Towards self-timed logic in the Time-Triggered Protocol

Abstract

While asynchronous logic has many potential advantages compared to traditional synchronous designs, one of the major drawbacks is its unpredictability with respect to temporal behavior. Without having a high-precision oscillator, a self-timed circuit's execution speed is heavily dependent on temperature and supply voltage. Small fluctuations of these parameters already result in noticeable changes of the design's throughput and performance. This indeterminism or jitter makes the use of asynchronous logic hardly feasible for real-time applications. In this work, we make first steps towards an asynchronous TTP (Time-Triggered Protocol) controller. We will present circuits which use the deterministic data-bus of TTP in order to derive a suitable time-base for message reception and transmission. Speed fluctuations due to changing operating conditions will be compensated automatically by our design, thus increasing robustness and precision. In preparation for the envisioned asynchronous TTP controller, we will integrate the proposed circuits into a (self-timed) message transceiver unit and investigate its precision and dynamics under changing operating conditions.