Date: 08/12/2008

FlexRay active star device with embedded bit-reshaping functionality

Austria Microsystems has released AS8224 FlexRay active star device transceiver with embedded bit-reshaper, the solution for the most limiting FlexRay system parameter. The embedded bit-reshaper reduces the asymmetric delay either caused by components in FlexRay networks or introduced by external interferences onto the network. The bit-reshaper design is capable of reshaping single bits in 12.5 ns steps (microtick) up to a total amount of 37.5 ns (3 microticks) for shortened and lengthened bits. The mechanism performs, besides of the timing reshaping, a clock-deviation compensation between the input and output stream of the device while the BSS (Byte-Start-Sequence) of the FlexRay frame is shortened or lengthened by one microtick. The bit-reshaping function can be set as an option and will be functional if an external clock is connected to the device. Otherwise, the bit-reshaper will be bypassed and the device acts as a standard Active Star without timing reshaping.

"The AS8224 with embedded bit-reshaper enables FlexRay topologies beyond today's applications and allows network topologies with more than one Active Star" comments Harald Gall, Product Manager In-vehicle Networks at Austria Microsystems. "We do not only design and develop our products within the FlexRay specifications, our target is to understand the FlexRay system in detail and to facilitate improvements for our customers beyond the standard."
The AS8224 with embedded bit-reshaper is an Active Star device according the FlexRay Electrical Physical Layer Specification V2.1 Rev B operating as an active hub for 4 FlexRay network branches, the communication controller interface and an interstar interface. Message forwarding is performed including these 6 communication paths. The optimized interstar interface in combination with the Signal Handler allows two or more connected AS8224 devices to display a timing behaviour similar to one single device.