Time Triggered Protocol (TTP/C): A Safety-Critical System Protocol

This paper examines the Time Triggered Protocol (TTP), for the support of distributed real-time systems which has recently emerged from research into the commercial world, and TTP/C, a variant of TTP for safety-critical systems that is coming into use in the automotive industry. The culmination of more than 20 years of effort, TTP has been the focus of more than 100 masters level theses and 25 doctoral dissertations. (1) In the sections that follow, we begin by discussing several requirements of embedded safety critical systems. Next we will describe the TTP/C and many of its key features and compare these features to those of the Controller Area Network (CAN) protocol, which is currently used in automotive systems. This comparison will illustrate why TTP/C, the first instantiation of a TTP primarily for use in automotive systems, is the first protocol to qualify as a SAE (Society of Automotive Engineers) Class C protocol. (2) Finally, we will examine the current state of simulation and modeling of TTP based systems. As part of this examination the authors will outline a proposed approach to high-level modeling of TTP systems.