Standardization is gaining acceptance in automotive electronics, though automakers often opt for a range of specifications for similar applications. As the number of airbags increases, three suppliers are banding together to promote a standard connection.
Denso Corp., Freescale Semiconductor, and TRW Automotive Holdings recently established an industry consortium to drive further development and deployment of the Distributed Systems Interface (DSI) standard. The DSI Consortium will work to develop the DSI 3.0 standard, with plans to send it out for review before year’s end.
Forming a consortium lets other members join, adding support for a standard that is already used by many automakers. DSI, which links sensors and airbag controllers, faces competition from an emerging alternative. PSI5 has also seen acceptance by automakers.
“DSI is not the only standard; it’s used mostly in Japan and North America. In Europe, we deal with PSI5,” said Hans-Gerd Krekels, Director of Technology Strategy & Core Electronics for TRW Electronics Engineering. A PSI5 consortium is headed by Bosch, Continental, and Autoliv.
Standards are seeing more adoption as more airbags are located throughout vehicles. Using standards can reduce costs by increasing competition, and it can also reduce certification periods by changes in this aspect of the design. In safety systems, safeguards against electromagnetic interference are getting more attention as infotainment systems and other electronic features generate more interference.
“EMI from something like the electric power steering system with high current can’t impact the airbag sensor,” said Martin Thoone, Vice President of TRW Automotive Electronics Engineering. “DSI has two wires that are differentially controlled, so we get common mode suppression and good EMI protection."
George Backos, Product Development Manager for TRW’s Safety Core Development Group, noted that “EMC is one of the key challenges in these systems. There are so many sensors around the vehicle that wiring is much more complicated.”
Along with protection, the developers have focused on speed. The initial specification, which has a 150-kbaud transmission rate, was developed mainly by TRW and Freescale in the late 1990s. Denso joined the effort in 2005 to help develop Version 2.0, which runs at 200 kbaud. Version 3.0 will further improve speed, using more techniques that are tailored to the data sent between sensors and airbag controllers.