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Getting started programming the Atmel

ATmega32 in assembly using AVRStudio

by

Dr.-Ing. Joerg MossbruckerEECS Department

Milwaukee School of Engineering

August 20, 2005

This manual covers the following:

• How to create and code a new project

• How to build and simulate the tutorial

• How to download and execute the tutorial on the hardware platform

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1 New Project

- Go to “D:\Atmel\AVRTools\AvrStudio4”

- and double-click “AVRStudio.exe”

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- click “Create New Project”

- and fill out the dialog box as shown above.; make sure that the Location is set as above and that

“Create initial file” is checked. Click “Next>>”

- and select “AVR Simulator” and “ATmega32”. Click “Finish”. This closes the dialog box.

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AVRStudio is an integrated development environment. The user interface consists of the follow-

ing area:

A: The workspace; this area will either show the structure of the current project or the simulator

B: The source code window(s)

C: The status window

Please note that depending on the configuration of AVRStudio many more windows might appear.

AB

C

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Click on the source code window (B) and input the following assembly program:

; Copyright (c) 2004 Joerg Mossbrucker <mossbruc@msoe.edu>

.include "m32def.inc" ; include the register def file

.equ Zero = 0

.equ Time = 255 ; this used in a timing loop

.def Counter= r21 ; use r21 as the counter register

.dseg ; data segment

.org 0x60 ; set SRAM address to hex 60Data: .byte 1 ; reserve a byte at SRAM

.cseg ; code segment

.org 0 ; set the RESET vector torjmp Reset ; the beginning of our code

.org 0x2A ; set Program Counter to hex 2AReset:

ldi r20,0xff ; load immediate 0xff into r20out DDRB,r20 ; output that on DDRB

ldi r20,Zero ; load r20 with 0sts Data,r20 ; store r20 in Dataout PORTB,r20 ; and out to PORTB

start: ldi Counter,time ; load Counter with time

loop: dec Counter ; decrement Counterbrne loop ; branch if not equal back to loop

lds r20,Data ; load r20 with Datainc r20 ; increment r20sts Data,r20 ; store r20 into Dataout PORTB,r20 ; out r20 on PORTB

rjmp start ; back to start

After coding save your project by clicking “File->Save All”.

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The source file is in AVR assembly language and needs to be assembled into an executable. Click

“Project->Build”

The status area will show if the assembly process was successful

To start the simulator click “Project-> Build and Run”

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This assembles and starts the simulator

The simulator is capable of simulating a variety of AVR microcontroller. Click “Debug -> Select

Platform and Device”

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and select the appropriate microcontroller

- Click “Finish”. Click “Debug -> Simulator Options”

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and change the settings accordingly

The I/O view in the workspace contains every register of the selected microcontroller.

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The debug menu contains every command for debugging using the simulator, such as single step-

ping through the code

The I/O view reflects the changes of every step in the program

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By enabling the Watch view (click “View -> Watch”) variables can be traced throughout the pro-

gram by simply selecting the variable name

right-click and select “Add to Watch: Counter”

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which adds the variable to the watch list

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2 Downloading

Connect the AVR ISP programmer to the ISP header on the development platform and to an open

serial port on a PC. Click “Tools -> STK500/AVR ISP/JTAG ICE...”

AVR ISP will then connect with the microcontroller. Hit “Cancel” if you are asked to upgrade the

Firmware of AVRISP.

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The AVR microcontroller has many different modes of operation. Make sure that the fuse settings

are as follows (Click “Fuses”)

and that the Lock Bits are as shown (click “LockBits”)

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To download an executable to the microcontroller, click “Program” and select the appropriate

.hex-file in the Flash section.

click “Program” and the executable is downloaded and executed on the micro controller.