FlexRay Transceiver Performs Embedded Bit Reshaping

The AS8224 FlexRay Active Star Device, a transceiver for FlexRay-based in-vehicle networks, performs embedded bit reshaping, which reduces the asymmetric delay caused in FlexRay networks by either the network components themselves or by external interference. The AS8224 device can reshape bits in 12.5-ns steps up to a total amount of 37.5 ns for shortened and lengthened bits. Above and beyond bit reshaping, the device performs 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 (12.5 ns). The bit-reshaping function can be set as an option and will operate 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 transceiver without timing reshaping. The AS8224 is an Active Star device complying with 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. The optimized Interstar interface, in combination with the signal handler, allows two or more connected AS8224 devices to exhibit timing behavior similar to a single device. AUSTRIAMICROSYSTEMS AG, Unterpremstaetten, Austria. +34 91 792 4878.