  The efficient utilization of available resources while simultaneously
achieving control objectives is a primary motivation in the event-triggered
control paradigm. In many modern control applications, one such objective is
enforcing the safety of a system. The goal of this paper is to carry out this
vision by combining event-triggered and safety-critical control design. We
discuss how a direct transcription, in the context of safety, of
event-triggered methods for stabilization may result in designs that are not
implementable on real hardware due to the lack of a minimum interevent time. We
provide a counterexample showing this phenomena and, building on the insight
gained, propose an event-triggered control approach via Input to State Safe
Barrier Functions that achieves safety while ensuring that interevent times are
uniformly lower bounded. We illustrate our results in simulation.
