Modern automotive systems consist of many different ECUs (electronic control units). During the production process of the automotive system, these ECUs must be programmed with application software for mass production. The EOL (end-of-line) programming process is either done during the assembly of the final automotive system by the OEM (original equipment manufacturer), or by the part suppliers for the single components. With the continuous increase of software complexity, the sizes of the hex files and of the ECU flash ROM (read-only memory) increase, so today already several megabytes of data have to be programmed, i.e. more and more data has to be transmitted to the ECU. However, the time allowed for (re-)programming is limited by the production cycle times that stay constant or even go down to meet the requirements of modern mass production. So, long programming times cause unwanted additional costs as for example for parallel programming stations. In other words, reducing programming time can help to save money in the production process. Besides, long programming times are also undesirable in the development process. In this article, we described the application of data compression to reduce the programming times of automotive ECUs over the CAN bus. As the data transmission over CAN is a bottleneck for the programming times, data compression can help to speed up programming. The automotive environment with the embedded systems and limited resources has specific requirements and thus not all compression algorithms can be used. Especially decompression should be fast. The algorithms should be able to handle empty memory areas with good performance. Different algorithms were compared on a file basis first. Especially the LZ-family showed good performance. The algorithms had stable performances over a great number of realistic sample files. It was explained that the application data area could be better compressed than the application code area. The development process had only a minor effect on the compression gains. Due to the strong dependence on the controller type, the results must be verified for each controller. We discussed several aspects that are affected by the bootloader implementation. Furthermore, it was proposed how a simulation tool can be used to simulate the complete programming process including data compression and decompression without the time-consuming target implementations. Finally, alternatives to data compression were presented.
Data compression algorithms for EOL flash programming of automotive ECUs with CAN
2010
21 Seiten, 10 Bilder, 1 Tabelle, 7 Quellen
Conference paper
English
Data compression algorithms for EOL flash programming of automotive ECUs with CAN
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