Build simple and inexpensive FlexRay nodes

In the short term, CAN will co-exist with FlexRay in various applications in the vehicle, before it is gradually replaced—and it appears that FlexRay with its promise of X-by-wire capabilities is going to be very successful. Flexible and versatile, FlexRay also will work alongside other proven networks such as the Local Interconnect Network (LIN) and the Media Oriented Systems Transport bus (MOST).

FlexRay provides multiple benefits across a wide range of vehicle applications. These advantages include high speed, fault tolerance, and a deterministic cycle-based message transport, along with a synchronized, common time base to all nodes and an autonomous start-up process. A network built with FlexRay as the backbone provides such features for steer-by-wire, brake-by-wire, and other applications.

What's in a node?
The first and the most important issue is to understand the importance of the FlexRay node. Within each node, a FlexRay module includes everything that's required to take advantage of two of the FlexRay protocol's most critical features: fault tolerance and deterministic performance.

Node elements include the register block, which contains the control registers that configure a FlexRay device. The register block also includes registers for tracking and providing updated information on protocol status. There is also a message buffer interface which the CPU needs in order to receive and transmit data, including information that comes from the register block itself.

The timing unit, which handles timing control and clock synchronization, is here as well, along with a protocol "state" system which executes protocol logic that includes startup, error, and message handling, and other communications. Finally, the node hosts the all-important receive and transmit units.

So the node's a critical piece of the FlexRay-based design. How can a designer get one started?

Page 2: FlexRay node design
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