Automotive Embedded System
SEE THE REFERENCES
Introduction
 The details of embedded electronics in automotive
systems is depicted very nicely in this picture from
Clemson University:
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http://www.cvel.clemson.edu/auto/systems/autosystems.html
 Lets go through a fine introduction to automotive
embedded system by Hiro Takada
 Steve Corrigan. Introduction to the Controller Area
Network (CAN), Texas Instruments. Industrial
interface: July 2008
Internet of Things
 Devising sensors and algorithms to handle the front-
and back-ends of the IoT are the easy part.
 Securing/protecting the IoT from the hackers
(malicious attacks) and inadvertent
misuse/interference are critical issues to be
addressed.
 Yet to be explored: The middleware between the
sensors in things at the edge of the internet, and the
data collection and analysis on the cloud.
Just hot off the press
 From the Design Automation Conference 2014:
http://www.embedded.com/print/4430404
Clemson’s View of Automotive Electronics System
http://www.cvel.clemson.edu/auto/systems/auto-systems.html
CAN Bus
 Controller Area Network (CAN)
 Reference: SLOA101A–August 2002–Revised July 2008
Introduction to the Controller Area Network (CAN)
 The CAN bus was developed by BOSCH as a multi-master,
message broadcast system that specifies a maximum signaling
rate of 1 megabit per second (bps).
 Unlike a traditional network such as USB or Ethernet, CAN
does not send large blocks of data point-to-point from node A
to node B under the supervision of a central bus master.
 In a CAN network, many short messages like temperature or
RPM are broadcast to the entire network, which provides for
data consistency in every node of the system.
CAN Bus (contd.)
 The specification calls for high immunity to electrical
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interference and the ability to self-diagnose and
repair data errors.
These features have led to CAN’s popularity in a
variety of industries including building automation,
medical, and manufacturing.
See figure 1 for architecture: this is a good example
for the architecture of your term project.
See figure 2 for standard CAN message format
See figure 3 extended CAN message format
Distinctive features of CAN Bus
 Inverted (voltage) logic
 The allocation of priority to messages in the identifier is a
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feature of CAN that makes it particularly attractive for use
within a real-time control environment.
Automatic arbitration based on the priority, in case more than
one transmission is encountered.
Details of the CAN bus figure 6: CAN Device
(DSP/Microcontroller), CAN controller, CAN Transceiver,
CAN Bus lines (CANL…CANH)
The High-Speed ISO 11898 Standard specifications are given
for a maximum signaling rate of 1 Mbps with a bus length of
40 m with a maximum of 30 nodes.
Different types of messages.
Payload semantics: advantage.
Conclusion as given in the report
 CAN is ideally suited in applications requiring a large number
of short messages with high reliability in rugged operating
environments. Because CAN is message based and not
address based, it is especially well suited when data is needed
by more than one location and system-wide data consistency
is mandatory.
 Fault confinement is also a major benefit of CAN. Faulty
nodes are automatically dropped from the bus, which
prevents any single node from bringing a network down, and
ensures that bandwidth is always available for critical
message transmission. This error containment also allows
nodes to be added to a bus while the system is in operation,
otherwise known as hot-plugging.
 Has wide practical application in a number of industries other
than automobile.
Hmm.. How about scalability?
How about bandwidth for communications?
How about different types for different systems? Kind of hybrid?
Flexray?
Lin?
MOST?
CAN-FD?
Ethernet?
See this paper… lets read and understand..
D. Thiele, P. Axer, R. Ernst, J. Diemer, and K. Richter, “Cooperating
on real-time capable ethernet architecture in vehicles,” in Proc. Of
Internationaler Kongress Elektronik im Fahrzeug, oct 2013.
https://ece.uwaterloo.ca/~sfischme/rate/S1P2.pdf
 (Afterall, the ECUs are moving an automobile towards a computign
system, why not use the bus that is so sucessful in general computer
communications?)
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Summary
 We had a high-level view of the automotive
embedded system.
 We will further explore these units in depth in the
next week’s lecture and as per need by the various
projects chosen by you.
 We will also look into to the “manager” AUTOSAR
that brings all things together.