Developers of operating systems for embedded systems in the automotive market have had to come to terms with that perennial networking problem - the moving target.When adding the optimum comms network to their vehicle designs, the car manufacturers have moved very quickly up through the gears, from the CAN bus to LIN. But as the use of electronic systems in cars has become more widespread and complex - particularly with the advent of in-car telematics - the search for higher speed buses has moved in to the area of optical fibre communications with MOST (media oriented systems transport).
Suppliers of real-time operating systems (RTOS) have had to track these changes and introduce support for MOST-based in-car fibre networks.
Green Hills Software teamed with German firm Oasis Silicon Systems to offer MOST networking support for in-car telematics reference platforms, based on its Integrity RTOS.
The aim is to integrate the RTOS closely to established networking hardware platforms in order to reduce development cost - traditionally a crucial issue for much automotive design work.
MOST is a multimedia optical fibre network optimised for automotive applications which defines the protocol, hardware and software layers controlling the real-time packet data network.
Green Hills chose the Freescale (formerly Motorola Semiconductor Products Sector) Total5200 telematics reference system, based on the MPC5200 PowerPC processor, for its first MOST RTOS support.
The latest versions of Green Hills Integrity and velOSity operating systems will provide improved support for automotive designs, including speech recognition, echo cancellation, GPS, Bluetooth and Java, as well as MOST.
Wind River Systems also ensured there was solid support for MOST with its Platform CI automotive-specific integrated embedded platform for car telematics.
Launched last year, Platform CI also extends processor support to include MIPS, XScale, ARM, PowerPC, and SuperH processors.
The aim, says Marc Serughetti, director of marketing for automotive, industrial, aerospace and defence at Wind River, is to help developers design car telematics devices quickly and cost effectively.
QNX Software Systems was another early mover when it came to providing RTOS support for the MOST network standard. Last year its Neutrino RTOS was selected by Hyundai's automotive multimedia electronics business unit for a driver information system platform.
This telematics platform was one of the first to use the MOST networking standard, the beauty of which, says QNX, is that it allows the system hardware to simultaneously run navigation systems, hands-free phone modules, entertainment screens, and other multimedia applications.
Putting C in cars
Another issue which RTOS developers have to pay attention to in automotive system design is the potentially costly ambiguities in the C language.
""As a result of its incredible flexibility, the C language is probably the most widely-used high-level language in embedded systems today. This flexibility comes at a cost however,"" says Green Hills Software. ""Ambiguities in the C language, along with certain syntaxes, mean that software developers must often spend countless unexpected hours finding bugs.""
To try and overcome this the Motor Industry Software Reliability Association (MISRA) has published MISRA C, a formal set of guidelines for programming in the C language. The aim of this seems to be to identify aspects of the C language that should be avoided due to their ambiguity and susceptibility to common programming mistakes.
While MISRA C is a set of guidelines for a software developer, it is not a specification for a compiler which means RTOS developers have to support it in the standard release of all 32- and 64-bit products.