Performance and upgrade of the CMS electromagnetic calorimeter trigger for Run II

The CMS experiment implements a sophisticated two-level online trigger selection system that achieves a rejection factor of nearly $10^5$. The level one (L1) trigger is based on coarse information coming from the calorimeters and the muon detectors while the high-level trigger combines fine-grain information from all sub-detectors. In the near future the LHC will increase its centre of mass energy to 13 TeV and progressively reach an instantaneous luminosity of $2\times 10^{34}\,\textrm{cm}^{-2}\textrm{s}^{-1}$. In order to guarantee a successful and ambitious physics program under this challenging environment, the CMS Trigger and Data acquisition system must be consolidated. In particular the L1 calorimeter Trigger hardware and architecture will be changed. The aim is to maintain the current thresholds and improve the performance. This programme will be achieved by using $\mu$TCA (Advanced Mezzanine Card) architecture with fast optical links and latest generation FPGAs. Sophisticated object reconstruction algorithms, as well as online pile-up corrections, are being developed that will make use of these new hardware capabilities. The future L1 calorimeter trigger hardware will be described, together with the novel algorithms implemented on the chips. The performance of this new system will be presented.