Tag Archives: Hard Real-time

A microprocessor designed for real-time predictability and short WCETs

March 26, 2018 08:58 ,

Schoeberl, M., Puffitsch, W., Hepp, S. et al, Patmos: a time-predictable microprocessor, Real-Time Syst (2018) 54: 389, DOI: 10.1007/s11241-018-9300-4.

Current processors provide high average-case performance, as they are optimized for general purpose computing. However, those optimizations often lead to a high worst-case execution time (WCET). WCET analysis tools model the architectural features that increase average-case performance. To keep analysis complexity manageable, those models need to abstract from implementation details. This abstraction further increases the WCET bound. This paper presents a way out of this dilemma: a processor designed for real-time systems. We design and optimize a processor, called Patmos, for low WCET bounds rather than for high average-case performance. Patmos is a dual-issue, statically scheduled RISC processor. A method cache serves as the cache for the instructions and a split cache organization simplifies the WCET analysis of the data cache. To fill the dual-issue pipeline with enough useful instructions, Patmos relies on a customized compiler. The compiler also plays a central role in optimizing the application for the WCET instead of average-case performance.

Posted in: Electronics, Real-Time Systems , Tagged: , ,

A gentle tutorial on Industrial Ethernet

March 15, 2018 09:58 ,

K. Langlois et al., EtherCAT Tutorial: An Introduction for Real-Time Hardware Communication on Windows [Tutorial], IEEE Robotics & Automation Magazine, vol. 25, no. 1, pp. 22-122, DOI: 10.1109/MRA.2017.2787224.

Setting up real-time hardware communication for applications such as precise motion control can be time consuming and confusing. Therefore, this tutorial introduces the deployment of an Ethernet for control automation technology (EtherCAT) protocol. We situate EtherCAT, briefly discuss the origins and working principles, and mention advantages over other widely used protocols. Additionally, the main objectives of the tutorial and the required software to complete it are presented. Online supplements are included, explaining all steps to run a Simulink model in real time on a Windows machine within a few hours.

Posted in: Communication networks , Tagged: ,

A novel method for hard real-time communications using the physical layer of Ethernet and a variation of TDMA

September 20, 2017 08:30 ,

Andrzej Przybył, Hard real-time communication solution for mechatronic systems, Robotics and Computer-Integrated Manufacturing, Volume 49, 2018, Pages 309-316, DOI: 10.1016/j.rcim.2017.08.001.

The paper proposes a method to build a highly efficient real-time communication solution for mechatronic systems. The method is based on the Ethernet physical layer (PHY) and on field programmable gate array (FPGA) technology and offers a better performance when compared to commercially available communication solutions. Although it is not directly compatible with the OSI/ISO model of TCP/IP protocol, vertical integration is done with a gateway. This provides simplicity and safety. Moreover, the use of the FPGA allows for integrating the communication solution with the user algorithm of particular distributed device inside a single chip. Therefore, the proposed solution is efficient and highly integrated.

Posted in: Communication networks, Real-Time Systems , Tagged: