  A readout system based on the Timepix4 ASIC, is being developed for photon
science. The TEMPUS detector can be operated in two distinct modes: a photon
counting mode, which allows for conventional full-frame readout at rates up to
40 kfps; and an event-driven time-stamping mode, which allows excellent time
resolution in the nanosecond regime in measurements with moderate X-ray flux.
In this paper, we introduce the initial prototype, a single-chip system, and
present the first results obtained at PETRA III and ESRF.
