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ADAS Head Up Application displaying navigation and situational
awareness information
system challenges, which may not
be obvious at first thought, vehicle
manufacturers
have
stringent
pollution standards to achieve and
therefore the weight and power
consumption of the overall solution
is important. The cost of the solution
is also critical due to the many tens
/ hundreds of thousands of vehicles
being produced. While security and
safety of the system is very critical
and governed by a number of
standards, using a SoC or FPGA can
help us address a number of these.
System Architecture
The development of an embedded
vision ADAS which monitors both
external and internal cameras can
be seen to be one of the more
challenging ADAS implementations.
This system needs to be able to
interface to several cameras located
around the vehicle, process the
images and provide the information
to the occupants. Many camera
solutions use point to point LVDS
wiring to transfer the data however,
this brings with it additional cost
and weight in the cabling required.
There are however alternative
approaches which are increasingly
gaining ground, this pushes some
functionality into the camera itself. If
the image output by the camera is
compressed and not the raw image,
then network based architectures
are possible. These networks could
be based around commonly used
automotive buses such as
MOST (Media Oriented Systems
Transport) - A high speed network
which can be implemented in either
optical or electrical physical layers
IDB-1394 - High speed network
implemented over an electrical
physical layer, this is implemented in
a daisy chained topology.
Ethernet AVB - Ethernet Audio
Visual Bridging provides the ability to
route image data and other data
around the vehicle as needed
Should we elect to use a network
the system architect must ensure
the necessary bandwidth is available
to transfer the image data between
the camera and ADAS core with the
required latency for its application.
The data generated by the ADAS
system may need to be shared with
other systems within the car for
instance adaptive cruise control,
or parking assist. Therefore, the
ADAS must be able to interface to
other commonly used automotive
interfaces like CAN or FlexRay.
At the architectural level the use of
an All Programmable Zynq® SoC
based approach provides several
advantages, if point to point wiring is
used to interface to the cameras the
camera receivers can be implemented
in the programmable logic prior to
the image processing chain. If an
All programmable SoC were to be
used the flexibility of the processor
system side would allow for the easy
inclusion of a CAN, Ethernet and other
protocols like FlexRay when combined
with logic in the programmable logic
and an external PHY if necessary. The
combination of dual core processors
and programmable logic allows for
a very low power per pixel, as the
system is very tightly integrated.
All Programmable SoC
Architecture
Where the SoC comes into its own is
the utilization of the Programmable
Logic (PL) to implement camera
interface and image processing
chain. While the Processing System
(PS) of the SoC can provide the
communication,
control
and
additional algorithmic processing
as required. The image processing
Automotive
Special Edition
New-Tech Magazine Europe l 47