iCC 2006 CAN in Automation
06-12
CAN configuration within Autosar
Dr.-Ing. R. Machauer, Bosch Engineering GmbH
AUTOSAR (AUTomotive Open System ARchitecture) aims to standardize interfaces
between software application functions and further between application functions and
basic software modules in ECUs (Electronic Control Unit). Independence from
underlying hardware and this modular software design allows exchangeability of
software functionalities amongst ECUs. The integration of functions from different
suppliers is established through a virtual function bus. The mapping to a certain
network topology (or to ECUs) is carried out after that step. In this paper configuration
of a CAN stack and related basic software modules in system architecture
development according to AUTOSAR is shown.
1 Introduction
Nowadays in automotive environment E/E
systems comprise of many ECUs, which
are connected via different bus systems
(CAN, LIN, FlexRay, MOST, proprietary
serial lines, etc.). In luxury cars the
number of ECUs may even reach 70. They
are classified into several system domains
like powertrain domain, chassis domain,
body domain, safety, infotainment, etc.
Inter domain communication is established
through gateways. The functional behavior
of an ECU is specified by the Original
Equipment Manufacturer (OEM), and
implemented by the hardware supplier.
Each ECU implements certain application
functions, which interact in some way with
other ECUs. It is a common approach, that
ECU hardware manufacturers also supply
application software with their ECU. With
this approach the system integration
medium is more or less the bus system
the ECU is connected to. With such a
large number of ECUs and interacting
functions error detection within a system is
a challenge for the system integrator. The
driving forces for AUTOSAR are [1]:
• Exchangeability of functional modules
(multiple suppliers)
• Manage increasing E/E complexity
associated with growth in functional
scope, which yields to improved quality
and reliability of E/E systems
• Higher flexibility for product
modification, upgrade and update
• Enable detection of errors in early
design phases
The AUTOSAR partnership was
established in summer 2003 [1]. First
release of AUTOSAR specification was
published in mid 2005. A second release
followed during the first quarter of 2006
[2]. In chapter 2 a short technical overview
of the AUTOSAR concept and its layer
model is given. In chapter 3 the Basic
Software (BSW) modules of
communication software(COM stack) and
the underlying layers are discussed in
detail.
2 AUTOSAR concept
The AUTOSAR software architecture
provides new design choices to software
engineers building distributed,
communication software systems. A key
aspect of this architecture is a design
abstraction called the AUTOSAR Virtual
Function Bus (VFB) (rf. Figure 1). VFB
allows the design of software systems
without reference to target hardware.
Hence during the design process the
mapping to a specific hardware is shifted
to later phase. The VFB is the collection of
all communication mechanisms (plus
some interfaces to the basic software) on
an abstract level.
An AUTOSAR system is build from of a
set of software components (SW-Cs).
Interaction among SW-Cs is accomplished
only through statically defined ports. Each
port is assigned an interface type, defining
the “way” of communication. Two
communication paradigms are provided for
SW-C ports, called sender-receiver and
client-server communication; Sender-