The Migration Challenges to a Time Triggered Paradigm
11.4 TEODACS Development Process
11.4.5 Implementation of the FlexRay Communication Stack
The automated configuration, as presented in the previous chapter, has been applied to two different FlexRay evaluation boards:
• High-end automotive microcontroller: Infineon Tricore TC1797 32-bit con-troller running at 180 MHz with FlexRay CC (CIC310) on chip—starter kit from Infineon
• Low-cost generic microcontroller: Atmel ATMEGA128 8-bit controller running at 16 MHz with Flexray CC (CIC310) connected via SPI—own development
Based on a simple application both implementations have been validated and evaluated. For this simple application a FlexRay cycle time of 5 ms has been used.
The static segment was divided into 80 slots à 16 byte messages; the remaining cycle time was configured to host dynamic slots. For this specific FlexRay con-figuration the overall reception- and transmission-time of a single message has been measured (see Table11.1).
Our example application occupies four static slots for transmission and five static slots for reception. A cpu-load of 3.4% is caused on the TC1797 controller and 28.4% on the ATMEL respectively. The performance differences result from the computing power differences between the two microcontrollers as well as from the different access performances to the FlexRay communication controllers.
Hence, on-chip parallel access (TriCore platform) is more efficient than an external, serial interface (Atmel platform). This experiment highlights two main results.
First, the proposed development flow including the FlexRay configuration stack is suitable for different kind of microcontrollers. Second, the Atmel platform better suits the development of intelligent sensors with low requirement on bandwidth
Table 11.1 Processing time
caused by FlexRay stack Receive (ls) Transmit (ls)
TC1797 20.8 17.3
ATMEGA 128 179.8 130.2
168 E. Armengaud et al.
(only a few messages need to be exchanged). Dedicated microcontrollers (such as TriCore) are required for central ECUs in order to efficiently support the full power of FlexRay.
11.5 Conclusion
The time-triggered paradigm enhances the design flow with the early integration of the timing behavior. This additional system view, on one side, provides interesting properties such as independent node development, stability of prior services or constructive integration at communication level and thus supports the development of (timely) predictable systems. On the other side, this additional timing infor-mation has to be efficiently managed during the entire design process. It is outmost important to keep the timing information consistent across the component boundaries. To that aim, seamless modeling approaches as well as the assistance of dedicated tool chains are required to support the development process. We have presented the design flow used within the TEODACS approach, and experimen-tally evaluated its capacities for a high-end and for a low-cost platform.
Acknowledgments The authors wish to thank the ‘‘COMET K2 Forschungsförderungs-Programm’’ of the Austrian Federal Ministry for Transport, Innovation and Technology (BMVIT), the Austrian Federal Ministry of Economics and Labour (BMWA), Österreichische Forschungs-förderungsgesellschaft mbH (FFG), Das Land Steiermark and Steirische Wirtschaftsförderung (SFG) for their financial support.Additionally we would like to thank the supporting companies and project partners austriamicrosystems, AVL List and CISC Semiconductor as well as Graz University of Technology and the University of Applied Sciences FH Joanneum.
References
1. Hansen P (2005) New S-Class Mercedes: pioneering electronics. The Hansen report on automotive electronics, vol 18, no 8, pp 1–2, Oct 2005
2. Kopetz H, Bauer G (2003) The time-triggered architecture. In: Proceedings of the IEEE, vol 91, no 1, pp 112–126, Jan 2003
3. FlexRay Communications System—Protocol Specification V2.1 Rev A (2005).http://www.flex ray.com, Flexray Consortium, December 2005
4. Time-triggered protocol TTP/C high level specification, Document Protocol Version 1.1, http://www.tttech.com/technology/specification.htm, 2005
5. Kopetz H (1997) Real-time systems: design principles for distributed embedded applications.
Kluwer Academic Publishers, Norwell
6. Kopetz H (1998) The time-triggered model of computation. In: Proceedings of the 19th IEEE Real-Time Systems Symposium, Dec 1998, pp 168–177
7. Obermaisser R (2008) Temporal partitioning of communication resources in an integrated architecture. IEEE Transactions on Dependable and Secure Computing, vol 5, no 2, pp 99–114
8. Kopetz H (1992) Sparse time versus dense time in distributed real-time systems. In:
Proceedings of the 12th International Conference on Distributed Computing Systems, June 1992, pp 460–467
11 Automotive Embedded Systems 169
9. Kopetz H, Obermaisser R (2002) Temporal composability. Comput Control Eng J 13(4):156–162
10. Wilwert C, Navet N, Song Y-Q, Simonot-Lion F (2004) Design of automotive X-by-wire systems. In: Zurawski R (ed) The industrial communication technology handbook. CRC Press, Boca Raton
11. Bauer G (2001) Transparent fault tolerance in a time-triggered architecture. Ph.D.
Dissertation, Technische Universität Wien, Institut für Technische Informatik, Treitlstr.
3/3/182-1, 1040 Vienna, Austria
12. Alber A (2004) Comparison of event-triggered and time-triggered concepts with regard to distributed control systems. In: Embedded World, pp 235–252
13. Almeida L, Pedreiras P, Fonseca JAG (2002) The FTT-CAN Protocol: why and how. IEEE Trans Indus Electron (TIE) 49(6):1189–1201
14. Gwaltney D, Briscoe J (2006) Comparison of communication architectures for spacecraft modular avionics systems. NASA/TM-2006-214431
15. Navet N, Simonot-Lion F (2005) Fault tolerant services for safe in-car embedded systems.
The embedded systems handbook. CRC Press/Taylor & Francis, Boca Raton
16. Scarlett JJ, Brennan RW (2006) Re-evaluating event-triggered and time-triggered systems.
In: 11th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA’06), Sept 2006, pp 655–661
17. Kopetz H, Braun M, Ebner C, Kruger A, Millinger D, Nossal R, Schedl A (1995) The design of large real-time systems: the time-triggered approach. In: Proceedings of the 16th IEEE Real-Time Systems Symposium, Dec 1995, pp 182–187
18. Ebner C (1998) Efficiency evaluation of a time-triggered architecture for vehicle body-electronics. In: Proceedings of the 10th Euromicro Workshop on Real-Time Systems, June 1998, pp 62–67
19. Elmenreich W, Bauer G, Kopetz H (2003) The time-triggered paradigm. In: Proceedings of the Workshop on Time-Triggered and Real-Time Communication, Manno, Switzerland, Dec 2003
20. Kopetz H, Nossal R (1997) Temporal firewalls in large distributed real-time systems. In:
Proceedings of the 6th IEEE Computer Society Workshop on Future Trends of Distributed Computing Systems, Oct 1997, pp 310–315
21. Zug S, Schulze M, Kaiser J (2008) Latency analysis for the cooperation of event and time-triggered networks. In: IEEE International Workshop on Factory Communication Systems, 2008 (WFCS 2008), May 2008, pp 3–9
22. Kajtazovic S, Steger C, Pistauer M (2005) A HDL-independent modeling methodology for heterogeneous system designs. In: Behavioral Modeling and Simulation Workshop, 2005.
BMAS 2005. Proceedings of the 2005 IEEE International, pp 88–93
23. System Architect Designer (SyAD), http://www.cisc.at/SyAD, CISC Semiconductor Design?Consulting GmbH, Lakeside B07, 9020 Klagenfurt, Austria,www.cisc.at, March 2007
24. Schyr C, Schaden T, Schantl R (2008) New frontloading potentials through coupling of HiL-simulation and engine test bed. In: FISITA 2008 World Automotive Congress, September 2008, pp F2008-12-317
25. Watzenig D, Pölzlbauer F, Kaiser J (2007) Fault tracking and failure effect analysis in complex automotive control systems based on a generic modeling approach. In: SAE World Congress 2007, Apr 2007, pp 2007-10-31
26. ASAM MCD-2 NET (2008) Fibex v3.0—data model for ECU network systems.
http://www.asam.net, ASAM
27. Fennel H, Bunzel S, Heinecke H, Bielefeld J, Fuerst S, Schnelle K-P, Grote W, Maldener N, Weber T, Wohlgemuth F, Ruh J, Lundh L, Sanden T, Heitkaem-per P, Rimkus R, Leour J, Gilberg A, Virnich U, Voget S, Nishikawa K, Kajio K, Lange K, Scharnhorst T, Kunkel B (2006) Achievements and exploitation of the AUTOSAR Development Partnership.
In: Convergence 2006, October 2006, p 10
170 E. Armengaud et al.
28. Armengaud E, Tengg A, Karner M, Steger C, Weiss R, Kohl M (2009) Moving beyond the component boundaries for efficient test and diagnosis of automotive communication architectures: In: 14th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA 2009), Sept 2009, 8 pp
29. Armengaud E, Tengg A, Driussi M, Karner M, Steger C, Weiß R (2009) Automotive software architecture: migration challenges from an event-triggered to a time-triggered communication scheme. 7th Workshop on Intelligent solutions in Embedded Systems, pp 95 –103
11 Automotive Embedded Systems 171