The data path of the ATLAS Level-1 calorimeter trigger preprocessor

The PreProcessor of the ATLAS Level-1 Calorimeter Trigger provides digital values of transverse energy in real-time to the subsequent object-finding processors. The input comprises more than 7000 analogue signals of reduced granularity from the calorimeters of the ATLAS detector. The Level-1 trigger decision must be verified. For this, the PreProcessor transmits copies of the real-time digital data to the Data Acquisition (DAQ) system. In addition, the PreProcessor system provides a standard VMEbus interface to the computing infrastructure of the experiment, on which configuration data is loaded and control or monitoring data are read out. A dedicated system that ensures both the transfer of event data to storage in ATLAS and the data transfer over the VME was implemented on the 124 modules of the PreProcessor system in the form of a "Readout Manager". The "Field Programmable Gate Array" (FPGA) is located on each module. The first part of this work describes the algorithms developed to meet the functionality of the Readout Manager. The second part deals with the tests that were carried out to ensure the proper functionality of the modules before they were installed at CERN in the ATLAS cavern.