Download Assembler/Linker/Librarian User's Guide

Sample Applications
13.3
SAMPLE APPLICATION 1 - TEMPLATES AND LINKER SCRIPTS
In the MPLAB X IDE or MPLAB IDE v8 installation, assembly source code templates
and generic linker script files are provided for most devices supported by the IDE. The
source code templates give you a starting point from which to begin coding. The
generic linker scripts are used automatically by the linker to simplify application
development. Or you may modify a linker script and then manually add it on the linker
command line or to the project.
This first general example will discuss templates and linker scripts.
13.3.1
Locating Templates and Linker Script Files
For MPLAB X IDE or MPLAB IDE v8 installed in the default location, source code
templates may be found at:
C:\Program Files\Microchip\MPASM Suite\Template
in the following subdirectories:
• Code - Contains absolute assembly code examples by device
• Object - Contains relocatable assembly code examples by device
The relocatable source code template 18F8722TMPO.ASM for the PIC18F8722 may
be found in the Object directory. This template provides oscillator setup, example
variable and EEPROM setup, reset and interrupt handling routines, and a section main
for application code.
For MPLAB X IDE installed in the default location, the generic linker script files may be
found at:
C:\Program Files\Microchip\MPASM Suite\LKR
The generic linker script file for the PIC18F8722 would be 18f8722_g.lkr. This file
defines initialization files, program code sections, GPR sections, and access memory
sections. These definitions are grouped based on debugger or programmer usage, and
regular or extended memory usage.
Program memory sections specified by the template code and linker script are
compared below.
TABLE 13-4: PROGRAM MEMORY MAP - PIC18F8722
Program
Memory
Address
0x0000
0x0007
Linker Script Section
(Not debug or extended)
page - ROM code space
Template Source Code Section
RESET_VECTOR - Reset vector
0x0008
0x0017
HI_INT_VECTOR - High priority interrupt
vector
0x0018
LOW_INT_VECTOR - Low priority
interrupt vector
0x0019
0x01FFFF
High_Int - High priority interrupt handler
Low_Int - Low priority interrupt handler
Main - Main application code
0x200000
0x200007
idlocs - ID locations
0x300000
0x30000D
config - Configuration bits
0x3FFFFE
0x3FFFFF
devid - Device ID
0xF00000
0xF003FF
eedata - EEPROM data
 1994-2013 Microchip Technology Inc.
CONFIG - Configuration settings
DATA_EEPROM - Data EEPROM
DS33014L-page 261