEDATA access
EECON1bits.EEPGD = 0;
2. Ensure WREN is set to enable EEDATA writes
EECON1bits.WREN = 1;
3. Write address to EEADR
EEADR = addr;
4. Set EEDATA to the value to write
EEDATA = value;
5. Write 0x55 to EECON2
EECON2 = 0x55;
6. Write 0xAA to EECON2
EECON2 = 0xAA;
7. Initiate write cycle by setting the WR bit
EECON1bits.WR = 1;
8. Wait for the EEIF flag to be set
while (!PIR2bits.EEIF)
;
9. Clear the EEIF flag
PIR2bits.EEIF = 0;
Note:

Interrupts must be disabled during steps 5-7.

#include <p18cxxx.h>
#include <delays.h>
/* Set up the configuration bits */
#pragma config OSC = HS, OSCS = OFF
#pragma config PWRT = OFF
#pragma config BOR = OFF
#pragma config CCP2MUX = OFF
void tmr2 (void);
void button (void);
#pragma code high_vector_section=0x8
void
high_vector (void)
{
_asm
GOTO button
_endasm
}
#pragma code
#pragma code low_vector_section=0x18
void
low_vector (void)
{
_asm
GOTO tmr2
_endasm
}
#pragma code


DS51295E-page 57

volatile unsigned current_ad_value;
int count = 0;
volatile enum { DIR_LEFT = 0, DIR_RIGHT } direction;
#pragma interruptlow tmr2
void
tmr2 (void)
{
/* clear the timer interrupt flag */
PIR1bits.TMR2IF = 0;
/*
* if we have reached the repeat count,
* update the LEDs
*/
if (count++ < current_ad_value)
return;
else
count = 0;
/*
* Based on the direction, rotate the LEDs
*/
if (direction == DIR_LEFT)
{
_asm
RLNCF PORTD, 1, 0
_endasm
}
else
{
_asm
RRNCF PORTD, 1, 0
_endasm
}
}
#pragma interrupt button
void
button (void)
{
direction = !direction;
/*
* Store the new direction in EEDATA.
* Note that since we are already
* in the high priority interrupt, we do
* not need to explicitly enable/disable
* interrupts around the write cycle
*/
EECON1bits.EEPGD = 0; /* WRITE step #1 */
EECON1bits.WREN = 1;
/* WRITE step #2 */
EEADR = 0;
/* WRITE step #3 */
EEDATA = direction;
/* WRITE step #4 */
EECON2 = 0x55;
/* WRITE step #5 */
EECON2 = 0xaa;
/* WRITE step #6 */
EECON1bits.WR = 1;
/* WRITE step #7 */
while (!PIR2bits.EEIF) /* WRITE step #8 */
;
PIR2bits.EEIF = 0;
/* WRITE step #9 */

DS51295E-page 58


Examples of Use
/* clear the interrupt flag */
INTCONbits.INT0IF = 0;
}
void
main (void)
{
/*
* The first thing to do is to read
* the start direction from data EEPROM.
*/
EECON1bits.EEPGD = 0; /* READ step #1 */
EEADR = 0;
/* READ step #2 */
EECON1bits.RD = 1;
/* READ step #3 */
direction = EEDATA;
/* READ step #4 */
/*
* Make all bits on the Port D output
* bits for the LEDs
*/
TRISD = 0;
/* Make PORTA RA0 input, for the A/D converter */
TRISAbits.TRISA0 = 1;
/* PORTB RB0 input for the button */
TRISBbits.TRISB0 = 1;
/* Reset Port D. Set just one bit to on. */
PORTD = 1;
/* Enable interrupt priority */
RCONbits.IPEN = 1;
/* Clear the peripheral interrupt flags */
PIR1 = 0;
/* Enable the timer interrupt */
PIE1bits.TMR2IE = 1;
IPR1bits.TMR2IP = 0;
/*
* Set the button on RB0 to trigger an
* interrupt. It is always high priority
*/
INTCONbits.INT0IE = 1;
/*
*
*
*
*
*
*
*
*
*
*
*
*

Configure the ADC, most of this is the
default settings:
Fosc/32
AN0 Analog,
AN1-15 Digital Channel zero Interrupt disabled
Internal voltage references
An equivalent setup using the ADC
library would be:
OpenADC (ADC_FOSC_32 &
ADC_LEFT_JUST &
ADC_1ANA,
ADC_CH0 &


DS51295E-page 59

*
*
*
*/

ADC_INT_OFF &
ADC_VREFPLUS_VDD &
ADC_VREFMINUS_VSS );

/* FOSC/32 clock
ADCON2bits.ADCS0
ADCON2bits.ADCS1
ADCON2bits.ADCS2
ADCON2bits.ADCS2

select */
= 1;
= 1;
= 1;
= 1;

/* AN0-15, VREF */
ADCON1 = 0b00001110;
/* Enable interrupts */
INTCONbits.GIEL = 1;
/* Turn on the ADC */
ADCON0bits.ADON = 1;
/* Enable the timer */
T2CONbits.TMR2ON = 1;
/* Start the ADC conversion */
while (1)
{
/* Give the ADC time to get ready. */
Delay100TCYx (2);
/* start the ADC conversion */
ADCON0bits.GO = 1;
while (ADCON0bits.GO) ;
current_ad_value = ADRES;
}
}

DS51295E-page 60


GETTING STARTED
Glossary
A
Absolute Section
A section with a fixed address that cannot be changed by the linker.
Access Memory
Special general purpose registers on the PIC18 PICmicro microcontrollers that allow
access regardless of the setting of the Bank Select Register (BSR).
Address
The code that identifies where a piece of information is stored in memory.
Anonymous Structure
An unnamed object.
ANSI
American National Standards Institute
Assembler
A language tool that translates assembly source code into machine code.
Assembly
A symbolic language that describes the binary machine code in a readable form.
Assigned Section
A section that has been assigned to a target memory block in the linker command file.
Asynchronously
Multiple events that do not occur at the same time. This is generally used to refer to
interrupts that may occur at any time during processor execution.

B
Binary
The base two numbering system that uses the digits 0-1. The right-most digit counts
ones, the next counts multiples of 2, then 22 = 4, etc.

C
Central Processing Unit
The part of a device that is responsible for fetching the correct instruction for execution,
decoding that instruction and then executing that instruction. When necessary, it works
in conjunction with the Arithmetic Logic Unit (ALU) to complete the execution of the
instruction. It controls the program memory address bus, the data memory address bus
and accesses to the stack.
Compiler
A program that translates a source file written in a high-level language into machine
code.


DS51295E-page 61

Conditional Compilation
The act of compiling a program fragment only if a certain constant expression, specified
by a preprocessor directive, is true.
CPU
Central Processing Unit

E
endianness
The ordering of bytes in a multi-byte object.
Error File
A file containing the diagnostics generated by the MPLAB C18.
Extended Mode
In Extended mode, the compiler will utilize the extended instructions (i.e., ADDFSR,
ADDULNK, CALLW, MOVSF, MOVSS, PUSHL, SUBFSR and SUBULNK) and the indexed
with literal offset addressing.

F
Fatal Error
An error that will halt compilation immediately. No further messages will be produced.
Frame Pointer
A pointer that references the location on the stack that separates the stack-based
arguments from the stack-based local variables.
Free-standing
An implementation that accepts any strictly conforming program that does not use
complex types and in which the use of the features specified in the library clause
(ANSI ‘89 standard clause 7) are confined to the contents of the standard headers
<float.h>, <iso646.h>, <limits.h>, <stdarg.h>, <stdbool.h>,
<stddef.h> and <stdint.h>.

H
Hexadecimal
The base 16 numbering system that uses the digits 0-9 plus the letters A-F (or a-f).
The digits A-F represent decimal values of 10 to 15. The right-most digit counts ones,
the next counts multiples of 16, then 162 = 256, etc.
High-level Language
A language for writing programs that is further removed from the processor than
assembly.

I
ICD
In-Circuit Debugger
ICE
In-Circuit Emulator
IDE
Integrated Development Environment

DS51295E-page 62


Glossary
IEEE
Institute of Electrical and Electronics Engineers
Interrupt
A signal to the CPU that suspends the execution of a running application and transfers
control to an ISR so that the event may be processed. Upon completion of the ISR,
normal execution of the application resumes.
Interrupt Service Routine
A function that handles an interrupt.
ISO
International Organization for Standardization
ISR
Interrupt Service Routine

L
Latency
The time between when an event occurs and the response to it.
Librarian
A program that creates and manipulates libraries.
Library
A collection of relocatable object modules.
Linker
A program that combines object files and libraries to create executable code.
Little Endian
Within a given object, the least significant byte is stored at lower addresses.

M
Memory Model
A description that specifies the size of pointers that point to program memory.
Microcontroller
A highly integrated chip that contains a CPU, RAM, some form of ROM, I/O ports and
timers.
MPASM Assembler
Microchip Technology's relocatable macro assembler for PICmicro microcontroller
families.
MPLIB Object Librarian
Microchip Technology's librarian for PICmicro microcontroller families.
MPLINK Object Linker
Microchip Technology's linker for PICmicro microcontroller families.

N
Non-extended Mode
In Non-extended mode, the compiler will not utilize the extended instructions nor the
indexed with literal offset addressing.


DS51295E-page 63

O
Object File
A file containing object code. It may be immediately executable or it may require linking
with other object code files (e.g., libraries), to produce a complete executable program.
Object Code
The machine code generated by an assembler or compiler.
Octal
The base 8 number system that only uses the digits 0-7. The right-most digit counts
ones, the next digit counts multiples of 8, then 82 = 64, etc.

P
Pragma
A directive that has meaning to a specific compiler.

R
RAM
Random Access Memory
Random Access Memory
A memory device in which information can be accessed in any order.
Read Only Memory
Memory hardware that allows fast access to permanently stored data but prevents
addition to or modification of the data.
ROM
Read Only Memory
Recursive
Self-referential (e.g., a function that calls itself).
Reentrant
A function that may have multiple, simultaneously active instances. This may happen
due to either direct or indirect recursion or through execution during interrupt
processing.
Relocatable
An object whose address has not been assigned to a fixed memory location.
Run-time Model
Set of assumptions under which the compiler operates.

S
Section
A portion of an application located at a specific address of memory.
Section Attribute
A characteristic ascribed to a section (e.g., an access section).
Special Function Register
Registers that control I/O processor functions, I/O status, timers or other modes or
peripherals.

DS51295E-page 64


Glossary
Storage Class
Determines the lifetime of the memory associated with the identified object.
Storage Qualifier
Indicates special properties of the objects being declared (e.g., const).

V
Vector
The memory locations that an application will jump to when either a reset or interrupt
occurs.


DS51295E-page 65

NOTES:

DS51295E-page 66


GETTING STARTED
Index
Symbols

I

__EXTENDED18__ ................................................... 45
_mplink.exe ........................................................... 9

Include Path ............................................................. 25
Installing MPLAB C18 .............................................. 11
Internet Address......................................................... 5
Interrupt Priority........................................................ 56
Interrupt Service Routine ........................ 19, 50, 52, 63

A
Access RAM .......................................................19, 46
Add Files to Project .................................................. 27
Allocation of Variables
Access RAM ..................................................... 46
Program Memory .............................................. 39
Arrays, Large ........................................................... 52

B
Breakpoint .....................................................30, 32, 38
Build Options.......................................................24, 26
Build Project ........................................................29, 35

C
COD File Converter.................................................... 9
Compiler Setting ...................................................... 26
cpp18.exe................................................................ 9
Customer Change Notification Service ...................... 5
Customer Support ...................................................... 6

D
Debugger
MPLAB ICD 2 ................................................... 35
MPLAB SIM ...................................................... 30
Debugging...........................................................30, 35
Directory................................................................... 12
Directory Contents ..................................................... 8
Documentation ......................................................8, 14
Documentation Conventions ...................................... 3

E
EEDATA................................................................... 56
Read ................................................................. 56
Write ................................................................. 57
Electronic Documentation ........................................ 14
Examples ..................... 8, 14, 20, 39, 43, 46, 50, 52, 56
Executables ......................................................8, 9, 14
Extended Mode ......................................... 9, 19, 43, 45

H
Halt Program.......................................................33, 38
Header Files
Assembly .......................................................8, 14
Path .................................................................. 25
Standard C.....................................................8, 14
Hex............................................................................. 9


L
Language Tools ................................................... 9, 22
Flow .................................................................. 10
Large Code Model.................................................... 41
Libraries ............................................................... 8, 14
Library Path.............................................................. 25
Linker Script ............................................................. 55
Linker Scripts ............................................ 8, 14, 28, 35
Linker Settings ......................................................... 26
Linker-Script Path..................................................... 25
Listing Files .............................................................. 34
Little Endian ............................................................. 63

M
Map Files............................................................ 26, 34
MCC_INCLUDE ......................................................... 16
mcc18.exe................................................................ 9
mcc18-extended.exe ............................................ 9
mcc18-traditional.exe ...................................... 9
Memory Model ................................................... 40, 47
Microchip Web Site .................................................... 5
mp2cod.exe.............................................................. 9
mp2hex.exe.............................................................. 9
MPASM assembler .................................................... 8
mpasm.exe.............................................................. 10
MPLAB C18 Compiler Installation.............................. 9
MPLAB ICD 2........................................................... 35
MPLAB SIM Simulator ............................................. 30
mplib.exe................................................................ 9
MPLINK linker ............................................................ 9
mplink.exe.............................................................. 9

N
New Project.............................................................. 21
Non-extended Mode............................ 9, 19, 43, 44, 45

O
Output Window......................................................... 29

DS51295E-page 67

P
PATH Environment Variable .................................... 16
Paths ........................................................................ 25
Peripheral Libraries ............................................ 39, 50
PICDEM 2 Plus Demo.............................................. 39
Preprocessor .............................................................. 8
Program Device........................................................ 37
Project Paths ............................................................ 25
Project Settings ........................................................ 22
Project Tree.............................................................. 21

R
Readme File ......................................................... 4, 12
Recommended Reading............................................. 4
Run Program ...................................................... 32, 38

S
Select Device ........................................................... 21
Select Language Toolsuite....................................... 22
Small Code Model .................................................... 40
Small Data Model ..................................................... 48
Source Code .............................................................. 8
Processor-specific Libraries .............................. 14
Standard C Libraries ......................................... 14
Step Into ................................................................... 33
System Requirements ................................................ 7

T
Target Processor...................................................... 21
Toolsuite................................................................... 23

U
Uninstalling MPLAB C18 .......................................... 17
USART
Reading and Writing ......................................... 52

W
Watch Window ................................................... 31–33

DS51295E-page 68


Index
NOTES:


DS51295E-page 69

WORLDWIDE SALES AND SERVICE
AMERICAS

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03/01/05

DS51295E-page 70


C18 manual

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