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Updating automotive ECUs over-the-air

Posted: 05 Dec 2013 ?? ?Print Version ?Bookmark and Share

Keywords:Firmware Over-the-Air? FOTA? Electronic Control Units? ECUs? embedded software?

As the amount of software in automobiles grows, so too does the need to effectively manage that software asset. The telecom industry has a proven solution for remotely updating software on mobile devices. The technology is called Firmware Over-the-Air (FOTA) updating. All major mobile phone manufacturers and tier one operators have adopted FOTA successfully, performing more than 100 million updates per year with the benefit of providing new features and performance improvements, reducing customer care costs, avoiding product recalls, and increasing consumer satisfaction.

Today's automobile contains many complex electronic systems; each may incorporate a large number of Electronic Control Units (ECUs) performing a single function and communicating via a common bus/network. In 2009, Prof. Manfred Broy of the Munich Technical University stated that in a premium class automobile there are close to 100 million lines of software code, compared to the F-35 Joint Strike Fighter with 5.7 million lines or with the Boeing 787 with about 6.5 million lines. In addition, Prof. Broy states that "the cost of software and electronics can reach 35 to 40 per cent of the cost of a car." Present day automobiles typically contain more than 60 ECUs such as the audio system, brake system, doors, lighting, engine, transmission, batteries, and more. The embedded software package size now amounts to tens of megabytes for engine and transmission controllers, while audio/infotainment systems are usually the largest and most complex software units, often exceeding 100MB.

How updates in vehicles are performed today
There are many control modules in a vehicle, most of which are interconnected over some form of vehicle network interface (CAN, MOST, LIN, FlexRay). However, only a select few will have access to external cellular or Wi-Fi networks, typically the infotainment head unit or Telematics module. It is possible to use an externally connected module as a gateway for updates, where firmware updates for other modules are received by this gateway module and then transferred to the appropriate module over a vehicle network. In any case, each of the vehicle control modules will potentially be subject to updates.

Figure 1: Software update process: Over-the-Air vs. CAN bus (Image: Vector).

There are several use cases today for updating automobile software: because of recalls (mandatory or voluntary) or customer complaints, during scheduled maintenance or when delivering new features and applications.

The recall case is the most common, and it begins with a vehicle manufacturer finding a problem with the vehicle functionality. The affected functionality can be fixed by changing software in one of the vehicle's ECUs. The appropriate ECU supplier is then requested to provide a new release. The supplier ships the software release to the Original Equipment Manufacturer (OEM), which tests it for quality assurance (QA). After that, the OEM notifies the dealers and owners of the recall via mail. The OEM sends the new software version to the dealers on a CD by mail as well. The dealer updates the reprogramming (serial communication) tools with the content from the CD. The vehicle owner drops off the vehicle at the dealer shop and the technician starts connecting a serial communication tool to the in-vehicle bus to access the targeted ECU. After performing the update and checking the targeted ECU for the new software version to make sure proper re-flashing happened, the customer picks up the updated vehicle und the dealer charges the OEM for the recall labour.

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