FlexRay™ technology is enjoying growing acceptance in the automotive industry. The number of converts familiarizing themselves with this relatively young bus technology is steadily rising. But FlexRay™ is by no means simple, making it all the more important to go tread carefully.
The amount of time it takes to get your mind around unknown bus technology and work out just how things function depends partly on the development platform involved. In the perfect world you would be dealing with an end-to-end solution which is easy to grasp and does not take long to become familiar with. It should encompass all the components you need to take your first steps. To understand FlexRay™ technology, it is important to present beginners with a clearly expressed concept before they start to master each component.
Once they understand the overall concept, design engineers like to get to know FlexRay™ network technology quickly by setting up a sample network and seeing how it communicates – but even getting to this point means overcoming obstacles. The first thing they need is at least two suitable hardware platforms to work as a FlexRay™ node. To work with the platform they then need a computer, programming hardware, and a debugger. But the biggest hurdle to overcome when starting out with FlexRay™ is to configure the FlexRay™ controller. Before configuring a FlexRay™ bus you have to be clear about when a message is sent or received. Because everything is timed, things need to be planned in advance by laying down parameters for each bus element. It’s almost impossible to do this without the aid of special configuration software, apart from which the developer has invested a great deal of effort getting to know the hardware platform as the system does not usually come with a program for running the FlexRay™ controller.
Now help is on hand from products developed by the Microelectronics Steinbeis Transfer Center (TZM) in Göppingen. They have developed a low cost solution based on a FlexDevel platform using an MPC5567 processor from Freescale. The platform offers a variety of interfaces. The board already comes with integrated bus drivers for the two FlexRay™ and CAN HS channels as well as the LIN, Ethernet and RS232 interfaces. Two h-bridges allow you to connect two DC motors which can be run on separate current supply connections. An optional LCD module can be connected via an interface on the FlexDevel board. Each FlexDevel platform comes with a comprehensive library of ANSI C software allowing for low-level functions on every interface of the processor to start operating interfaces quickly and without hassle. As the library is delivered in source code it can be adapted to individual needs.
Sample software comes with each of the library modules using simple applications to demonstrate how to use the modules. For example to start operating the FlexRay™ interface there are two sample programs which are both based on the FlexRay™ library module that comes with the system. The sample software is installed with the programming adaptors on the two FlexDevel platforms that come with the system, so FlexRay™ communication starts straight away.
You can track data being transferred via the serial interfaces. Based on the sample software it does not take long to create your own applications. The user manual is broken down by hardware and software. The hardware section contains detailed information on existing interfaces and which steps to go through to start operating the FlexDevel platform. The software section goes into detail about the installation of the necessary programs held in an installer (Eclipse, GNU compiler, P&E debugger, manuals, datasheets, library, examples).
The TZM offers two FlexDevel starter packs. The first, “FlexDevel Kit”, contains FlexDevel cards including two FlexRay™ connection leads for setting up a basic FlexRay™ network. To configure the network the package includes FlexConfig demo software. This tool allows you to lay down the bus-specific parameters for timed FlexRay™ communication. To simplify system specifications, the pack includes some useful features, such as plausibility checks or threshold measurement of the selected parameters. Once the configuration set has been prepared, the bus components can be configured by integrating the generated configuration files into the software application.
The other pack, “FlexDevel Starter Kit” offers all the elements found in the “FlexDevel Kit” as well as a bus interface card called “FlexCard Cyclone II” with accompanying software. This hardware allows you to analyze FlexRay™ communication on a PC. The analysis software that comes with the package, “FlexAlyzer basic“ enables asynchronic or synchronic monitoring of data flows. The kit also includes other functions such as generation of different trigger signals or filtering functions. If needed, data can also be recorded (data logging) and stored in a file.
To complete the package, the “FlexDevel Starter Kit“ comes with a two day FlexRay™ seminar on the theoretical and practical aspects of bus technology.
Thorsten Kopp
Steffen Gugenhan
Steinbeis Transfer Center Microelectronics (Göppingen)
stz130@stw.de