Run control communication for the upgrade of the ATLAS Muon-to-Central Trigger Processor Interface (MUCTPI)

The Muon-to-Central-Trigger-Processor Interface (MUCTPI) of the ATLAS experiment at the Large Hadron Collider (LHC) at CERN will be upgraded to an ATCA blade system for Run 3, starting in 2021. The new design requires development of new communication models for control, configuration and monitoring. A System-on-Chip (SoC) with a programmable logic part and a processor part will be used for communication to the run control system and to the MUCTPI processing FPGAs. Different approaches have been compared. First, we tried an available UDP-based implementation in firmware for the programmable logic. Although this approach works as expected, it does not provide any flexibility to extend the functionality to more complex operations, e.g. for serial protocols. Second, we used a SoC processor with an embedded Linux operating system and an application-specific software written in C++ using a TCP remote-procedure-call approach. The software is built and maintained using the framework of the Yocto Project. This approach was successfully used to test and validate the MUCTPI prototype. A third approach investigated is the option of porting the ATLAS run control software directly to an embedded Linux instance.