dsPIC™
LANGUAGE TOOLS
GETTING STARTED
2003 Microchip Technology Inc.
DS70094B
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 intended through suggestion only
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
No representation or warranty is given and no liability is
assumed by Microchip Technology Incorporated with respect
to the accuracy or use of such information, or infringement of
patents or other intellectual property rights arising from such
use or otherwise. Use of Microchip’s products as critical
components in life support systems is not authorized except
with express written approval by Microchip. No licenses are
conveyed, implicitly or otherwise, under any intellectual
property rights.
Trademarks
The Microchip name and logo, the Microchip logo, Accuron,
dsPIC, KEELOQ, MPLAB, PIC, PICmicro, PICSTART,
PRO MATE and PowerSmart are registered trademarks of
Microchip Technology Incorporated in the U.S.A. and other
countries.
AmpLab, FilterLab, microID, MXDEV, MXLAB, PICMASTER,
SEEVAL, SmartShunt and The Embedded Control Solutions
Company are registered trademarks of Microchip Technology
Incorporated in the U.S.A.
Application Maestro, dsPICDEM, dsPICDEM.net,
dsPICworks, ECAN, ECONOMONITOR, FanSense,
FlexROM, fuzzyLAB, In-Circuit Serial Programming, ICSP,
ICEPIC, microPort, Migratable Memory, MPASM, MPLIB,
MPLINK, MPSIM, PICkit, PICDEM, PICDEM.net, PICtail,
PowerCal, PowerInfo, PowerMate, PowerTool, rfLAB, rfPIC,
Select Mode, SmartSensor, SmartTel and Total Endurance
are trademarks of Microchip Technology Incorporated in the
U.S.A. and other countries.
Serialized Quick Turn Programming (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.
© 2003, 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, non-volatile memory and analog
products. In addition, Microchip’s quality system for the design and
manufacture of development systems is ISO 9001:2000 certified.
DS70094B-page ii
2003 Microchip Technology Inc.
dsPIC™ LANGUAGE TOOLS
GETTING STARTED
Table of Contents
Chapter 1. Installation and Overview
1.1 Introduction ..................................................................................................... 1
1.2 Installing MPLAB ASM30, MPLAB LINK30 and Language Tool Utilities ....... 1
1.3 Installing MPLAB C30 .................................................................................... 1
1.4 Uninstalling MPLAB C30 ................................................................................ 1
1.5 Overview ........................................................................................................ 2
1.6 Tutorials .......................................................................................................... 2
Chapter 2. Tutorial 1 - Creating A Project
2.1 Introduction ..................................................................................................... 3
2.2 Creating a File ................................................................................................ 3
2.3 Using the Project Wizard ................................................................................ 4
2.4 Building The Project ..................................................................................... 10
2.5 Debugging with the MPLAB SIM30 Simulator .............................................. 16
2.6 Exploring Further .......................................................................................... 23
Chapter 3. Tutorial 2 - Real-Time Interrupt
3.1 Introduction ................................................................................................... 25
3.2 Using Template Files .................................................................................... 25
3.3 Using the Template in a New Project ........................................................... 30
3.4 Debugging with the MPLAB SIM30 Simulator .............................................. 36
3.5 Exploring Further .......................................................................................... 40
Chapter 4. Tutorial 3 - Mixed C and Assembly Files
4.1 Introduction ................................................................................................... 41
4.2 Getting Project Source Files ......................................................................... 41
4.3 Creating and Building the Project ................................................................. 44
4.4 Examining the Program ................................................................................ 45
4.5 Exploring Further .......................................................................................... 50
4.6 Where to Go from Here ................................................................................ 50
Index ............................................................................................................................. 51
Worldwide Sales and Service .................................................................................... 52
2003 Microchip Technology Inc.
DS70094B-page iii
dsPIC™ Language Tools Getting Started
NOTES:
DS70094B-page iv
2003 Microchip Technology Inc.
dsPIC™ LANGUAGE TOOLS
GETTING STARTED
Chapter 1. Installation and Overview
1.1
INTRODUCTION
This document is intended to help use dsPIC30F software tools by providing a
step-by-step guide using of MPLAB® C30 with the MPLAB Integrated Development
Environment (IDE) v6.30 or later. MPLAB IDE should already be installed on the PC.
MPLAB IDE is provided on CD-ROM and is available from www.microchip.com at no
charge. The project manager for MPLAB IDE and the dsPIC30F simulator are both
components of MPLAB IDE and, along with the built-in debugger, will be used
extensively in this guide.
1.2
INSTALLING MPLAB ASM30, MPLAB LINK30 AND LANGUAGE TOOL
UTILITIES
MPLAB ASM30 and MPLAB LINK30 are provided free with MPLAB IDE. They are also
included in the MPLAB C30 compiler installation. To ensure compatibility between all
dsPIC30F tools, the versions of these tools provided with MPLAB C30 compiler should
be used.
1.3
INSTALLING MPLAB C30
• When installing MPLAB C30 compiler as an update to a previous version, it may
overwrite existing files on the PC. A backup should be made to retain files which
may have been modified.
• Insert the CD-ROM into the PC and execute the installation MPLAB C30 vX.XX
(where X.XX is the curent version number) file. A series of dialogs will step
through the installation process. The installation may take a few minutes as it
searches for MPLAB IDE and other related files on the PC.
• To follow the examples in this guide, make sure that the check box for
EXAMPLES is checked.
1.4
UNINSTALLING MPLAB C30
To uninstall MPLAB C30, open the folder where the compiler is installed and
double-click on UNWISE.EXE.
Note:
2003 Microchip Technology Inc.
When uninstalling an upgraded version of MPLAB C30, the entire
installation will be removed. If files have been added to directories after the
previous installation, these will not be removed.
DS70094B-page 1
dsPIC™ Language Tools Getting Started
1.5
OVERVIEW
The following tutorials are intended to help an engineer familiar with the
C programming language and embedded systems concepts get started using the
MPLAB C30 compiler with MPLAB Integrated Development Environment (IDE). This
document shows how to create and build projects, how to write code using features of
dsPIC30F devices and how to verify and debug code written with MPLAB C30.
These tutorials assume that the MPLAB C30 compiler and MPLAB IDE v6.30 (or later)
are installed. Please refer to the dsPIC literature, such as the dsPIC30F Enhanced
Flash 16-Bit Digital Signal Controller General Purpose and Sensor Families Data Sheet
(DS70083) and dsPIC30F Programmer’s Reference Manual (DS70030) for information
regarding processor-specific items such as the special function registers, instruction
set and interrupt logic.
1.6
TUTORIALS
Tutorials presented in these chapters for using the MPLAB C30 compiler include:
• Chapter 2 which demonstrates how to:
- set up and build a project
- run, step and set breakpoints in the example code
- debug the code.
• Chapter 3 which demonstrates how to:
- use templates to create a source file
- use a real-time interrupt in C
• Chapter 4 which demonstrates how to:
- use MPLAB C30 compiler with an assembly language DSP routine
- pass parameters to and from an assembly language module
DS70094B-page 2
2003 Microchip Technology Inc.
dsPIC™ LANGUAGE TOOLS
GETTING STARTED
Chapter 2. Tutorial 1 - Creating A Project
2.1
INTRODUCTION
The simple source code in this tutorial is designed for an MPLAB IDE v6.XX project
which will be created next. It will use the MPLAB SIM30 simulator and the PIC30F6014
device. The tutorial assumes that the directory c:\pic30_tools is the MPLAB C30
compiler installation directory.
2.2
CREATING A FILE
Start MPLAB IDE v6.30 (or later) and select File>New to bring up a new empty source
file. The source code that should be typed in (or copy and pasted if viewing this
electronically) to this new source file window is shown in Example 2-1.
EXAMPLE 2-1:
#include
MYFILE.C
"p30f6014.h"
// for TRISB and PORTB declarations
int counter;
int main (void)
{
counter = 1;
TRISB = 0;
while(1)
{
PORTB = counter;
counter++;
}
return 0;
}
// configure PORTB for output
// do forever
// send value of ‘counter’ out PORTB
TRISB and PORTB are special function registers on the PIC30F6014 device. PORTB is
a set of general purpose input/output pins. TRISB bits configure the PORTB pins as
inputs (1) or outputs (0).
Use File>Save As... to save this file with the file name MyFile.c in the \examples
folder under the installation folder (usually c:\pic30_tools\examples).
2003 Microchip Technology Inc.
DS70094B-page 3
dsPIC™ Language Tools Getting Started
2.3
USING THE PROJECT WIZARD
Select Project>Project Wizard to create a new project. This is the Welcome page. Click
Next> to continue.
FIGURE 2-1:
PROJECT WIZARD - START
At Step One, select a dsPIC30F device. Use the pull-down menu to select the
dsPIC30F6014. Press Next> to continue to the next dialog.
FIGURE 2-2:
PROJECT WIZARD - SELECT DEVICE
At Step Two choose “Microchip C30 Toolsuite” as the Active Toolsuite. Then make
sure that MPLAB knows where the C30 tools are located. If the MPLAB C30 compiler
has been installed, these will have already been set up. Verify that the compiler,
assembler and linker are shown in the Location of Selected Tool field. Figure 2-3,
Figure 2-4 and Figure 2-5 show the default locations of MPLAB C30, MPLAB ASM30
and MPLINK30, respectively.
DS70094B-page 4
2003 Microchip Technology Inc.
Tutorial 1 - Creating A Project
FIGURE 2-3:
PROJECT WIZARD - TOOLSUITE: ASM30
FIGURE 2-4:
PROJECT WIZARD - TOOLSUITE: C30
FIGURE 2-5:
PROJECT WIZARD - TOOLSUITE: MPLINK30
2003 Microchip Technology Inc.
DS70094B-page 5
dsPIC™ Language Tools Getting Started
Press the Next> button to advance to the next wizard dialog.
At Step Three select the name of the project. Type in MyProject and then use the
Browse button to go the \examples folder in the installation folder of MPLAB C30.
FIGURE 2-6:
PROJECT WIZARD - PROJECT NAME AND DIRECTORY
Press Next> to go to the next dialog in the Project Wizard.
At Step Four, files to be added to the project can be set up. First, select the source file
created earlier, MyFile.c in the \examples folder under the installation folder.
FIGURE 2-7:
DS70094B-page 6
PROJECT WIZARD - ADD C SOURCE FILE0
2003 Microchip Technology Inc.
Tutorial 1 - Creating A Project
Place the cursor over MyFile.c in the left window and click to highlight. Press ADD>>
to add it to the list of files to be used for this project (in the right window).
FIGURE 2-8:
PROJECT WIZARD - ADDED C SOURCE FILE
In addition to the source file, a linker script is required to tell the linker about the memory
organization of the dsPIC30F6014. Linker scripts are located in the \support\gld
directory in the dsPIC30F tools installation directory.
FIGURE 2-9:
2003 Microchip Technology Inc.
PROJECT WIZARD - ADD LINKER SCRIPT
DS70094B-page 7
dsPIC™ Language Tools Getting Started
Scroll down to the p30f6014.gld file, click on it to highlight, and press ADD>> to add
the file to the right window for the project.
FIGURE 2-10:
PROJECT WIZARD - ADDED ALL FILES
Select Next> to add these files to the project.
At the summary screen review the Project Parameters to verify that the device, tool
suite and project file location are correct.
FIGURE 2-11:
DS70094B-page 8
PROJECT WIZARD - END
2003 Microchip Technology Inc.
Tutorial 1 - Creating A Project
The wizard will create the new project and workspace. Press Finish, and locate the
project window on the MPLAB IDE workspace. The file name of the workspace should
appear in the top title bar of the project window, MyProject.mcw, with the file name
as the top “node” in the project, MyProject.mcp.
The project window should now look like this:
FIGURE 2-12:
Note:
2003 Microchip Technology Inc.
PROJECT WINDOW
If an error was made, highlight a file name and press the Delete key or use
the right mouse menu to delete a file. Place the cursor over Source Files or
Linker Scripts and use the right mouse menu to add the proper files to the
project.
DS70094B-page 9
dsPIC™ Language Tools Getting Started
2.4
BUILDING THE PROJECT
The dsPIC30F tools are almost ready to be invoked to build the project. First, double
check that the system is correctly set up for the dsPIC30F tools directories. This should
be automatic, but select Project>Build Options and click on “project” to display the Build
Options dialog for the entire project. Look at the General tab to see that the Include
Path and Library path are pointing to the appropriate folders under the dsPIC30F tools
installation directory.
FIGURE 2-13:
DS70094B-page 10
BUILD OPTIONS DIALOG
2003 Microchip Technology Inc.
Tutorial 1 - Creating A Project
2.4.1
Verify Compiler and Linker Settings
The various command-line options that are passed to the compiler and linker can be
set on the MPLAB C30 and MPLINK LINK30 tabs, respectively, in the Build Options
dialog. There are three dialogs of options for MPLAB C30:
• General
• Memory Model
• Optimizations
These are selected in the Categories pull-down. For this example accept the default
command-line options for MPLAB C30.
FIGURE 2-14:
2003 Microchip Technology Inc.
COMPILER GENERAL BUILD OPTIONS
DS70094B-page 11
dsPIC™ Language Tools Getting Started
DS70094B-page 12
FIGURE 2-15:
COMPILER MEMORY MODEL BUILD OPTIONS
FIGURE 2-16:
COMPILER OPTIMIZATION BUILD OPTIONS
2003 Microchip Technology Inc.
Tutorial 1 - Creating A Project
MPLAB LINK30 needs to have a heap setting added to its Build Options in order to run
Tutorial 3 in this guide. Enter 512 as the Heap size in the following dialog:
FIGURE 2-17:
LINKER BUILD OPTIONS - GENERAL
The build options for the linker have two other dialogs besides this “General” screen
that are not shown – Diagnostics and Symbols & Output. These dialogs do not need to
be changed from their default values.
Finally, look at the MPLAB ASM30 build options. They should look like this:
FIGURE 2-18:
ASSEMBLER BUILD OPTIONS - GENERAL
MPLAB ASM30 also has another dialog besides “General”, called Diagnostics (not
shown), no changes to it are required.
2003 Microchip Technology Inc.
DS70094B-page 13
dsPIC™ Language Tools Getting Started
2.4.2
Build the Project
Select Project>Build All to compile, assemble and link the project. If there are any error
or warning messages, they will appear in the output window.
FIGURE 2-19:
BUILD ALL
For this tutorial, the output window should display no errors and should show a
message stating the project “BUILD SUCCEEDED.” If there were any errors, check to
see that the content of the source file matches the text of myfile.c displayed in
Example 2-1.
FIGURE 2-20:
DS70094B-page 14
BUILD OUTPUT WINDOW
2003 Microchip Technology Inc.
Tutorial 1 - Creating A Project
2.4.3
Build Errors
If errors were reported after building the project, double click on the line with the error
message to go directly to the source code line that caused the error. If the example was
typed in, the most common errors are misspellings, missing semicolons or unmatched
braces. In the following screen, a typo was made. In this example, the letter “i” was
accidentally omitted in the “int” declaration of main(). The error message will appear
in the output window.
FIGURE 2-21:
BUILD ERROR
After double clicking on the third line in the output window above, the desktop looks like
this:
FIGURE 2-22:
DOUBLE CLICK TO GO TO SOURCE
Note that the offending typo “nt” is in black text rather than blue – a good indication
that something is wrong, since key words are shown in blue color fonts. Typing an “i”
to make the “nt” the proper key word “int,” results in the text turning blue. Selecting
Project>Project Build All again produces a successful build.
2003 Microchip Technology Inc.
DS70094B-page 15
dsPIC™ Language Tools Getting Started
2.5
DEBUGGING WITH THE MPLAB SIM30 SIMULATOR
With the MPLAB SIM30 Simulator, breakpoints can be set in the source code and the
value of variables can be observed with a watch window. First, make sure that the
MPLAB SIM30 Simulator is set as the debugging tool by selecting Debugger>Select
Tool>MPLAB SIM30.
FIGURE 2-23:
SELECT SIM30
Open the source file by double-clicking on its name in the project tree. In the source
file, place the cursor over the line PORTB = counter;, click the right mouse button
and select “Set Breakpoint”.
FIGURE 2-24:
DS70094B-page 16
SET BREAKPOINT
2003 Microchip Technology Inc.
Tutorial 1 - Creating A Project
The red stop sign symbol in the margin along the left side of the source window
indicates that the breakpoint has been set and is enabled.
FIGURE 2-25:
BREAKPOINT IN SOURCE WINDOW
To open a Watch window on the variable counter, select View>Watch.
FIGURE 2-26:
SELECT WATCH WINDOW
Select counter from the pull down expandable menu next to Add Symbol, and select
Add Symbol.
FIGURE 2-27:
Note:
2003 Microchip Technology Inc.
ADD WATCH VARIABLE
There are three ways to enter Watch variables. In the method described
above a variable can be picked from a list. The symbol’s name can also
be typed directly in the Symbol Name column in the Watch window.
Alternatively, the variable’s name can be highlighted in the source text and
dragged to the Watch window.
DS70094B-page 17
dsPIC™ Language Tools Getting Started
Press 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 left margin of the source window points to the next statement to be
executed. The watch window should show counter with a value of ‘1’. The value of
‘1’ will be shown in red, indicating that this variable has changed.
FIGURE 2-28:
RUN TO BREAKPOINT
Press Run again to continue the program. Execution will continue in the while loop
until it halts again at the line with the breakpoint. The Watch window should show
counter with a value of ‘2’.
FIGURE 2-29:
DS70094B-page 18
WATCH WINDOW INSPECTION
2003 Microchip Technology Inc.
Tutorial 1 - Creating A Project
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 margin of the source window
moves to the next statement to be executed.
Place the cursor on the line with the breakpoint, and use the right mouse button menu
to select “Remove Breakpoint”. Now press the Run button. The “Running...” message
should appear on the lower left of the Status bar, and next to it, a moving bar will
indicate that the program is running. The Step icon to the right of the Run Icon will be
grayed out. If the Debugger menu is pulled down, the Step options will also be grayed
out. While in the Run mode, these operations are disabled.
When the program is running, it can be interrupted by pressing Halt on the toolbar:
Press this button now. Note that the step icons are no longer grayed out.
Note:
2003 Microchip Technology Inc.
There are two basic modes while debugging: Halt or Run. Most debugging
operations are done in Halt mode. In Run mode, most debug functions are
not operational. Registers cannot be inspected, changed or a project
rebuilt. Functions that try to access the memory or internal registers of the
running target will not be available in Run mode.
DS70094B-page 19
dsPIC™ Language Tools Getting Started
2.5.1
Map Files
A map file can be generated by setting the appropriate switch in Project>Build Options.
Go to the MPLAB LINK30 tab and select the Diagnostics dialog.
FIGURE 2-30:
GENERATE MAP FILE
Click on Generate map file, then click on OK to save the settings and close the dialog.
Then rebuild the project.
The map file (MyProject.map) is present in the project directory and may be opened
by selecting File>Open, and then browsing to the project directory. Select Files of Type
“All files(*.)” in order to see the map file. This file provides additional information that
may be useful in debugging, such as details of memory allocation. For example, this
excerpt from the MyProject.map file shows the program and data memory area
usage after MyProject.C was compiled:
EXAMPLE 2-2:
MAP FILE EXCERPT
Program Memory Usage
section
------.reset
.ivt
.aivt
.text
.dinit
address
------0
0x4
0x84
0x100
0x1a0
length (PC units)
----------------0x4
0x7c
0x7c
0xa0
0x8
Total program memory used (bytes):
length (bytes)
(dec)
-------------------0x6
(6)
0xba
(186)
0xba
(186)
0xf0
(240)
0xc
(12)
0x276
(630)
Data Memory Usage
section
------.bss
address
------0x800
alignment gaps
-------------0
Total data memory used (bytes):
DS70094B-page 20
total length
(dec)
------------------0x4
(4)
0x4
(4)
2003 Microchip Technology Inc.
Tutorial 1 - Creating A Project
2.5.2
Debugging at Assembly Code Level
So far all debugging has been done from the C source file, using functions and
variables as defined in the C code. For embedded systems programming, it may be
necessary to dig down deeper into the assembly code level. MPLAB IDE provides tools
to do both, and shows the correlation between the C code and the generated machine
code.
Select the MPLAB IDE View>Disassembly Listing window to see the source code
interspersed with the generated machine and assembly code. This is useful when
debugging mixed C and assembly code, and when it is necessary to see the machine
code generated from the C source code.
FIGURE 2-31:
DISASSEMBLY WINDOW
The C source code is shown with the line number from the source code file shown on
the left column. The generated machine HEX code and the corresponding disassembled instructions are shown with the address in the left column. For the machine code
instructions the left column is the address of the instruction in program memory, followed by the hexadecimal bytes for the instruction and then the dsPIC30F disassembled instruction.
Select View>Program Memory window to see only the machine and assembly code in
program memory.
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DS70094B-page 21
dsPIC™ Language Tools Getting Started
FIGURE 2-32:
PROGRAM MEMORY WINDOW - SYMBOLIC
By selecting the various tabs at the bottom of the Program Memory window, the code
can be viewed with or without symbolic labels, as a raw HEX dump, as mixed PSV code
and data, or just as PSV data.
Note:
See the dsPIC® device data sheet for more information about PSV data.
Breakpoints can be set, single-stepped, and all debug functions perform in any of the
Source code, Disassembly and Program Memory windows.
Make sure the program is halted by pressing the Halt button. In the Program Memory
window click on the Symbolic tab at the bottom to view the code tagged with symbols.
Scroll down and click on the line named main, which corresponds to the main()
function in the C file. Use the right mouse button to set a breakpoint on main. Press
the Reset icon (or select to Debugger>Reset and select Processor Reset).
Now press Run. The program should halt at the breakpoint set at main.
DS70094B-page 22
2003 Microchip Technology Inc.
Tutorial 1 - Creating A Project
FIGURE 2-33:
2.6
BREAKPOINT IN PROGRAM MEMORY
EXPLORING FURTHER
Go back and look at the Source file window and the Disassembly window. The breakpoint should be seen in all three windows. The step function can now be used in any
window to single step through C source lines or to single step through the machine
code.
Go ahead and experiment with this example program. Things to explore include:
Changing the value of counter by clicking on its value in the Watch window and typing
in a new number.
Assigning counter an initial value of one in its definition. Inspect the source code to
see where counter is loaded with this value.
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DS70094B-page 23
dsPIC™ Language Tools Getting Started
NOTES:
DS70094B-page 24
2003 Microchip Technology Inc.
dsPIC™ LANGUAGE TOOLS
GETTING STARTED
Chapter 3. Tutorial 2 - Real-Time Interrupt
3.1
INTRODUCTION
This next tutorial demonstrates real-time interrupt code implemented using the basic
“template” file that comes with MPLAB® IDE software. Timer 1 on the dsPIC30F6104
will be used to generate a recurring interrupt to measure one-second intervals.
3.2
USING TEMPLATE FILES
Template files are source code files that can serve as a structure to build an application.
They make it easy to start a project for an application since the C constructs and
formats are provided in a simple file where details of an application can be added. The
templates have example C statements for many common features of C30 source code,
including variables and constants, processor-specific include files, interrupt vectors
and associated interrupt code, plus areas to insert application code.
The template has comments to help identify key constructs. In many cases macros are
defined to make some things easier. In the simplest form, here is a “stripped-down”
template without these comments and macros so its basic structure can be seen:
EXAMPLE 3-1:
ELEMENTS OF A TEMPLATE FILE
#include "p30F6014.h"
/* proc specific header */
#define CONSTANT1 10
/* sample constant definition */
int array1[CONSTANT1] __attribute__((__section__(".xbss"), __aligned__(32)));
/* array with dsPIC30F attributes */
int array5[CONSTANT2];
/* simple array */
int variable1 __attribute__((__section__(".xbss")));
/* variable with attributes */
int variable3;
/* simple variable */
int main ( void )
{
/* Application code goes here */
}
/* start of main application code */
void __attribute__((__interrupt__(__save__(variable1,variable2)))) _INT0Interrupt(void)
/* interrupt routine code */
{
/* Interrupt Service Routine code goes here */
}
This template code starts out with the #include statement to include the header file
that has the processor-specific special function register definitions for this particular
processor (dsPIC30F6014). Following this is a simple constant definition that can be
modified and copied to make a list of constants for the application.
Two array definitions follow to show how to define an array with various attributes,
specifying its section in memory, and how it is aligned in the memory architecture of the
dsPIC device. The second array definition, array5, is a simple array.
Like arrays, variables can be assigned with attributes (variable1), or with no
attributes (variable3).
A code fragment for main() follows. This is where code for the application can be
placed. Following main() is the code framework for an interrupt.
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DS70094B-page 25
dsPIC™ Language Tools Getting Started
Actual applications may use different interrupts, different attributes, and will be more
complicated than this, but this template provides a simple place to start. Along with the
appropriate linker file, the unmodified template can be added to a new project, and the
project will build with no errors.
Templates are stored in a folder with the dsPIC tools installation directory named
\support\templates, and are provided for both assembler and compiler source
files in the corresponding \asm and \c folders.
Here is the full source code for the C template file for the dsPIC30F6014:
EXAMPLE 3-2:
TEMP_6014.C TEMPLATE FILE
/***********************************************************************
* This file is a basic template for creating C code for a dsPIC30F
*
* device. Copy this file into your project directory and modify or
*
* add to it as needed.
*
* Add the suitable linker script (e.g., p30f6014.gld) to the project. *
*
*
* If interrupts are not used, all code presented for that interrupt
*
* can be removed or commented out with C-style comment declarations. *
*
*
* For additional information about dsPIC architecture and language
*
* tools, refer to the following documents:
*
*
*
* MPLAB C30 Compiler User's Guide
: C30.pdf
*
* MPLAB C30 Compiler Reference Guide
: R30.pdf
*
* dsPIC 30F Assembler, Linker and Utilities User's Guide : ALU.pdf
*
* dsPIC 30F 16-bit MCU Family Reference Manual
: DS70046
*
* dsPIC 30F Sensor and General Purpose Family Data Sheet : DS70083
*
* dsPIC 30F Programmer's Reference Manual
: DS70030
*
*
*
* Template file has been compiled with MPLAB C30 V 1.0.
*
*
*
***********************************************************************
*
*
*
Author:
*
*
Company:
*
*
Filename:
temp_6014.c
*
*
Date:
06/14/2002
*
*
File Version:
1.00
*
*
Other Files Required: p30F6014.gld, libpic30.a
*
*
Tools Used: MPLAB GL -> 6.00
*
*
Compiler -> 1.00
*
*
Assembler -> 1.00
*
*
Linker
-> 1.00
*
*
*
*
Devices Supported:
*
*
dsPIC30F2011
*
*
dsPIC30F3012
*
*
dsPIC30F2012
*
*
dsPIC30F3013
*
*
dsPIC30F3014
*
*
dsPIC30F5011
*
*
dsPIC30F6011
*
*
dsPIC30F6012
*
*
dsPIC30F5013
*
*
dsPIC30F6013
*
*
dsPIC30F6014
*
*
*
***********************************************************************
DS70094B-page 26
2003 Microchip Technology Inc.
Tutorial 2 - Real-Time Interrupt
EXAMPLE 3-2:
TEMP_6014.C TEMPLATE FILE (CONTINUED)
***********************************************************************
*
*
* Other Comments:
*
*
*
* 1) C attributes, designated by the __attribute__ keyword, provide a *
*
means to specify various characteristics of a variable or
*
*
function, such as where a particular variable should be placed
*
*
in memory, whether the variable should be aligned to a certain
*
*
address boundary, whether a function is an Interrupt Service
*
*
Routine (ISR), etc. If no special characteristics need to be
*
*
specified for a variable or function, then attributes are not
*
*
required. For more information about attributes, refer to the
*
*
C30 User's Guide.
*
*
*
* 2) The __section__(".xbss") and __section__(".ybss") attributes are *
*
used to place a variable in X data space and Y data space,
*
*
respectively. Variables accessed by dual-source DSP instructions *
*
must be defined using these attributes.
*
*
*
* 3) The aligned(k) attribute, used in variable definitions, is used *
*
to align a variable to the nearest higher 'k'-byte address
*
*
boundary. 'k' must be substituted with a suitable constant
*
*
number when the ModBuf_X(k) or ModBuf_Y(k) macro is invoked.
*
*
In most cases, variables are aligned either to avoid potential
*
*
misaligned memory accesses, or to configure a modulo buffer.
*
*
*
* 4) The __interrupt__ attribute is used to qualify a function as an *
*
interrupt service routine. An interrupt routine can be further
*
*
configured to save certain variables on the stack, using the
*
*
__save__(var-list) directive.
*
*
*
* 5) The __shadow__ attribute is used to set up any function to
*
*
perform a fast context save using shadow registers.
*
*
*
* 6) Note the use of double-underscores (__) at the start and end of *
*
all the keywords mentioned above.
*
*
*
**********************************************************************/
/* Include the appropriate header (.h) file, depending on device used */
/* Replace the path shown here with the header path in your system
*/
/* Example (for dsPIC30F5013): #include "Your_path\p30F5013.h"
*/
/* Alternatively, the header file may be inserted from the Project
/* window in the MPLAB IDE
*/
*/
#include "p30F6014.h"
/* Define constants here
*/
#define CONSTANT1 10
#define CONSTANT2 20
/* Define macros to simplify attribute declarations */
#define ModBuf_X(k) __attribute__((__section__(".xbss"), __aligned__(k)))
#define ModBuf_Y(k) __attribute__((__section__(".ybss"), __aligned__(k)))
2003 Microchip Technology Inc.
DS70094B-page 27
dsPIC™ Language Tools Getting Started
EXAMPLE 3-2:
TEMP_6014.C TEMPLATE FILE (CONTINUED)
/************* START OF GLOBAL DEFINITIONS **********/
/* Define arrays: array1[], array2[], etc.
/* with attributes, as given below
*/
*/
/* either using the entire attribute
*/
int array1[CONSTANT1] __attribute__((__section__(".xbss"), __aligned__(32)));
int array2[CONSTANT1] __attribute__((__section__(".ybss"), __aligned__(32)));
/* or using macros defined above
int array3[CONSTANT1] ModBuf_X(32);
int array4[CONSTANT1] ModBuf_Y(32);
*/
/* Define arrays without attributes
*/
int array5[CONSTANT2];
/* array5 is NOT an aligned buffer */
/* ------------------------------------------------ */
/* Define global variables with attributes
*/
int variable1 __attribute__((__section__(".xbss")));
int variable2 __attribute__((__section__(".ybss")));
/* Define global variables without attributes
*/
int variable3;
/************** END OF GLOBAL DEFINITIONS ***********/
/************* START OF MAIN FUNCTION ***************/
int main ( void )
{
/* Code goes here
*/
}
DS70094B-page 28
2003 Microchip Technology Inc.
Tutorial 2 - Real-Time Interrupt
EXAMPLE 3-2:
TEMP_6014.C TEMPLATE FILE (CONTINUED)
/****** START OF INTERRUPT SERVICE ROUTINES *********/
/* Replace the interrupt function names with the
*/
/* appropriate names depending on interrupt source. */
/* The names of various interrupt functions for
/* each device are defined in the linker script.
*/
*/
/* Interrupt Service Routine 1
/* No fast context save, and no variables stacked
*/
*/
void __attribute__((__interrupt__)) _ADCInterrupt(void)
{
/* Interrupt Service Routine code goes here
*/
}
/* Interrupt Service Routine 2
/* Fast context save (using push.s and pop.s)
*/
*/
void __attribute__((__interrupt__, __shadow__)) _T1Interrupt(void)
{
/* Interrupt Service Routine code goes here
*/
}
/* Interrupt Service Routine 3: INT0Interrupt
/* Save and restore variables var1, var2, etc.
*/
*/
void __attribute__((__interrupt__(__save__(variable1,variable2))))
_INT0Interrupt(void)
{
/* Interrupt Service Routine code goes here
*/
}
/********* END OF INTERRUPT SERVICE ROUTINES ********/
2003 Microchip Technology Inc.
DS70094B-page 29
dsPIC™ Language Tools Getting Started
3.3
USING THE TEMPLATE IN A NEW PROJECT
For this tutorial, copy the template described above to a new project directory, following
these steps. Go to Windows® Explorer for these folder/file operations.
1. Make a new folder named \T1_Interrupt in the \Examples directory under
the MPLAB C30 installation directory.
2. Copy C:\pic30_tools\support\templates\c\temp_6014.C to the new
\T1_Interrupt folder.
3. Rename the copied template file temp_6014.c in the \T1_Interrupt folder
to T1Clock.c.
4. Return to MPLAB IDE.
Use the project wizard to create a new project in this directory, using this as the only
source file, then add the linker script for the dsPIC30F6014 as done in Chapter 2. After
double clicking on the file name T1Clock.c in the Project window, the desktop should
look something like this:
FIGURE 3-1:
DS70094B-page 30
VIEW T1CLOCK.C
2003 Microchip Technology Inc.
Tutorial 2 - Real-Time Interrupt
Some of the header comments for this generic template can now be removed and
application specific information entered for the new project. The header area at the
beginning of the file should contain information on the new project. After editing is
finished, it might look something like this:
FIGURE 3-2:
EDITED T1CLOCK.C
For this tutorial, one constant, two variables and an array need to be defined. The
constants defined in the template are named CONSTANT1 and CONSTANT2.
Comment those out, and below the CONSTANT2 line add a comment and the
definition for TMR1_PERIOD 0x1388:
/* Timer1 period for 1 ms with FOSC = 20 MHz */
#define TMR1_PERIOD 0x1388
Note:
The period 0x1388 = 5000 decimal. The timer will count at a rate one fourth
the oscillator frequency. 5000 cycles at 5 MHz (the 20 MHz oscillator is
divided by four) yields a time-out for the counter at every 1 ms.
Define some variables to track the code operation in this example. Position these in the
GLOBAL DEFINITIONS area, after the definition of variable3. Add two new integer
variables, main_counter and irq_counter. Then, for the interrupt timer routine,
create a structure of three unsigned integer variable elements, timer, ticks and
seconds, named RTclock:
EXAMPLE 3-3:
VARIABLE DEFINITIONS
/* Define global variables without attributes
*/
int variable3;
int main_counter;
int irq_counter;
struct clockType
{
unsigned int timer;
unsigned int ticks;
unsigned int seconds;
} RTclock;
2003 Microchip Technology Inc.
/* countdown timer, milliseconds */
/* absolute time, milliseconds */
/* absolute time, seconds */
DS70094B-page 31
dsPIC™ Language Tools Getting Started
The other template code in this tutorial can be left in or commented out. It is probably
better to comment it out at this time since these definitions will get compiled and take
up memory space. Make sure to comment out all the sample arrays, since they use the
macros which can be commented out. Also, as the code grows, it may be difficult to
remember which code is used by the application and which was part of the original
template.
Note:
When using the template, remember that when beginning to code the
application, only a few elements of the template may be needed. It may be
helpful to comment out those portions of code that are not being used so
that later, when similar elements are needed, they can be referred back to
as models.
After the section labelled END OF GLOBAL DEFINITIONS type in this routine to
initialize Timer 1 as an interrupt timer using the internal clock (the bolded text is the
code that should be typed in):
EXAMPLE 3-4:
RESET_CLOCK CODE
/************** END OF GLOBAL DEFINITIONS ***********/
void reset_clock(void)
{
RTclock.timer = 0;
RTclock.ticks = 0;
RTclock.seconds = 0;
TMR1 = 0;
PR1 = TMR1_PERIOD;
T1CONbits.TCS = 0;
IPC0bits.T1IP = 4;
IFS0bits.T1IF = 0;
IEC0bits.T1IE = 1;
SRbits.IPL = 3;
T1CONbits.TON = 1;
}
/* clear software registers */
/*
/*
/*
/*
/*
/*
/*
/*
clear timer1 register */
set period1 register */
set internal clock source */
set priority level */
clear interrupt flag */
enable interrupts */
enable CPU priority levels 4-7 */
start the timer */
/************* START OF MAIN FUNCTION ***************/
This routine uses special function register names, such as TMR1 and T1CONbits.TCS
that are defined in the header file p30F6014.h. Refer to the data sheet for more
information on these control bits and registers for Timer 1.
DS70094B-page 32
2003 Microchip Technology Inc.
Tutorial 2 - Real-Time Interrupt
A main routine and an interrupt service routine may need to be written. The most
complex routine is the interrupt service routine. It is executed when Timer 1 counts
down 0x1388 cycles. It increments a counter sticks at each of these 1 ms interrupt
until it exceeds one thousand. Then it increments the seconds variable in the
RTclock structure and resets sticks. This routine should count time in seconds. In
the section labelled “START OF INTERRUPT SERVICE ROUTINES” where a template
for the _T1Interrupt() code is written, replace the comment
“/* Interrupt Service Routine code goes here */”
with these lines of code (added code is bold):
EXAMPLE 3-5:
INTERRUPT SERVICE ROUTINE
/* Interrupt Service Routine 2
/* Fast context save (using push.s and pop.s)
*/
*/
void __attribute__((__interrupt__, __shadow__)) _T1Interrupt(void)
{
static int sticks=0;
irq_counter++;
if (RTclock.timer > 0)
RTclock.timer -= 1;
/* if timer is active */
/* decrement it */
RTclock.ticks++;
/* increment ticks counter */
if (sticks++ == 1000)
{
sticks = 0;
RTclock.seconds++;
}
/* if time to rollover */
/* clear seconds ticks */
/* and increment seconds */
IFS0bits.T1IF = 0;
/* clear interrupt flag */
}
/* Interrupt Service Routine 3: INT0Interrupt
/* Save and restore variables var1, var2, etc.
*/
*/
There are three sample interrupt functions in the template file. Comment out
_INT0Interrupt() because it uses two of the template file sample variables and, as
a result, will not compile. _ADCInterrupt() can be commented out too, since it will
not be used in this tutorial.
By comparison to the Timer 1 interrupt code, the main() code is simple. Type this in
for the body, replacing the line “/* code goes here */” (added code is bold):
EXAMPLE 3-6:
MAIN CODE
/************* START OF MAIN FUNCTION ***************/
int main ( void )
{
reset_clock();
for (;;)
main_counter++;
}
/****** START OF INTERRUPT SERVICE ROUTINES *********/
The main() code is simply a call to our Timer 1 initialization routine, followed by an
infinite loop, allowing the Timer 1 interrupt to function. Typically, an application that
made use of this timer would be placed in this loop in place of this test variable,
main_counter.
2003 Microchip Technology Inc.
DS70094B-page 33
dsPIC™ Language Tools Getting Started
The final code should now look like this:
EXAMPLE 3-7:
FINAL C CODE FILE
/***********************************************************************
*
*
*
Author:
F. Bar
*
*
Company:
Widgets, Inc.
*
*
Filename:
T1Clock.c
*
*
Date:
7/7/2003
*
*
File Version:
1.00
*
*
Other Files Required: p30F6014.gld, libpic30.a
*
*
Tools Used: MPLAB GL -> 6.30
*
*
Compiler -> 1.10
*
*
Assembler -> 1.10
*
*
Linker
-> 1.10
*
***********************************************************************/
#include "c:\pic30_tools\support\h\p30F6014.h"
/* Define constants here
/* #define CONSTANT1 10
#define CONSTANT2 20
/* Timer1 period for 1 ms with FOSC = 20 MHz
#define TMR1_PERIOD 0x1388
*/
*/
*/
/* Define macros to simplify attribute declarations */
#define ModBuf_X(k) __attribute__((__section__(".xbss"), __aligned__(k)))
#define ModBuf_Y(k) __attribute__((__section__(".ybss"), __aligned__(k)))
/************* START OF GLOBAL DEFINITIONS **********/
/* Define arrays: array1[], array2[], etc.
*/
/* with attributes, as given below
*/
/* either using the entire attribute
*/
/*
int array1[CONSTANT1] __attribute__((__section__(".xbss"), __aligned__(32)));
int array2[CONSTANT1] __attribute__((__section__(".ybss"), __aligned__(32)));
*/
/* or using macros defined above
*/
/* int array3[CONSTANT1] ModBuf_X(32);
int array4[CONSTANT1] ModBuf_Y(32);
*/
/* Define arrays without attributes
*/
/* int array5[CONSTANT2]; */ /* array5 is NOT an aligned buffer */
/* ------------------------------------------------ */
/* Define global variables with attributes
*/
/* int variable1 __attribute__((__section__(".xbss")));
int variable2 __attribute__((__section__(".ybss")));*/
/* Define global variables without attributes
/* int variable3; */
int main_counter;
int irq_counter;
struct clockType
{
unsigned int timer;
unsigned int ticks;
unsigned int seconds;
} RTclock;
*/
/* countdown timer, milliseconds */
/* absolute time, milliseconds */
/* absolute time, seconds */
/************** END OF GLOBAL DEFINITIONS ***********/
void reset_clock(void)
{
RTclock.timer = 0;
RTclock.ticks = 0;
RTclock.seconds = 0;
TMR1 = 0;
PR1 = TMR1_PERIOD;
T1CONbits.TCS = 0;
IPC0bits.T1IP = 4;
IFS0bits.T1IF = 0;
IEC0bits.T1IE = 1;
SRbits.IPL = 3;
T1CONbits.TON = 1;
}
DS70094B-page 34
/* clear software registers */
/*
/*
/*
/*
/*
/*
/*
/*
clear timer1 register */
set period1 register */
set internal clock source */
set priority level */
clear interrupt flag */
enable interrupts */
enable CPU priority levels 4-7 */
start the timer */
2003 Microchip Technology Inc.
Tutorial 2 - Real-Time Interrupt
EXAMPLE 3-7:
FINAL C CODE FILE (CONTINUED)
/************* START OF MAIN FUNCTION ***************/
int main ( void )
{
reset_clock();
while (1)
main_counter++;
}
/****** START OF INTERRUPT SERVICE ROUTINES *********/
/* Interrupt Service Routine 1
*/
/* No fast context save, and no variables stacked
*/
/* void __attribute__((__interrupt__)) _ADCInterrupt(void)
*/
/* Interrupt Service Routine 2
/* Fast context save (using push.s and pop.s)
*/
*/
void __attribute__((__interrupt__, __shadow__)) _T1Interrupt(void)
{
static int sticks=0;
irq_counter++;
if (RTclock.timer > 0)
RTclock.timer -= 1;
/* if countdown timer is active */
/* decrement it */
RTclock.ticks++;
/* increment ticks counter */
if (sticks++ > 1000)
{
sticks = 0;
RTclock.seconds++;
}
/* if time to rollover */
/* clear seconds ticks */
/* and increment seconds */
IFS0bits.T1IF = 0;
/* clear interrupt flag */
return;
}
/* Interrupt Service Routine 3: INT0Interrupt
*/
/* Save and restore variables var1, var2, etc.
*/
/* void __attribute__((__interrupt__(__save__(variable1)))) _INT0Interrupt(void)
*/
/********* END OF INTERRUPT SERVICE ROUTINES ********/
If everything is typed correctly, then selecting Project>Build All should result in a
successful compilation. Double click on any errors appearing in the output window to
return to the source code to fix typos and rebuild the project until it builds with no errors.
2003 Microchip Technology Inc.
DS70094B-page 35
dsPIC™ Language Tools Getting Started
3.4
DEBUGGING WITH THE MPLAB SIM30 SIMULATOR
The MPLAB SIM30 simulator can now be used to test the code. Make sure that
Debugger>Select Tool>MPLAB SIM30 is selected. Then set the processor clock speed
for the simulator by selecting Debugger>Settings. The Oscillator tab is a dialog to set
the clock frequency of the simulated dsPIC30F6014. Set it to 20 MHz.
Note:
The simulator runs at a speed determined by the PC, so it will not run at the
actual dsPIC30F MCU speed as set by the clock in this dialog. However, all
timing calculations are based on this clock setting, so when timing
measurements are made using the simulator, times will correspond to those
of an actual device running at this frequency.
FIGURE 3-3:
STIMULUS OSCILLATOR FREQUENCY
One way to measure time with the simulator is to use the Stopwatch. Select
Debugger>Stopwatch to view the Stopwatch dialog, and make sure that the box
labeled “Clear Simulation on Reset” is checked.
FIGURE 3-4:
DS70094B-page 36
SIMULATOR STOPWATCH
2003 Microchip Technology Inc.
Tutorial 2 - Real-Time Interrupt
Often a good first test is to verify that the program minimally runs. For this purpose, set
a breakpoint at the line in main() that increments main_counter (right mouse click
on the line and select Set Breakpoint), then press the Run icon or select
Debugger>Run. The Stopwatch and the screen should like this after the breakpoint is
reached.
FIGURE 3-5:
TIME MEASUREMENT
If everything looks OK, then a watch window can be set to inspect the program’s
variables. Select View>Watch to bring up the watch window, then add the variable
RTclock so it looks like this:
FIGURE 3-6:
2003 Microchip Technology Inc.
WATCH
DS70094B-page 37
dsPIC™ Language Tools Getting Started
RTclock is a structure, as indicated by the small plus symbol in the box to the left of
its name. Click on the box to expand the structure so it looks like this:
FIGURE 3-7:
WATCH STRUCTURE
Also add the variables sticks, irq_counter, and main_counter to the watch
window.
FIGURE 3-8:
WATCH VARIABLES
The Value column may be expanded wider in order to read the text on the sticks
variable. Note that it says “Out of Scope.” This means, that unlike RTclock,
irq_counter, and main_counter, this is not a global variable, and its value can only
be accessed while the function _T1Interrupt()is executing.
Note:
The Address column for sticks does not have a value. This is another
indication that sticks is a local variable.
When inspecting the variables in the watch window at this first breakpoint, all of them
should be equal to zero. This is to be expected, since Timer 1 just got initialized and
counter has not yet been incremented for the first time.
Press the Step-Into icon to step once around the main() loop. The value of
main_counter should now show 0001. The interrupt routine has not yet fired.
Looking at the Stopwatch window, the elapsed time only increments by a microsecond
each time through the main() loop. To reach the first interrupt we’d have to step a
thousand times (1000 x 1 us = 1 ms).
DS70094B-page 38
2003 Microchip Technology Inc.
Tutorial 2 - Real-Time Interrupt
In order to see that the interrupt seems to be working as designed, remove the breakpoint at main_counter++ by clicking on the highlighted line with the right mouse button and select Remove Breakpoint. Now select Enable Breakpoint in the right mouse
menu to put a breakpoint in the interrupt service routine at the irq_counter++ statement, then press Run. The Stopwatch should look like this:
FIGURE 3-9:
STOPWATCH AT FIRST INTERRUPT
The value shown in the Time window is 1.0304 ms. This is about what was expected,
since the interrupt should happen every millisecond. There was some time since
RESET that was counted by the Stopwatch, including the C start-up code and the Timer
1 initialization.
Look at the Watch window. The variable main_counter is showing a value of 0x3E8.
Change the radix of this display to decimal by placing the cursor over main_counter
in the Watch window, using the right mouse button, choose “Properties”. A dialog will
be displayed. Go to the Format pull-down and select Decimal, then press OK.
FIGURE 3-10:
SET WATCH RADIX
The main_counter value should now show 1000. Press the Step-Into icon a few more
times to see the changing variables, especially sticks and irq_counter, which are
incrementing each time the interrupt happens.
2003 Microchip Technology Inc.
DS70094B-page 39
dsPIC™ Language Tools Getting Started
Remove the breakpoint from the irq_counter++; line, and put a breakpoint inside
the conditional statement that increments sticks, at the line sticks = 0; Press Run
to run and halt at this breakpoint. The window should look like this:
FIGURE 3-11:
MEASURE INTERRUPT PERIOD
The Stopwatch Time window shows 1.0012346 seconds, which is close to a one
second interrupt. A good time measurement would be to measure the time to the next
interrupt. That value could then be subtracted from the current time. Or, since it doesn’t
matter how much time it took to get here – the main interest is the time between
interrupts – press Zero on the Stopwatch and then press Run.
Note:
3.5
The Stopwatch always tracks total time in the windows on the right side of
the dialog. The left windows can be used to time individual measurements.
Pressing zero will not cause the total time to change.
EXPLORING FURTHER
Measure the overhead of the interrupt, calculate how this will affect the timing, and try
to adjust the constant TMR1_Period to adjust the interrupt to get better 1 second
accuracy.
What is the maximum time (in minutes) measured by this routine? What can be done
to extend it?
Add a routine that outputs a two millisecond pulse every second from a port. Verify the
pulse duration with the stopwatch.
DS70094B-page 40
2003 Microchip Technology Inc.
dsPIC™ LANGUAGE TOOLS
GETTING STARTED
Chapter 4. Tutorial 3 - Mixed C and Assembly Files
4.1
INTRODUCTION
This tutorial will show how to make a project that uses an assembly language routine
that is called from a C source file.
4.2
GETTING PROJECT SOURCE FILES
The files for this tutorial are available in the \Examples folder and are called
example3.c, a C source code file, and modulo.s, an assembly language file. Create
a folder in the \Examples folder called \DSP_ASM and copy these two files to that new
folder.
For reference, Example 4-1and Example 4-2 show listings of these two files.
2003 Microchip Technology Inc.
DS70094B-page 41
dsPIC™ Language Tools Getting Started
EXAMPLE 4-1:
C SOURCE FILE
/**********************************************************************
*
Filename:
example3.c
*
*
Date:
04/16/2003
*
*
File Version:
1.00
*
*
Tools used: MPLAB
-> 6.30
*
*
Compiler -> 1.10
*
*
Assembler -> 1.10
*
*
Linker
-> 1.10
*
*
Linker File:
p30f6014.gld
*
***********************************************************************/
#include "p30f6014.h"
#include <stdio.h>
/* Length of output buffer (in words) */
#define PRODLEN 20
/* source arrays of 16-bit elements */
unsigned int array1[PRODLEN/2] __attribute__((__section__(".xbss"), aligned(32)));
unsigned int array2[PRODLEN/2] __attribute__((__section__(".ybss"), aligned(32)));
/* output array of 32-bit products defined here */
long array3[PRODLEN/2];
/* array3 is NOT a circular buffer */
/* Pointer for traversing array */
unsigned int array_index;
/* 'Point-by-point array multiplication' assembly function prototype */
extern void modulo( unsigned int *, unsigned int *, unsigned int *, unsigned int );
int main ( void )
{
/* Set up Modulo addressing for X AGU using W8 and for Y AGU using W10 */
/* Actual Modulo Mode will be turned on in the assembly language routine */
CORCON |=
XMODSRT =
XMODEND =
YMODSRT =
YMODEND =
0x0001;
(unsigned
(unsigned
(unsigned
(unsigned
/* Enable integer arithmetic */
int)array1;
int)array1 + PRODLEN - 1;
int)array2;
int)array2 + PRODLEN - 1;
/* Initialize 10-element arrays, array1 and array2 */
/* to values 1, 2, ...., 10 */
while (1)
/* just do this over and over */
{
for (array_index = 0; array_index < PRODLEN/2; array_index++)
{
array1[array_index] = array1[array_index] + array_index + 1;
array2[array_index] = array2[array_index] + (array_index+1) * 3;
}
/*
/*
/*
/*
Call assembly subroutine to do point-by-point multiply
of array1 and array2, with 4 parameters:
start addresses of array1, array2 and array3, and PRODLEN-1
in that order
modulo( array1, array2, array3, PRODLEN-1 );
}
*/
*/
*/
*/
}
DS70094B-page 42
2003 Microchip Technology Inc.
Tutorial 3 - Mixed C and Assembly Files
EXAMPLE 4-2:
MODULO.S ASM SOURCE FILE
/**********************************************************************
*
Filename:
modulo.s
*
*
Date:
04/27/2003
*
*
File Version:
1.00
*
*
*
*
Tools used: MPLAB
-> 6.30
*
*
Compiler -> 1.10
*
*
Assembler -> 1.10
*
*
Linker
-> 1.10
*
*
*
*
Linker File:
p30f6014.gld
*
*
Description: Assembly routine used in example3.C
*
**********************************************************************/
.text
.global _modulo
_modulo:
; If any of the registers W8 - W15 are used, they should be saved
; W0 - W7 may be used without saving
PUSH
W8
PUSH
W10
; turn on modulo addressing
MOV
#0xC0A8, W8
MOV
W8, MODCON
; The 3 pointers were passed in W0, W1 and W2 when function was called
; Transfer pointers to appropriate registers for MPY
MOV
W0, W8
; Initializing X pointer
MOV
W1, W10
; Initializing Y pointer
; Clear Accumulator and prefetch 1st pair of numbers
CLR
A, [W8]+=2, W4, [W10]+=2, W7
LSR
RCALL
INC2
RCALL
W3, W3
array_loop ; do multiply set
W8, W8
; Change alignment of X pointer
array_loop ; second multiply set
POP
POP
W10
W8
RETURN
; Return to main C program
array_loop:
DO
; Set up DO loop with count 'PRODLEN - 1' (passed in W3)
W3,
here
; Do
MPY
a point-by-point multiply
W4*W7, A, [W8]+=2, W4, [W10]+=2, W7
; Store result in a 32-bit array pointed by W2
MOV
ACCAL, W5
MOV
W5, [W2++]
here:
MOV
MOV
ACCAH, W5
W5, [W2++]
; turn off modulo addressing
CLR
MODCON
RETURN
.end
2003 Microchip Technology Inc.
DS70094B-page 43
dsPIC™ Language Tools Getting Started
4.3
CREATING AND BUILDING THE PROJECT
Using the Project Wizard, create a new project with these two source files and add the
same linker script as the preceding two tutorials, p30f6014.gld. The project window
should look like this:
FIGURE 4-1:
PROJECT WINDOW
This tutorial will use the standard I/O function printf() to display messages to the
output window. In order to use printf(), the build options for the linker need to have
the heap enabled. Make sure that the linker build option is set as shown in Figure 2-17
with 512 bytes allocated for the heap.
When building the project (Project>Build All), it should compile with no error messages.
If an error is received, make sure the project is set up with the same options as for the
previous two tutorials.
This tutorial sets up three arrays. It fills two of them with a test numerical sequence,
then calls an assembly language routine that multiplies the values in the two 16-bit
arrays and puts the result into the third 32-bit array. Using modulo arithmetic for
addressing, the two source arrays are traversed twice to generate two sets of products
in the output array, with the pointer to one array adjusted at the second pass through
the multiply loop to change the alignment between the multipliers. Using an assembly
language routine ensures that the arithmetic will be done using the DSP features of the
dsPIC30F6014.
The assembly language routine takes four parameters: the addresses of each of the
three arrays and the array length. It returns its result in the product array.
This routine runs in a continual loop, with the source arrays getting increasingly larger
numbers as the program repeatedly executes the main endless loop.
DS70094B-page 44
2003 Microchip Technology Inc.
Tutorial 3 - Mixed C and Assembly Files
4.4
EXAMINING THE PROGRAM
Once the project is set up and successfully built, the operation of the program can be
inspected. Set and run to a breakpoint on the function that calls the assembly language
routine, modulo().
FIGURE 4-2:
BREAKPOINT
Set up a watch window to look at the variables involved in this calculation. Add the three
arrays, array1, array2 and array3. Also add the SFRs (Special Function
Registers), ACCA, WREG8 and WREG10. The watch window should look like this:
FIGURE 4-3:
2003 Microchip Technology Inc.
WATCH WINDOW
DS70094B-page 45
dsPIC™ Language Tools Getting Started
Click on the plus symbol to the left of the symbol name to expand the arrays. At this
point in the program, both array1 and array2 should have been set up with initial
values, but array3 should be all zeros, since the modulo() routine has not yet been
called.
FIGURE 4-4:
ARRAY3
Right click on any element in the arrays to change the radix of the display. Change the
radix for all three arrays to decimal.
Note:
DS70094B-page 46
Changing the radix for any element of an array changes the radix for all
elements in that array.
2003 Microchip Technology Inc.
Tutorial 3 - Mixed C and Assembly Files
Set a breakpoint in the modulo.s file at the start of the DO loop.
FIGURE 4-5:
BREAKPOINT IN ASSEMBLY CODE FILE
Run to the breakpoint and scroll the watch window to look at array3. It should still be
all zeroes. Press Run again, to run once through the DO loop. Now the first half of
array3 should show values representing the product of each element pair from the
source arrays:
FIGURE 4-6:
2003 Microchip Technology Inc.
ARRAY3 RESULTS - 1ST PASS
DS70094B-page 47
dsPIC™ Language Tools Getting Started
Press Run again to see the results for the second pass through the DO loop:
FIGURE 4-7:
ARRAY3 RESULTS - 2ND PASS
Remove the breakpoint from modulo.s and press Run to see the next time through
the loop. Press Run a few more times to see the values change with subsequent
executions of this multiplication process.
With Watch windows, data can be examined as breakpoints are run and halted. The
simulator can also output data as it executes, providing a log of data that can be
inspected and sent to other tools for graphing and analysis. Insert a printf()
statement after the modulo() function call to monitor the values in the output array.
The code should look like this (added code is bold):
EXAMPLE 4-3:
printf() MONITOR
modulo( array1, array2, array3, PRODLEN-1 );
printf("Product Array\n");
for (array_index=0; array_index<PRODLEN/2; array_index++)
printf("%ld\n",array3[array_index]);
DS70094B-page 48
2003 Microchip Technology Inc.
Tutorial 3 - Mixed C and Assembly Files
The printf() function uses the UART1 functions of the dsPIC being simulated to
write messages either to a file or to the output window. Select Debugger>Settings to
bring up the simulator Settings dialog. Go to the tab labelled CLIB I/O, click on the
check Enable Standard C Library I/O, and then select the radio button to send text from
the printf() statement to the output window.
FIGURE 4-8:
CLIB I/O
Now when the simulator is recompiled and run, a log of the contents of array3 will be
generated in the output window. Press Run, let it run for a few seconds, then press Halt.
If the output window is not present, enable it on View>Output.
FIGURE 4-9:
2003 Microchip Technology Inc.
printf() OUTPUT
DS70094B-page 49
dsPIC™ Language Tools Getting Started
4.5
EXPLORING FURTHER
Some of the other DSP instructions can be tried to further process the numbers in these
arrays.
Use the printf() function to output lists of values that can then be imported into a
spreadsheet. Graph the values.
Further generalize the code so that all of the modulo indexing is set up from within
modulo.s (i.e., convert these lines from Example 4-1 C Source File into assembly
code that sets up the modulo addressing parameters from the parameters passed into
the array).
XMODSRT
XMODEND
YMODSRT
YMODEND
4.6
=
=
=
=
(unsigned
(unsigned
(unsigned
(unsigned
int)array1;
int)array1 + PRODLEN - 1;
int)array2;
int)array2 + PRODLEN - 1;
WHERE TO GO FROM HERE
These tutorials were designed to gain familiarity using the MPLAB C30 compiler in the
MPLAB IDE environment. There are many features of MPLAB IDE and the MPLAB
C30 compiler that were not covered here. For more information, reference the current
MPLAB IDE on-line help, MPLAB C30 C Compiler User’s Guide and MPLAB ASM30,
MPLAB LINK30 and Utilities User’s Guide to start using these tools for individual applications.
Instant help can be obtained from MPLAB IDE’s on-line help or by logging on to
Microchip’s web conference for MPLAB C products at www.microchip.com. Go to the
Technical Support section and then to the On-line Discussion Groups. The
Development Systems web board also has a section devoted to MPLAB C30 compiler
discussion.
By subscribing to the Customer Change Notification service on Microchip’s web site,
customers can register to be notified of changes to the MPLAB C30 C compiler.
Choose the MPLAB C compiler category in Development Tools to receive notices when
new versions are available and to receive timely information on the MPLAB C30
compiler.
DS70094B-page 50
2003 Microchip Technology Inc.
dsPIC™ LANGUAGE TOOLS
GETTING STARTED
Index
A
N
Arrays ...................................................................... 45
New Project ............................................................... 4
B
O
Breakpoints ................................................. 16, 18, 45
Build Errors ............................................................. 15
Build Options ........................................................... 10
Build Project ............................................................ 14
Oscillator Frequency, Stimulus ............................... 36
Output Window ........................................................ 14
P
CLIB I/O .................................................................. 49
Clock Reset ............................................................. 32
Creating a Project ..................................................... 3
printf() ...................................................................... 44
printf() output ........................................................... 49
Program Memory Window ....................................... 22
Project Window ................................................... 9, 44
Project Wizard ..................................................... 4, 44
D
R
Disassembly Window .............................................. 21
Real-Time Interrupt Using a Template File ............. 25
I
S
Installing MPLAB ASM30, MPLAB LINK30 ............... 1
Installing MPLAB C30 ............................................... 1
Interrupt Service Routine ........................................ 33
Stopwatch ............................................................... 36
C
L
Listing Files ............................................................. 20
M
Map Files ................................................................ 20
Mixed C and Assembly Files ................................... 41
modulo() .................................................................. 45
MPLAB SIM30 Simulator ........................................ 16
2003 Microchip Technology Inc.
T
Template Files ......................................................... 25
U
Uninstalling MPLAB C30 ........................................... 1
V
Variable Definitions ................................................. 31
W
Watch Window ...................................... 17, 18, 37, 45
DS70094B-page 51
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