FELIX: The New Readout System for the ATLAS Detector

After the current LHC shutdown (2019-2021), the ATLAS experiment at the LHC at CERN will be required to operate in an increasingly harsh collision environment. The LHC will deliver luminosities up to three times the original design value, with a commensurate increase in the number of interactions per bunch crossing. To maintain physics performance in this new regime, the ATLAS experiment will undergo a series of upgrades during the shutdown. A key goal of this upgrade is to improve the capacity and flexibility of the detector readout system. To this end, the Front-End Link eXchange (FELIX) system has been developed. FELIX acts as the interface between the data acquisition; detector control and TTC (Timing, Trigger and Control) systems; and new or updated trigger and detector front-end electronics. FELIX functions as a router between custom and radiation tolerant serial links from front end ASICs and FPGAs to data collection and processing components via a commodity switched network. FELIX also distributes the LHC bunch-crossing clock, as well as the fixed-latency trigger accepts and resets received from the TTC system, to the front-end electronics. FELIX uses commodity server technology in combination with FPGA-based PCIe I/O cards. FELIX servers run a software routing platform serving data to network clients. This contribution introduces the FELIX system, describes the firmware and software under development, and shows the integration test results prior to the commissioning of next year.