ABSTRACT
The time–triggered (TT) approach is generally preferred for safety–critical systems. The communication controller in a TT system decides autonomously when a message is transmitted. The communication network interface is a temporal firewall which isolates the temporal behavior of the host and the rest of the system. TT communication protocols support the management of the complexity in an integrated architecture such as AUTomotive Open System ARchitecture. The four fundamental services of a TT communication protocol are explained, namely, clock synchronization, the periodic exchange of state messages, fault isolation, and diagnostic services. The sequence of the different time division multiple access rounds forms the cluster cycle and determines the periodicity of the TT communication. A TT communication protocol and the corresponding system architecture need to provide rules for partitioning a system into independent fault containment region. This section gives an overview of four important representatives of TT communication protocols: time-triggered protocol (TTP)/C, TTP/A, Time-triggered controller area networks, and TT Ethernet.
