austriamicrosystems has introduced the AS8224, a FlexRay active star device with an embedded bit-reshaper that reduces the asymmetric delay caused by components in FlexRay networks or introduced by external interferences onto the network.
The AS8224 FlexRay transceiver can reshape single bits in 12.5 ns steps (microtick) up to a total amount of 37.5 ns (3 microticks) for shortened and lengthened bits. In addition to timing reshaping, the device can effect clock-deviation compensation between the input and output streams 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 reshaper will be bypassed and the device will act 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,” said Harald Gall, austriamicrosystems product manager for in-vehicle networks.
The AS8224 with embedded bit-reshaper is an active star device according the FlexRay Electrical Physical Layer Specification V2.1 Rev B. It operates as an active hub for four FlexRay network branches, the communication controller interface, and an interstar interface, and it performs message forwarding for all six communication paths.
The optimized interstar interface, together with the signal handler, allows two or more connected AS8224 devices to display a timing behavior similar to one single device.