# WinAVR User Manual - 20080610

Eric B. Weddington
`<arcanum@users.sf.net>`

WinAVR is a suite of executable, open source software development tools for the Atmel AVR series of RISC microprocessors hosted on the Windows platform. It includes the GNU GCC compiler for C and C++.

## 1.0 What's New

Below is just a sample of what's new.

New from the WinAVR 20080512 release:

- Fixed a code generation bug with the XMEGA support regarding generation using RAMPZ and SREG.

- Fixed bugs in the ATmega32U4 I/O header file where a register was misnamed (DDIR2 changed to DIDR2), and fixed bit names for registers OCR0A and CLKPR.

## 2.0 WinAVR Installation

This section describes various information and notes about the installation of WinAVR.

### 2.1 Manifest

1. GNU Binutils 2.18

       Binary utilities for AVR target (including assembler, linker, etc.).

2. GNU Compiler Collection (GCC) 4.3.0

       C language and C++ language compiler for AVR target. There are
       caveats for using the C++ compiler. See the installed avr-libc
       User Manual in the <InstallDir>\doc directory.

3. avr-libc CVS snapshot (1.6 branch, post 1.6.2)

       C Standard Library for AVR.

4. AVR-Ada 0.5.2

       Run Time System for the Ada compiler.

       (Removed temporarily)

5. AVRDUDE 5.5

       avrdude is an open source programmer software that is user extensible.

6. GNU Debugger (GDB) / Insight 6.6

       GDB is a command-line debugger. Insight is GDB with a GUI!

7. AVaRICE 2.7

       avarice is a program for interfacing the Atmel JTAG ICE to GDB and users
       can debug their AVR. Use it in conjunction with GDB.

8. SimulAVR 0.1.2.5

       simulavr is used in conjunction with GDB to provide AVR simulation.

9. SRecord 1.38

       SRecord is a collection of powerful tools for manipulating EPROM load files.
       It reads and writes numerous EPROM file formats, and can perform many
       different manipulations.

10. MFile

        An automatic makefile generator for AVR GCC.

11. Programmers Notepad 2.0.7.667-devel

        Programming editor and IDE. This editor includes the Scintilla editor
        component.

12. LibUSB 0.1.12.1 and device drivers

        This is a USB library that is linked into AVRDUDE and AVaRICE to allow them
        to connect to the Atmel JTAG ICE mkII and the Atmel AVRISP mkII. Drivers
        for these devices are also included.

13. Cygwin DLLs

        Certain DLLs from the Cygwin project are required for specific included
        packages. See the Build Notes section for which packages require which DLL.

        NOTE: Not all executables require these Cygwin DLLs.

14. Many native Win32 GNU programs and utilities including make and bash.

15. Tofrodos 1.6

        A command-line text file line-ending convertor.

16. A Makefile Template for you to use in your projects.

17. Documentation for the various projects.

18. Source code patches used to build the various projects.

### 2.2 Layout

Listed below are some directories you might want to know about.

`<install>` = The directory where you installed WinAVR.

`<install>\bin`

  The AVR software development programs. This directory should be in your `PATH` environment variable. This includes:

  - GNU Binutils

  - GCC

  - avrdude

  - GNU Debugger (GDB)

  - Insight

  - AVaRICE

  - SimulAVR

  - SRecord

  - Various required DLLs

`<install>\utils\bin`

  A collection of Unix programs built for the Windows platform. The programs make and sh (bash) reside here. This directory should be in your PATH environment variable.

`<install>\avr\lib`

  avr-libc libraries, startup files, linker scripts, and stuff.

`<install>\avr\include`

  avr-libc header files. This is where, for example, #include <string.h> comes from.

`<install>\avr\include\avr`

  avr-libc header files specific to the AVR microprocessor. This is where, for example, #include <avr/io.h> comes from.

`<install>\lib`

  GCC libraries, other libraries,headers and stuff.

`<install>\libexec`

  GCC program components

`<install>\doc`

  Various documentation. Before asking, RTFM! :-)

`<install>\doc\avr-libc\examples`

  Example projects with source code. Have fun!

`<install>\sample`

  Sample makefile (see below). Batch files to use in compiling from AVR Studio 3.x (see below).

`<install>\pn`

  Programmers Notepad

`<install>\mfile`

  MFile

`<install>\source`

  Documentation on where to find the source code for the various projects and source code patches that were used to build the tools.

`<install>\utils\bin`

  Utility programs, mainly from Unix-land that are used in building the software, such as the shell (sh.exe), make.exe, and other programs called from a Makefile.

`<install>\utils\libusb\bin`

  LibUSB programs and drivers.

### 2.3 `PATH` Environment Variable

There are two directories in WinAVR that contain executable programs. If `<install>` is your install directory then these two directories are:

`<install>\bin`
`<install>\utils\bin`

The `<install>\bin` directory contains the software development toolset proper. This includes GNU binutils, GCC, and other programs.

The `<install>\utils\bin` contains many miscellaneous Unix or GNU programs that are built for Windows. This includes sh (bash) and make among a host of other things.

For your operating system to easily locate these directories, they must be put at the beginning of the `PATH` environment variable. WinAVR can do this automatically upon installation, if you selected this option. The reason for putting these directories at the beginning of the `PATH` environment variable is for the correct make program to be called. There have been reports from users that have Borland tools installed and the Borland make program is started rather than GNU make correctly started.

These programs are put into two seperate directories in case you want to use a different set of utility programs than the set that comes with WinAVR.

If you do not wish to use the utilities that comes with WinAVR, remove the `<install>\utils\bin` directory from your PATH environment variable.

For Windows 95 and 98 users, see the autoexec.bat file in the root drive where your OS is installed. This is usually in C:\.

For all other Windows users, the WinAVR installer modifies this registry key: `HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment\Path`

Important | On Windows NT/2K/XP you must have Administrator priviledges for the installer to automatically put these directories in your `PATH` environment variable.

### 2.4 Registry Keys

WinAVR installs a minimal amount of registry keys. These keys are installed to inform of the installation path, the uninstaller, and for GCC to find other parts of the compiler as needed. Below are the specific keys that are installed.

- Installation Location:: This registry key will be added to provide the location of the WinAVR installation:

      `HKEY_LOCAL_MACHINE\SOFTWARE\WinAVR\{VERSION}`

      with {VERSION} being replaced by the version number of WinAVR. Formerly,
      the key above without {VERSION} was equal to the install location.

- GCC Component Paths:: There are some keys that are installed that are used to help GCC find installed component programs:

      `HKEY_LOCAL_MACHINE\Software\Free Software Foundation\WinAVR-{VERSION}\GCC`

      `HKEY_LOCAL_MACHINE\Software\Free Software Foundation\WinAVR-{VERSION}\BINUTILS`

      `HKEY_LOCAL_MACHINE\Software\Free Software Foundation\WinAVR-{VERSION}\G++`

      with {VERSION} being replaced by the version number of WinAVR.
      Each of these keys points to the WinAVR install location for that version
      of WinAVR.

- PATH Environment Variable:: The registry key:

      `HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment\Path`

      may be modified (if selected at installation time) to add two directories to the
      PATH environment variable.

- Uninstaller:: There are several registry keys written under:

      `HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall\WinAVR-{VERSION}`

      with {VERSION} being replaced by the version number of WinAVR.
      These registry keys are used to register the uninstaller with Windows.

### 2.5 LibUSB-Win32

LibUSB-Win32 is a USB library that is linked into AVRDUDE and AVaRICE to allow them to connect to the Atmel JTAG ICE mkII and the Atmel AVRISP mkII. Drivers for these devices are also included. LibUSB is installed under:

`<install>\utils\libusb\bin`

The drivers for the JTAG ICE mkII and the AVRISP mkII are also located in the above directory.

To install the LibUSB-Win32 drivers (when AVR Studio is not installed): - Plug in your Atmel device (JTAG ICE mkII or AVRISP mkII). - When Windows asks to locate drivers for this device, select "Install from a list or specific location". Press Next. - Uncheck the checkbox, "Search removable media". - Check the checkbox "Include this location in the search" and select the location of the drivers in the directory specified above. Press Next. The driver will then be installed.

AVR Studio can install and use the USB drivers from Jungo (which is included as part of the AVR Studio installation). However, the Jungo drivers and the LibUSB-Win32 drivers are mutually exclusive; if one set is installed the other set will not work.

You can uninstall the driver by plugging in the device (and making sure it is powered on), use the Device Manager to find and select the device (under Jungo or LibUSB-Win32, depending on which driver is installed), right click and select "Uninstall". Then, install the other driver according to the correct procedures.

LibUSB also has a "filter" driver that is available, however, using this is not recommended by the LibUSB author.

## 3.0 Toolset Background

WinAVR is a collection of executable software development tools for the Atmel AVR processor hosted on Windows.

These software development tools include:

- Compilers

- Assembler

- Linker

- Librarian

- File converter

- Other file utilities

- C Library

- Programmer software

- Debugger

- In-Circuit Emulator software

- Editor / IDE

- Many support utilities

### 3.1 The Toolset and Open Source

Each of the tools included in WinAVR is Open Source and/or Free Software. Each tool has it's own project, usually hosted on SourceForge or Savannah, with their own project maintainers and developers who all volunteer their time and energy to creating these tools. Look in the Links section below to find out the websites of each of these projects.

Especially note many of these programs come from the Unix and Linux platforms. These programs have been ported to the Windows platform but generally behave for a Unix-like environment. If you are not used to a Unix-like environment it can possibly be frustrating. Read as much documentation as you can. Look at examples. Search the Internet. Many links are also provided in this manual.

Also remember that this software is updated and improved continually by many people who volunteer their precious time to provide some of the best software for absolutely no cost or obligation to you. Volunteers are always welcome in furthering any of these projects!

### 3.2 Compiler

The compiler in WinAVR is the GNU Compiler Collection, or GCC. This compiler is incredibly flexible and can be hosted on many platforms, it can target many different different processors / operating systems (back-ends), and can be configured for multiple different languages (front-ends).

The GCC included in WinAVR is targeted for the AVR processor, is built to execute on the Windows platform, and is configured to compile C, or C++.

Caution | There are caveats on using C++. See the avr-libc FAQ.

Because this GCC is targeted for the AVR, the main executable that is created is prefixed with the target name: `avr-gcc.exe`. It is also referred to as AVR GCC.

`avr-gcc` is just a "driver" program only. The compiler itself is called `cc1.exe` for C, or `cc1plus.exe` for C++. Also, the preprocessor `cpp.exe` will usually automatically be prepended with the target name: `avr-cpp.exe`. The actual set of component programs called is usually derived from the suffix of each source code file being processed.

GCC compiles a high-level computer language into assembly, and that is all. It cannot work alone. GCC is coupled with another project, GNU Binutils, which provides the assembler, linker, librarian and more. Since GCC is just a "driver" program, it can automatically call the assembler and linker directly to build the final program.

### 3.3 Assembler, Linker, Librarian and More

GNU Binutils is a collection of binary utilities. This also includes the assembler, as. Sometimes you will see it referenced as GNU as or gas. Binutils includes the linker, ld; the librarian or archiver, ar. There are many other programs included that provide various functionality.

Note that while the assembler uses the same mnemonics as proposed by Atmel, the "glue" (pseudo-ops, operators, expression syntax) is derived from the common assembler syntax used in Unix assemblers, so it is not directly compatible to Atmel assembler source files.

Binutils is configured for the AVR target and each of the programs is prefixed with the target name. So you have programs such as:

`avr-as`

  The Assembler.

`avr-ld`

  The Linker.

`avr-ar`

  Create, modify, and extract from archives (libraries).

`avr-ranlib`

  Generate index to archive (library) contents.

`avr-objcopy`

  Copy and translate object files.

`avr-objdump`

  Display information from object files including disassembly.

`avr-size`

  List section sizes and total size.

`avr-nm`

  List symbols from object files.

`avr-strings`

  List printable strings from files.

`avr-strip`

  Discard symbols.

`avr-readelf`

  Display the contents of ELF format files.

`avr-addr2line`

  Convert addresses to file and line.

`avr-c++filt`

  Filter to demangle encoded C++ symbols.

See the binutils user manual for more information on what each program can do.

### 3.4 C Library

avr-libc is the Standard C Library for AVR GCC. It contains many of the standard C routines, and many non-standard routines that are specific and useful for the AVR processor.

Note | The actual library is currently split into two main parts, libc.a and libm.a, where the latter contains mathematical functions (everything mentioned in <math.h>, and a bit more). Thus it is a good idea to always include the `-lm` linker option. The WinAVR Makefile Template automatically includes the `-lm` linker option. Also, there are additional libraries which allow a customization of the printf and scanf function families.

avr-libc also contains the most documentation on how to use (and build) the entire toolset, including code examples. The avr-libc user manual also contains the FAQ on using the toolset.

### 3.5 Making Your Software

There is one program that brings all of this together. This program is `GNU make`. The `make` program reads and interprets a makefile. A makefile is a text file that you write that lists and controls how something is made. It is most often used to control how software is made.

Each of these programs are Command Line Interface (CLI) tools. They are controlled by parameters or switches that are added to the command line. Or, in the case of make, by text files that are written and used as input.

Most commercial software development toolsets have an Integrated Development Environment (IDE). This consists of a graphical user-interface (GUI) that contains a programming editor and graphical front-ends to compiler, assembler, linker, standard C library, and librarian programs. These front-ends consist of dialog boxes which allow you to set build options and a way of creating a list of files that are in a "project". These graphical front-ends hide and encapsulate the real command-line compiler, assembler, linker, and standard library that are in the background of any software development toolset.

WinAVR is a collection of open-source, software development tools from various projects. WinAVR does not have a complete graphical IDE like a commerical toolset, yet. Because of this, learning to build software under GCC means that it would be best to learn how to use the `make` program and learn how to write makefiles. Learn the common flags that are used to control GCC which in turn can control `gas` and `ld`. You can learn a lot by looking at the Makefile Template that comes with WinAVR and looking up all the programs and flags in the included user manuals.

### 3.6 Programming

After creating your software, you'll want to program your device. You can do this by using the program `avrdude` which can interface with various hardware devices to program your processor.

`avrdude` is a very flexible package. All the information about AVR processors and various hardware programmers is stored in a text database. This database can be modified by any user to add new hardware or to add an AVR processor if it is not already listed.

### 3.7 Debugging

Debugging encompasses both simulation and emulation. Both are available in WinAVR.

The GNU Debugger (`GDB`) is the main package that can be used for general debugging. `GDB` is a command-line program only. `Insight` is GDB plus a GUI written in Tcl/Tk. Both `GDB` and `Insight` are configured for the AVR and the main executables are prefixed with the target name: `avr-gdb`, and `avr-insight`. There is now also a "text mode" GUI for GDB: `avr-gdbtui`.

To do emulation with the JTAG ICE, GDB / Insight requires a "helper" program called `avarice` which is also included.

To do simulation, GDB / Insight requires a different "helper" program called `simulavr` which is also included.

There are also alternatives for simulation. Atmel offers a free package called `AVR Studio` which can also do simulation. The latest version of `AVR Studio` is 4.13. Note that `AVR Studio` is currently free to the public, but it is not Open Source.

See the section, 5.0 Debugging, Simulating, and Emulating, for detailed information on debugging.

## 4.0 Setting Up a Project

### 4.1 Where's the GUI / IDE?

You won't find a typical GUI / IDE like you might be used to with other commercial cross-compilers, or like native compilers on Windows. Each of the tools in WinAVR are from their own projects. In this case, an editor or IDE is just another component in the toolset. And, everybody has their own favourite they want to use. WinAVR allows flexibility.

WinAVR comes with an editor / IDE called Programmers Notepad. This is an Open Source editor with some IDE capabilites. Because the compiler and associated utilities are all command-line driven, you are free to use whatever editor / IDE you want to provided it can call command-line programs. See below for more information on Programmers Notepad.

There is current work going on to continually improve the IDE capabilities of Programmers Notepad. Let us know if you're interested in volunteering to help on these projects.

### 4.2 Programmers Notepad

Programmers Notepad (PN) is an Open Source editor with some IDE features. Version 2.x is is a complete rewrite of version 1. Many new features are still being added.

PN contains the Open Source Scintilla editor component as the basis for its editor.

PN can call any command-line tool and capture it's output. This is ideal for calling the make utility, which executes your makefile, which in turn calls the compiler, linker, and other utilities used to build your software. PN will then capture the output and display it in a window. You can also click on any GCC warning or error and PN will automatically open the file and go to the line where the warning or error occurred.

To set up tools, go to the Tools menu up top, select Options, then select Tools on the left side menu. The best Scheme to add tools is under "(None - Global Tools)". After you add your tool, it will appear in the Main Menu under Tools.

### 4.3 Make, Makefiles, and the Makefile Template

make is a program that is widely used to build software. make reads and executes makefiles, which are descriptions of how to build something. Makefiles typical do things such as group files together, set lists of compiler and linker flags, list rules of how to compile source code to object code, how to link object files, how to convert files from one type to another, and many other things.

When you set up your project, add a makefile to control how to build your software. When you use Programmers Notepad, or other IDE, set it up to call make and have it execute your project's makefile.

Three Makefile Templates are included in WinAVR, which provides a lot of functionality already written for you. There is the standard Makefile Template (Makefile) that has always been included with WinAVR. And there are two new Makefile Templates, one to generate a library instead of an application (Makefile.lib) and another Makefile Template that enables whole program optimization (Makefile.wpo). You can can copy any of these templates to your project's directory and easily modify it to fit your project. These Makefile Templates can be found in the `<install>\sample` directory. Copy any of these templates and rename them to `Makefile`.

WinAVR also includes the MFile utility. MFile is a automatic makefile generator for AVR GCC written in Tcl/Tk and can run on various platforms including Windows, FreeBSD, Linux, etc. You can use this utility to help you quickly generate a makefile for your project based on some simple menu input. MFile for the Windows platform uses the WinAVR Makefile Template for it's template.

Note | I HIGHLY RECOMMEND THAT YOU BECOME FAMILIAR WITH THE MAKE PROGRAM AND WRITING MAKEFILES! PLEASE READ THE MAKE USER MANUAL!

For more information on the make program and writing makefiles, see the make user manual that is included or see Links below for GNU Manuals Online.

## 5.0 Debugging, Simulating, and Emulating

Note | The term "debugging" is a generic term and can mean either simulation or emulation below.

There are several different ways to go about debugging, simulating, and emulating. Each solution has their own requirements and may involve various tradeoffs.

There are open source applications that can be used for simulation and emulation, and they are included with WinAVR. Use `GDB` or `Insight`, with the `simulavr` back-end for simulating, or with the `avarice` back-end to emulate using the Atmel JTAG ICE.

There is a free application from Atmel that can be used for simulation or emulation: AVR Studio. The latest version as of this writing is 4.11. AVR Studio can be downloaded from the Atmel web site.

There are also a number of commercial simulators, such as VMLab or Proteus VSM.

In general, debugging is dependent upon:

1. The application used to debug.

2. The file format used.

3. The type of debugging information generated in the object code.

Many times the application that is being used, determines the file format, and the type of debugging information that needs to be generated.

This version of the compiler can generate both DWARF2 and stabs debugging information.

Note | The compiler will currently default to generating DWARF2 debugging info.

If you are using the WinAVR Makefile Template, or using MFile, there is a line in the makefile that controls the type of debug information that is generated:

    DEBUG = dwarf-2

To generate stabs information change this line to:

    DEBUG = stabs

Tip | MFile can change this setting automatically through a menu option.

This line in the makefile changes the `-g` compiler switch that is sent to GCC. See the GCC user manual for more information.

The compiler will build your software and automatically output an ELF file.

### 5.1 GDB/Insight + simulavr or avarice

The GNU Debugger (GDB) can be used, with other programs, to simulate or emulate your AVR program. Insight is GDB with a GUI (written in Tcl/Tk). Insight also has a console window which provides the traditional command-line interface to GDB. The terms GDB and Insight will be used interchangably.

Use `avarice` with GDB for use with your JTAG In-Circuit Emulator (ICE).

Use `simulavr` with GDB for simulation.

See each of the package's documentation for more information on usage.

Requirements

File Format: ELF
Debugging Information: DWARF-2 (preferred) or stabs

Tip | There is a tutorial on how to use GDB and avarice at the WinAVR web site.

Tip | If you use `avarice`, when you specify a serial port to use with the —jtag flag, you must specify it in the form of:

    --jtag /dev/comX

where X is the COM port number you are using. This is due to the fact that avarice is linked to the Cygwin DLL, which requires a Unix-type format for the COM port number.

### 5.2 AVR Studio

AVR Studio 4.10 and above has a new parser component that can read ELF files natively. These ELF files must contain DWARF2 debugging information.

Requirements (for AVR Studio version 4.10 and greater)

File Format: ELF
Debugging Information: DWARF-2

### 5.3 Commercial Simulators

Certain commercial simulators have more requirements to use their products. Namely, you must compile your software with the `stabs` debugging information, and you must convert your ELF file to either the COFF format or to the Atmel Extended COFF format.

Requirements (dependent upon application used)

File Format: COFF / Atmel Extended COFF
Debugging Information: stabs

The GNU Binutils program objcopy (avr-objcopy) has been patched where it can now convert from ELF to either of these formats. Note that the converter is a beta release.

The usage of avr-objcopy to convert ELF/stabs debugging information into AVR COFF debugging information is (long lines wrapped with backslashes):

    avr-objcopy \
            --debugging \
            -O $(FORMAT) \
            --change-section-address .data-0x800000 \
            --change-section-address .bss-0x800000 \
            --change-section-address .noinit-0x800000 \
            --change-section-address .eeprom-0x810000 \
            $(filename).elf $(filename).cof

where `$(FORMAT)` should either be `coff-avr` (COFF format that matches the older Atmel AVR COFF documentation, as understood by AVR Studio 3, early versions of AVR Studio 4, and also by VMLab), or `coff-ext-avr` (current AVR Extended COFF specification, as understood by AVR Studio 4.07+; adds long filenames and structure debugging).

There might be some warnings when you run the above, like

    Warning: file {standard input} not found in symbol table, ignoring
    Warning: ignoring function __vectors() outside any compilation unit
    Warning: ignoring function __bad_interrupt() outside any compilation unit

Perhaps more of them if your avr-libc has been installed with debugging symbols (the default WinAVR installation strips debugging symbols from the installed library files). There should be no other warning normally.

Note | The avr-objcopy usage describe above is in the Makefile Template that is included with WinAVR and in the MFile template. You should only have to call make coff to convert to AVR COFF, or call make extcoff to convert to AVR Extended COFF.

As Atmel has now moved towards the ELF file format with DWARF-2 debugging information, the (E)COFF conversion is deprecated. Thus, there is currently no ongoing development on the COFF converter. There are a few known bugs in it, in particular it is known that using forward struct references can crash the converter. Unfortunately, fixing this bug would be close to a whole rewrite of it. As a workaround, just avoid forward struct references.

Instead of writing:

    typedef struct foo *foo_p;
    struct foo {
        foo_p next;
        int something;
    };

reorder it to:

    struct foo {
        struct foo *next;
        int something;
    };
    typedef struct foo *foo_p;

That strategy is known to work around that particular bug.

## 6.0 Useful Additions

### 6.1 Operating Systems

While an Operating System, or RTOS, isn't necessary to write software for the AVR, there may be times when it is desirable. Below, are some links for free or open source operating systems / kernels for the AVR. Note that this may not be a complete list.

AvrX

  AvrX is a Real-Time Multitasking Kernel.

EtherNut - Nut/OS

  Ethernut is an Open Source Hardware and Software Project for building Embedded Ethernet Devices. It contains Nut/OS which is an intentionally simple RTOS for the ATmega128, which provides a minimum of services to run Nut/Net, the TCP/IP stack.

FreeRTOS

  FreeRTOS is a portable, open source, mini Real Time Scheduler (or mini RTOS kernel).

TinyOS

  TinyOS is a component-based runtime environment designed to provide support for deeply embedded systems which require concurrency intensive operations while constrained by minimal hardware resources.

Contiki

  Contiki is an Internet-enabled operating system and desktop environment for a number of smallish systems.

XMK - eXtreme Minimal Kernel

  XMK is a preemptive multitasking scheduler/kernel for 8bit microcontrollers. Its goal is to provide a bare bones RTOS with a small enough footprint (RAM+ROM) to run on 8bit microcontrollers.

pico OS

  pico OS is a highly configurable and very fast real time operating system (RTOS). It targets a wide range of architectures, from very small 8 bit processors and microcontrollers up to very huge platforms. An AVR port is available.

uSmartX

  uSmartX is a non-preemptive, multitasking, priority based RTOS. It features mechanisms for inter-task communication and basic task and time control functions.

Super Simple Tasker (SST)

  This is an implementation of a lightweight scheduler so called "Super Simple Tasker" - SST. The idea is taken from the Robert Ward's article - "Practical Real-Time Techniques" http://www.quantum-leaps.com/resources/Ward03.pdf. The SST allows to significantly reduce needs for precious RAM and ROM and still allows to keep a real time characteristic of the scheduler (e.g. tasks prioritization and preemption).

ChibiOS/RT

  ChibiOS/RT is a compact and fast RTOS designed for embedded applications. It offers threads, mutexes, semaphores, messages, events, timers, flexible I/O with timeout capability.

### 6.2 Other

Here are some links to free or open source components that may be useful.

uIP - TCP/IP Stack for Embedded Microcontrollers

  uIP is an implementation of the TCP/IP protocol stack intended for small 8-bit and 16-bit microcontrollers. It provides the necessary protocols for Internet communication, with a very small code footprint and RAM requirements - the uIP code size is on the order of a few kilobytes and RAM usage is on the order of a few hundred bytes.

LibTomCrypt

  LibTomCrypt is a fairly comprehensive, modular and portable cryptographic toolkit that provides developers with a vast array of well known published block ciphers, one-way hash functions, chaining modes, pseudo-random number generators, public key cryptography and a plethora of other routines. LibTomCrypt has been designed from the ground up to be very simple to use. It has a modular and standard API that allows new ciphers, hashes and PRNGs to be added or removed without change to the overall end application. It features easy to use functions and a complete user manual which has many source snippet examples. LibTomCrypt is free for all purposes under the public domain. This includes commercial use, redistribution and even branching. [Editor's Note: This package was reported to have been able to build for AVR, but it's not completely verified.]

Protothreads

  Protothreads are extremely lightweight stackless threads designed for severely memory constrained systems such as small embedded systems or sensor network nodes. Protothreads provide linear code execution for event-driven systems implemented in C. Protothreads can be used with or without an underlying operating system.

## 7.0 Finding Help

WinAVR is a packaged collection of software devlopment tools built from open source projects.

There is a large community of people who use these tools. There are a number of these people who volunteer their time to help other people with problems or questions. And then there are other people who also volunteer their time to contribute to these open source projects.

The main places to find help is the Documenation and Online Sources. Please try and find the answer in the documentation first before asking for help online.

Tip | If you need to ask for help online, please read this first: How To Ask Questions The Smart Way

### 7.1 Documentation

The first and best place to find help is in the documentation! WinAVR includes the user manuals for many of the software tools that are shipped in the package.

The documentation for any particular package may come in different formats depending upon what is available from that package and available space in the WinAVR installation. The different documentation formats that you'll find in WinAVR are:

1. HTML - Hyper Text Markup Language. Requires a web browser to view.

2. PDF - Portable Document Format. Requires a PDF viewer such as Acrobat.

Additionally many user manuals can also be found online, especially packages that are part of the GNU project. You can find links to many of these in the Links section below.

For packages that have HTML, and PDF documentation, look in your `<install>\doc` directory.

WinAVR installs on your desktop two shortcuts. One is to the HTML documentation on avr-libc that is installed locally. The other shortcut is to the GNU Manuals online (which requires Internet connection).

### 7.2 Online Sources

I'll say it again:

Please try and find the answer in the documentation first before asking for help online.

Tip | If you need to ask for help online, please read this first: How To Ask Questions The Smart Way

Help for the AVR software development toolset (and specifically AVR GCC) can be found at:

AVR Freaks

  All AVR, all the time! This site has several forums including a general AVR Forum and an AVR GCC Forum specifically for discussion of the GCC compiler for the AVR. They also have an Academy which contains user's projects. This gives you access to a lot of sample code, libraries, and various AVR projects.

avr-gcc mailing list

  The avr-gcc list is intended as a forum for dicussion about the following: Bugs, Programming technique, Installation and distributions, Hints and tips, Other avr-gcc related stuff. Note that all of the developers of the toolset are subscribed to this list!

Mikrocontroller.net

  For native German speakers. They have a forum for the AVR GCC compiler.

Help for other projects and tools included in WinAVR can usually be found at the individual project's web page which usually includes links to their mailing lists.

If you need help, do not contact the WinAVR developers personally! Use these web sites and mailing lists first!

## 8.0 Toolset Bugs

You can fill out a relevant tracker on the WinAVR SourceForge project page, if you have one of the following:

- a bug in the packaging

- a bug in the installation

- any suggestions for a new tool to be added

- any suggestions for improvements to the overall package

Important | IF THERE ARE BUGS IN THE SOFTWARE TOOLS THEMSELVES, THE MAINTAINERS OF THE INDIVIDUAL SOFTWARE PROJECTS SHOULD BE NOTIFIED IN THE APPROPRIATE MANNER, NOT ME, OR THE WINAVR PROJECT!!!!

Generally, if you encounter a bug with a library routine or a bug with a specifc AVR processor or header file, notify the avr-libc project first (see Links below). They will let you know if the bug is truly in the avr-libc project, or if it should be passed on to the GCC project. If the bug is in GCC, go to their web page (see Links below) on how to report bugs to GCC.

For bugs with Programmer's Notepad 2, see it's SourceForge web site (see Links) to issue a Bug Tracker, or email it's author (see Credits).

For bugs with avrdude, see it's Project page (see Links).

For bugs with simulavr, see it's Project page (see Links).

For bugs with avarice, see it's Project page (see Links).

For bugs with GDB, see it's web page (see Links).

For bugs with Insight, see it's web page (see Links).

For bugs with SRecord, see it's Home page (see Links).

## 9.0 WinAVR FAQ

This FAQ is specific to the WinAVR package and installation. For a programming issues, see the avr-libc FAQ in the avr-libc documentation included in the WinAVR package or the avr-libc user manual online.

#1) When I run a program, why do I get the error "You have multiple copies of cygwin1.dll on your system."?

Certain packages in WinAVR are built with Cygwin and are linked to their emulation library: cygwin1.dll. If you also have Cygwin installed seperately, these programs will find the cygwin1.dll that is shipped and included with WinAVR, and will also find the cygwin1.dll in your Cygwin installation. If these versions are different, you will get this error.

WinAVR must ship the cygwin1.dll file to support it's packages, as most people do not have Cygwin installed on their system and it's not fair to ask people to install such a huge package as a prerequisite.

Unfortunately, the Cygwin FAQ says that the only way around this is to remove other copies of cygwin1.dll. This would mean either uninstalling Cygwin so the WinAVR programs work, or perhaps renaming the cygwin1.dll found in the `<install>\bin` directory so the WinAVR programs will use the cygwin1.dll that is in the Cygwin installation. However, if you do the latter, note that the version of cygwin1.dll you have in your Cygwin installation is probably different than the version of cygwin1.dll that was used to build the WinAVR programs. In this case, use at your own risk.

#2) I have any of the following warnings when I create a COFF file, what should I do?

    Warning: file {standard input} not found in symbol table, ignoring
    Warning: ignoring function __vectors() outside any compilation unit
    Warning: ignoring function __bad_interrupt() outside any compilation unit
    Discarding local symbol outside any compilation unit: .__do_copy_data_start
    Discarding local symbol outside any compilation unit: .__do_copy_data_loop

Nothing. These warnings can be ignored.

#3) I use WinAVR with AVR Studio. I get an error when avr-objcopy is creating the load file for the EEPROM. It says there are no sections to be copied.

avr-objcopy is a part of GNU Binutils. In GNU Binutils 2.17 or later, the objcopy program was changed to return an error when there are no sections to be copied. This is different than previous versions of the objcopy program. This is not really an error, as it is ok if there are no sections to be copied.

The Makefile has to be aware of this new behaviour and to not accept this as a real error. Use the WinAVR Makefile Template as the basis of your Makefile, or use AVR Studio 4.13 (soon to be released, if not already) which has changed how it generates its internal Makefile on GCC projects to correctly account for this.

## 10.0 WinAVR Project

### 10.1 Build Notes

The contained packages are built either in the Cygwin environment, or the MinGW environment. Some, but not all, packages are dependendent upon one or more Cygwin DLLs, which are included in WinAVR.

1. GNU Binutils: MinGW.

2. GCC: MinGW.

3. avr-libc: MinGW.

4. avrdude: Cygwin.

5. GDB/Insight: MinGW.

6. AVaRICE: Cygwin. Requires: cygwin1.dll,

7. SimulAVR: Cygwin. Requires: cygwin1.dll.

8. SRecord: MinGW.

DLL Versions:

- cygwin1.dll: 1.5.23-2

Programmer's Notepad 2 was built by the author, Simon Steele (see Credits). Tofrodos was built by the author, Christopher Heng (see Credits).

### 10.2 Credits

Thank you to everyone who uses WinAVR!

- WinAVR software devleopment toolset distribution built by

Eric B. Weddington
email

One person cannot do all of this alone. There are many, many people involved in making this package what it is. I am deeply indebted to those people. Below is an attempt at a list of credits. Any omissions are my fault and corrections are solicited.

- Very Special Thanks to Joerg Wunsch for helping this project in innummerable ways including writing the AVR COFF patch for binutils; patches for GCC to help with debugging and binary constants; being the resident guru on AVR Freaks; writing portions of this manual; reviewing all of my wacky ideas; building SRecord; getting me in contact with the right people at the right time ;-) ; spending the time to take me on a beautiful hike near his home town; and for tolerating me over the years. I don't know why he does it, but I am eternally grateful. :-)

- Very Special Thanks to major contributers to the AVR toolset: Denis Chertykov, Marek Michalkiewicz, Theodore (Ted) A. Roth, Joerg Wunsch, Michael Stumpf, Reiner Patommel, Brian S. Dean, Scott Finneran, David Gay, Jason Kyle, Bjoern Haase, Anatoly Sokolov, Dmitry Xmelkov.

- Thanks to Brian Dessent and Dave Murphy (wintermute) for help in getting the toolchain to work on Windows Vista. Thanks to Dave Murphy for the patch for Insight.

- Very Special Thanks to Bjoern Haase for taking the time and effort to put together the patches to add support for the ATmega256x devices and for the last minute phone call with Joerg to resolve the last problem!

- Very Special Thanks to Colin O'Flynn for writing a tutorial on how to install and configure WinAVR, writing a tutorial on how to use Insight, for testing WinAVR, all around assistance, and helping on avrdude.

- Very Special Thanks to Torleif Sandnes for all his help in getting WinAVR to work in AVR Studio in all its various ways.

- Thanks to SourceForge for hosting the WinAVR project.

- Very Special Thanks to Simon Steele for permission to include Programmers Notepad in WinAVR. Programmer's Notepad is written and built by Simon Steele.

- Native Win32 Unix programs from:

  - Karl M. Syring <http://www.weihenstephan.de/~syring/win32/UnxUtils.html>

  - http://www.morpheus.demon.co.uk/ (bison and flex)

  - MinGW

- Tofrodos 1.6 is written and built by Chistopher Heng

- Thanks to the following people for additional material for the Makefile Template: Tim Henigan, Peter Fleury, Joerg Wunsch, Reiner Patommel, Sander Pool, Frederik Rouleau, Markus Pfaff, and Carlos Lamas.

- Special Thanks to Markus Assfalg for all his input in doing AVR COFF pre-alpha tests and to Svenn-Ivar Svendsen from Atmel Norway, who willingly answered questions regarding Atmel's COFF specs.

- Very Special Thanks to Torleif Sandness of Atmel, the principal developer of Atmel's ELF parser for AVR Studio, for really pioneering that area.

- Thanks to members of the AVR COFF Alpha Testing team, which include: Wallace White, Markus Assfalg, Volkmar Dierkes, Marc Wetzel, Andrew Ghali, Omer Sinan KAYA, Eric Weddington.

- Thanks to Atmel and to Advanced Micro Tools (AMTools), makers of the VMLAB debugger tool, for assistance in the endeavour of writing the AVR COFF patch.

- Special thanks to Nick Moore for designing the WinAVR logos!

- Special thanks to Brian Brill for helping to move around some large files for the first release; to Ted Roth for hosting the first WinAVR release on the avr-libc web site.

- Very Special Thanks to Ted Roth and Joerg Wunsch for putting up with me when I was starting out.

- And a Very Special Thank You to Atmel Corporation.

### 10.3 TODO / Open Projects

- avarice needs a native Win32 port (no dependency on Cygwin DLL).

- simulavr needs a native Win32 port.

- Much more…

Stay tuned…. ;-)

## 11.0 Links

WinAVR Project
WinAVR Home Page

SourceForge

AVR Freaks

avr-gcc mailing list
avr-chat mailing list

Atmel `Atmel AVR microcontrollers` Atmel's AVR Tools and Software
Atmel Norway's AVR Tools Beta Site

GNU Project

GNU Manuals Online

GNU Binutils

GNU Compiler Collection (GCC)

GCC Manuals Online

avr-libc

avrdude

avrdude-gui

uisp

GNU Debugger (GDB)

Insight

avarice

simulavr

AVR-Ada

MFile

Programmers Notepad
Scintilla

SRecord

Splint

LibUSB-Win32

dwarfdump

stacktool

AvrX

EtherNut - Nut/OS

FreeRTOS

TinyOS

Contiki

XMK - eXtreme Minimal Kernel

Pico OS

uSmartX

LibTomCrypt

uIP - TCP/IP Stack for Embedded Microcontrollers

Protothreads

Tofrodos

GNU Make

MinGW

Cygwin

Free ICE

Pymite

NanoVM

Jargon