ATMEL AVR start programming in C.pdf

AVR030: Getting Started with C for AVR

Features

• How to Open a New Project

• Description of Option Settings

• Linker Command File Examples

• Writing and Compiling the C Code

• How to Load the Executable File Into the

STK200 Starter Kit

Preparations

The IAR compiler is shipped with a hard-

ware lock dongle. This dongle must be

connected to the parallel port. Before the

dongle can be used, a windows driver

must be installed. Please see the

instructions included with the dongle for

how to install the windows driver.

8-bit

Microcontroller

Application

Note

Introduction

The purpose of this application note is to

guide new users through the initial set-

tings of the Embedded Workbench from

IAR and compile a simple C program.

The application note shows how to set

up the compiler to generate an execut-

able hex file and how to download this

file into the device. The example

described in this application note is writ-

ten for the AT90S2313 using the

STK200 starter kit or alternatively an

emulator.

Creating a New Project

When the preparations are ready, open

the IAR Embedded Workbench. To cre-

ate a new project, go to the “File” menu

and select “New” and then “Project ” . The

dialog box shown in Figure 1 appears. In

this dialog box, first make a folder

“C:\AVR030” and then type “Getting

Started” in the “File name” window. This

project should be created in the in the

“C:\AVR030” folder.

Figure 1. Create the Project File

Rev. 1483A–09/99

Settings in “Project-> Options”

Before any code can be compiled and linked, the options

for the compiler and linker must be set up correctly. By

default, it is possible to select two different targets in the

project window. The two selections are target “Release”,

and target “Debug”. The debug target is normally used

when running the code in a simulator or emulator, while the

release target is normally used when producing a code that

can be executed in a real device. The settings done in the

“Project->Options” menu are individual for both targets.

Thus, it is necessary to set all options twice when using

both targets. The main difference between the two targets

is the format of the output file.

It is also possible to add more targets which options can be

customized to a specific AVR (simulated, emulated or the

real device). Common and different source files may be

included in the different targets. A folder will be created for

each target when linked for the first time.

In this application note, the goal is to make a file that can

run in the AT90S2313 device. To do this, the release target

will be used. Select the “Release” target in the “Getting

started.prj” window as shown in Figure 2. Then select the

“Project->Options” menu. The window shown in Figure 3

will pop up.

Figure 2. Selecting Target Release

General Settings

In the “ General ” category in the “Options” dialog box, the

type of processor used is selected. It is necessary to

change two settings, “ Processor Configuration ” and “Mem-

ory Model ” . Please refer to Table 1 for the correct selection

for these choices for different AVR microcontrollers.

“Memory model tiny” uses a one byte data pointer, thus

allowing a maximum of 256 bytes data. “Memory model

small” uses a two byte data pointer, thus allowing up to 64

Kilobytes data. For the -v0 and -v2 “Processor Configura-

tion only the Memory model tiny” may be used.

In our example, the factory settings should be used, as

shown in Figure 3.

AVR030

AVR030

Figure 3. General Options Dialog

Table 1. Device Specific Settings

AVR Device

Processor Configuration

Memory Model

XCL file

AT90S2313

V0 (maximum 256 byte data, 8K code)

Tiny

2F128S.xcl

AT90S2323

V0 (max 256 byte data, 8K code)

Tiny

2F128S.xcl

AT90S2333

V0 (max 256 byte data, 8K code)

Tiny

2F128S.xcl

AT90S2343

V0 (max 256 byte data, 8K code)

Tiny

2F128S.xcl

AT90S4414

V1 (max 64 Kbyte data, 8K code)

Small

4F256S.xcl

4F64KS.xcl

AT90S4433

V0 (max 256 byte data, 8K code)

Tiny

4F128S.xcl

AT90S4434

V1 (max 64K byte data, 8K code)

Small

4F256S.xcl

AT90S8515

V1 (max 64K ‘byte data, 8K code)

Small

8F512S.xcl

8F64KS.xcl

AT90S8534

V1 (max 64K byte data, 8K code)

Small

8K256S.xcl

AT90S8535

V1 (max 64K byte data, 8K code)

Small

8F512S.xcl

Table 1. Device Specific Settings (Continued)

AVR Device

Processor Configuration

Memory Model

XCL file

ATmega103

V3 (max 64K byte data, 128K code)

Small

128F4KS.xcl

128F64KS.xcl

ATmega161

V3 (max 64K byte data, 128K code)

Small

16F1KS.xcl

16F64KS.xcl

ATmega603

V3 (max 64K byte data, 128K code)

Small

64F4KS.xcl

64F64KS.xcl

ICCA90 Settings

To get the dialog options for the specific settings of the

Compiler, click on the “ICCA90” line in the “Category” tab.

When using the memory model tiny , the factory settings are

OK.

If the memory model small is selected, it is necessary to

check the “ Writable strings, constants” checkbox. If this is

not done, variables defined as const will not be compiled

correctly. Figure 4 describes the settings when the memory

model small is selected.

The compiler may be optimized for code size or execution

speed. The type and level of optimization may be set in the

“ Optimization ” group in Figure 4. Only one type of optimiza-

tion may be specified for a single target. Note that if a high

level of optimization is used, the user may not be able to

debug the code. The code will be fully debuggable with

optimization level 3 (default for both types of optimization)

or lower.

Also note that it is strongly recommended that the “Embed

source” code checkbox in the “Debug ” tab is checked if a

debugging target, i.e. simulation or emulation, is used. This

will let you debug on the assembly level rather than on the

C language level. In AVR Studio you will also be able to

see exactly which assembly code is generated for the indi-

vidual C statements.

On the “List ” tab, the user is able to determine whether a

listing is generated, and the information included in this list-

ing. The “ Insert mnemonics ” option will, if checked, cause

the compiler to include the generated assembly lines in the

listing.

AVR030

AVR030

Figure 4. ICCA90 Option Settings

AA90 Settings

In the AA90 settings, the options for the assembler can be

changed. Since this application note does not contain any

parts written in assembly, the default settings can be left

unchanged.

XLINK Settings

The linker settings gives the linker instructions for how to

link together the object codes from the different Compiler,

Assembler and Library modules.

The first thing that needs to be selected is the format of the

output-file the linker is to create. In this application note, the

intention is to generate an “Intel Extended HEX” file which

is recognized by the STK200 starter kit.

Plik z chomika:

Inne pliki z tego folderu:

Inne foldery tego chomika: