KM3NeT front-end and readout electronics system: hardware, firmware and software

The KM3NeTresearch infrastructure being built at the bottom of the Mediterranean Seawill host water-Cherenkov telescopes for the detection of cosmic neutrinos. The neutrino telescopes will consist of large volume three-dimensional grids of optical modulesto detect the Cherenkov light from charged particles produced by neutrino-induced interactions. Each optical modulehouses 31 3-inch photomultipliertubes, instrumentation for calibration of the photomultipliersignal and positioning of the optical moduleand all associated electronics boards. By design, the total electrical power consumption of an optical modulehas been capped at seven watts. This paper presents an overview of the front-end and readout electronics system inside the optical module, which has been designed for a 1~ns synchronization between the clocks of all optical modulesin the grid during a life time of at least 20 years.