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Challenge
To design electronic units for road vehicles is a challenge, since a competitive bill of material price is crucial. Yet we have to fulfill demands that are really tough. For instance:
Operational temperature range at least -40 to +85(125)C.
Robustness to an exceptional harsh electrical environment.
EMC compliance to very restrictive standards.
Additional requirements might be for instance very sparse power consumption in sleep mode or built in energy reserve up to 250 ms for safety critical units (such as airbag control units).
The ECUs in a car are often connected together by one or several data buses. The most common buses in a car are:
CAN – (Controller Area Network) is a multidrop bus working on a twisted pair at speeds up to 1 Mbps. It is used for communication between non safety critical nodes.
LIN – (Local Interconnect Network) is a point-to-point network often used to send data to an actuator or read data from a sensor.
MOST25 – Media Oriented System Transport is an optical 25 Mbps infotainment bus with ring topology. There is also a 50 Mbps MOST50 bus (electrical) used mainly by Asian car manufacturers and an upcoming optical MOST150 bus.
Byteflight – Safety critical bus with star topology used for communication between airbag ECUs, can handle both asynchronous and synchronous data.
Flexray – A successor to byteflight. Used for safety critical communication like “drive-by-wire”.
Safe-by-wire (plus) – A bus dedicated for communication between ECU’s, sensors and actuators in airbag systems.
SPI – Yes, plain old SPI is sometimes used to communicate between simple ECUs.
There are several buses dedicated to diagnosis like J1850, K-line, KWP2000 et.c. but they are all integrated by the OBD2 standard
Experience
We have a genuine experience of automotive ECU design. Especially Airbaig Control Units and Infotainment Control Units, with customers as Autoliv Electronics AB, Volvo Car Corporation and Flextronics Design. This makes us familiar to all the contradicting demands for a vehicle ECU, such as EMC, operational temperature range, immunity to poor voltage supply quality and of course low unit cost.
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