Commissioning of the Upgraded CSC Endcap Muon Port Cards at CMS

We report on the status of commissioning of the upgraded Muon Port Cards in the Level 1 Trigger electronic system serving the Endcap Cathode Strip Chamber (CSC) sub-detector at the CMS experiment at CERN. After presenting an overview of the existing system and upgrade requirements, we describe the new Muon Port Card FPGA mezzanine and its firmware developed to drive the new 3.2Gbps optical links. Results of initial tests with the existing and upgraded CSC Track Finder boards and further plans are given in the concluding sections.