What is AUTOSAR, and why does it have Classic and Adaptive platforms?

Why your car's software comes in two flavours

AUTOSAR stands for AUTomotive Open System Architecture. It is not a product you buy, it is a shared rulebook that lets one supplier's brake code and another supplier's infotainment code run on hardware from a third company without every automaker writing its own operating system from scratch. That rulebook exists in two separate versions, Classic and Adaptive, and the gap between them explains a lot about how a modern car is wired together.

The idea began in August 2002, when engineers from BMW, Bosch, Continental, DaimlerChrysler and Volkswagen held a kick off workshop to tackle a problem each of them faced alone, according to AUTOSAR's own history page. A car's electronic control units, the small computers running everything from power windows to fuel injection, were multiplying faster than anyone could manage with bespoke software written fresh for each one. The partnership they formed has since grown to carmakers and suppliers well beyond the founding five.

Classic: the rules for a part that cannot be late

AUTOSAR's first deliverable, Classic Platform Release 1.0, was published in May 2005, per AUTOSAR's history page. Classic is built for the small microcontrollers inside a car's dozens of individual ECUs, the ones that fire an airbag, hold a wheel on its line or open a window. These jobs must happen the same way every single time, within milliseconds, with no chance of a stray update changing the behaviour mid drive. Vector Informatik, one of AUTOSAR's oldest tool suppliers, describes Classic as built for resource constrained microcontrollers running safety critical, high frequency control tasks with direct access to the hardware. Classic code runs close to the metal, under a thin real time operating system, and is almost never touched once a car leaves the factory.

Adaptive: built for a car that keeps changing after sale

AUTOSAR's history page marks March 2017 as the start of work on the Adaptive Platform, the same month its older Classic Platform moved into a slower maintenance phase. Adaptive targets a different kind of chip altogether, the powerful, car sized versions of a data centre processor that now sit at the centre of a software defined vehicle, handling camera and radar fusion, parking assist and the car's link to the cloud. Vector describes Adaptive as running on POSIX based operating systems, commonly Linux or QNX, built to support service oriented software that can be swapped or updated after the car has already been sold, exactly the over the air update loop that defines a software defined vehicle.

KPIT Technologies, the Pune headquartered engineering firm that works only in automotive software, sells its own Adaptive AUTOSAR stack called KSAR Adaptive. According to KPIT's own product page, it runs on Yocto Linux and QNX and has been ported to chips from Qualcomm, Texas Instruments, Renesas and Xilinx. This is the layer of work that Indian engineering services firms increasingly build for automakers who would rather not write it themselves, which is why AUTOSAR appears so often in embedded job postings out of Pune and Bengaluru.

Why the split still matters

A car built today typically carries both platforms at once. Classic still runs the brake controller and the airbag module because that code has to behave identically for the life of the vehicle. Adaptive runs the central computer that an automaker promises will get smarter through updates. Knowing which platform sits behind a given feature is a fair way to judge whether a claim of new capability arriving through a future software update is plausible. Only code built on Adaptive is designed to change after the sale. Code built on Classic, by design, is not.

Sources

• AUTOSAR history
• KSAR Adaptive Platform with AUTOSAR 20-11 Release, KPIT
• AUTOSAR Classic and Adaptive, Vector Informatik