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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?

The update duration changes significantly depending on the module size and the speed of the serial protocol; however due to a lot of overhead, dealers are charging 1-2 hours of labour for such activity. There are some car models where the update can take more than 2 hours. It should be noted that programming tools are rather expensive, so there is a limit to the number of simultaneous re-programming.

Current software programming via cable
There are limitations and constraints with current software distribution and software update processes:

???Any update is distributed to all dealers. This takes time and resources. It may also cause delays in getting the latest software to the vehicles. In addition, all dealers need to maintain a software version library, which consumes resources.
???The download process and the manual setup take a long time, resulting in higher cost of labour, inconvenience, and customer dissatisfaction. Due to this long duration, the consumer needs to drop off the vehicle and return later to pick it up C a major inconvenience.
???The process cannot be scaled or preformed in parallel, as it involves a physical equipment connection.
???Some existing re-flashing methods require sequential updates, meaning from version 1 to 2 to 3, which can make the entire update process longer.
???Sometimes (for off-highway vehicles), the re-flashing equipment needs to be mobilized to the vehicle.
???It may take a long time from when the customer is notified to the time the vehicle is actually updated. Many customers do not respond to recall notices. For older vehicles, the OEM may not have the latest vehicle owner information, meaning some vehicles never receive needed updates. Conducting a successful recall depends on the customer cooperation.
???Reprogramming of the ECU is performed manually.
???The customer becomes aware of the problem and overall customer satisfaction decreases.
Of course, there are also some advantages to the current reprogramming (cable-based) method:

???While FOTA is gaining wide acceptance for new automotive platforms, it will take few years until FOTA is a widely adopted solution in the automotive industry.
???Reprogramming is performed in the controlled environment.
???The vehicle is not moving and it is under technician supervision while the reprogramming occurs.
???This methodology is proven and it has worked in the past.
???Any problem that occurs has more chances to be detected immediately by a trained technician.
???Vehicle wired serial communication protocols and algorithms for reprogramming are proprietary and closed source by nature. As such, protocols provide an added layer of security against unauthorised software changes.

Figure 2: FOTA update process architecture.

The FOTA update technology
The current method of updating software in cars was suitable when the amount of software was minimal. Now that software has become vital to the operation and feature-set of cars, the method of software updating must be improved.

It is clear that performing the update in the customer location and not in the dealership represents a better and more optimised method in term of cost savings and user experience. However, it can introduce some potential procedure challenges such as how to make sure that the car will not be driven in the middle of the update. Therefore, FOTA adoption in the automotive industry will take more time to become fully operational.

The FOTA update process comprises three primary stages: generating the update, managing the delivery of the update, and performing the update.

Generating the update package
To perform a FOTA update, a software update package containing defect fixes or new features must be generated. In order to make this package as small as possible (in general it is less than 5% of the original size), the update package includes only the changes (also referred to as the "delta") between the version that already exists on the ECU and the new version being deployed to the vehicle. This update package is typically generated by the owner of the software, most often a tier I vendor.

Managing the delivery of the update package
Once generated, the update package is published to a distribution platform. In the mobile industry, this platform is managed by either the mobile phone manufacturer or the network operator. In automotive, this platform is managed by the OEM. This platform manages the various versions of the update packages and handles the actual network delivery (download) of the packages to the appropriate vehicle model and specific ECU. There are typically multiple versions of update packages, each intended for particular vehicle models and configurations. This portion of the process can be an integral part of an overall Telematics or over-the-air (OTA) diagnostics system.

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