AVR-AUTOSAR

AVR-AUTOSAR is a real-time operating system for AVR microcontrollers based on the OSEK/VDX OS and AUTOSAR OS 4.4 standards.

AVR-AUTOSAR implements the scalability class 1 of AUTOSAR OS.

Motivation

The motivation for AVR-AUTOSAR was to create an easy-to-understand open-source implementation of AUTOSAR OS that can be run on widely available microprocessors.

The project was developed as part of a final thesis at the University of Applied Sciences Dortmund.

Quickstart

The project was created with the Atmel Studio 7 and the current AVR8-GCC-Toolchain on Windows. The solution and project files are included in the repository.

Configuration of the system is done in the AppCfg.h. The macros necessary are defined and documented in include/CfgGenMacros.h. The documentation from the current release can be found here. To generate the current documentation the provided doxyfile can be used.

The application code is placed in App.c.

The repository contains an test application for ATmega1284 devices which was used during development to test all the features of the operating system. It can be used as an example. Additionally multiple applications are provided for testing under AutosarOS/test.

Supported Microprocessors

The operating system was tested with the following devices:

• ATmega32
• ATmega328P
• ATmega128
• ATmega1284
• ATmega2560

Other microprocessors of the ATmega-family should work with minimal work required.

Tracing

During development a debugger-based system for tracing was used to record program flow.

The tracepoints set in Atmel Studio can be imported from the tracing.xml file. Note that the tracepoints for the ISRs will probably not load correctly as they are set on the user functions outside the operating system.

Additionally a data tracepoint can be set for errorInfo.id (write access) if error information is used. The following print message can be used to generate comments in the trace output which show what OS services are being called:

# {currentTask};{isISR} called $FUNCTION

The generated trace should look something like this:

#version 1.0
# INVALID_TASK;0 called OS_StartOS
898158796,Core_0,0,T,Idle,0,activate
898158921,Core_0,0,T,Task1,0,activate
898159328,Core_0,0,T,Task1,0,start
# Task1;0 called Events_SetEvent
# Task1;0 called Task_TerminateTask
898167984,Core_0,0,T,Task1,0,terminate
898169140,Core_0,0,T,Idle,0,start

The traces follow the "Better Trace Format" for OSEK and can be imported into Eclipse Trace Compass.

Note that the timestamps are generated on the host not the target! This means that absolute timings can't be trusted. Therefore this method should only be used to trace the program flow/order of execution.

Known limitations

• The system does not support relaxed linking (tail-call optimization). The -mrelax option which may be automatically activated by Atmel Studio when changing the device in the project settings MUST be disabled for correct operation of the OS.
• The system does not use ready queues for tasks. If multiple tasks with the same priority get activated they will be selected based on their order in the configuration not on the time of activation.
• The system does not support hardware-based counters (instead a timer that increments a software-based counter must be used).
• The constants for the alarm base are not automatically created and must either be created by the user or GetAlarmBase() must be used.