ECE 353

WinAVR and C Debugging Tutorial

By Adam Bailin

ECE 353 Fall ‘06

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Introduction WinAVR is a set of developing tools for

Atmel AVR RISC microprocessors

Programs written in C, compiled with GCC and avr-libc

Open source, obtained at: winavr.sourceforge.net

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Installing Fairly easy to install (for use at home) http://winavr.sourceforge.net/ Comes with all the tools you need:

Programmer’s Notepad, MFile

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Programmer’s Notepad Programmer’s Notepad is the main tool

you will be using to write your C code Just like any other compiler

• syntax highlighting• Support for different programming languages• Ability to compile your code (using gcc

compiler)

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Adding external tools In Programmer’s Notepad, select Tools->Options,

and select “Tools” on the left side of screen

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Adding external tools (continued) Select a Scheme (C/C++) Click on “Add” “Name” is an identifier for this

tool Command is the command

used Folder should be %d (Path of

file) This tool will call “make

extcoff”, and is now available under “Tools” menu

We will need this later for debugging in AVR Studio

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Example C Program// blinky.c#include <avr/io.h> // Standard AVR header#include <avr/delay.h> // Delay loop functions

int main(void) {

DDRA = 0xFF; // PORTA is output while (1) { for (int i=1; i<=128; i*=2) {

PORTA = i;_delay_loop_2(30000);

} for (int i=128; i>1; i/=2) {

PORTA = i;_delay_loop_2(30000);

}} // end while

}

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Building your source Write your C source, save as blinky.c Open up MFile

• Makefile -> Main File Name = blinky (no .c)• Makefile -> MCU Type = atmega32

Other values should be fine at default File -> Save As to blinky.c directory In Programmer’s Notepad: Select Tools

->Make All

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MFile Simple program to make Makefiles for

compiling your C code A Makefile is a configuration file that tells

the compiler how to compile your code• What chip you’re using (atmega32)• Target filename (blinky.c)

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GNU Make WinAVR uses “Makefiles” when building

projects, with GNU Make

GNU Make builds dependencies and then source files

Will only rebuild files from updated or new source (saves time)

Very powerful tool: see C:\WinAVR\doc\gnu\make.html for more info

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Makefiles (continued)

Makefiles are tab-sensitive: tab != space

Lines starting with tab are executed as commands

Misuse of tabs will lead to “improper separator” error

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Example Makefile## ‘all’ and ‘clean’ targets must be defined!

# ‘make’ or ‘make all’ will build dependencies in the order they are given

all: begin project2 end

begin:

@echo “Starting build”

project2:

avr-gcc project2.c

end:

@echo “Build complete”

clean:

rm project2.o

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Programming your ATmega32 To program your chip with the C code you

wrote:• Go to AVR Studio• Connect to your chip using JTAG ICE• Go to Fuses tab, make sure Ext Clock is set• In Program tab, flash your chip with the .hex

file you compiled in Programmer’s Notepad• That’s it!

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C Debugging in AVR Studio

Use the editor to edit the flags in makefile:

DEBUG = stabs // will allow for C debugging

OPT = 0 // will turn off compiler’s optimization

Save the makefile

AVR Studio provides a way to debug both the C source code and the assembly code. To do that you just need to change the type of the COF file generated by the compiler.

Open the Programmer’s Notepad (WinAVR)

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Building C code for Debugging

Go to Tools Options Tools Pull down the Schemes window and click on

C/C++ option A make extcoff option will appear; click OK Click on Tools again Click on make extcoff to generate the COF file

(this will generate the correct debug file for AVR Studio that includes the C code information)

In the Programmer’s Notepad (WinAVR):

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Debugging in AVR Studio Connect Olimex to PC and JTAG Open the AVR Studio

• Open the COF file

(it will guide you to select the debug platform (JTAG) and the device (Atmega 32))

• The C code will appear in the main window

• Optional (useful!) view the assembly code:

go to View Dissassembler

• You can put assembly code next to C code

(tile vertically) and step through both codes!

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Additional Information Additional Information can be found at the

WinAVR website:

winavr.sourceforge.net