Data acquisition in TileCal/ATLAS experiment. Design of the optical multiplexer board prototype

The optical multiplexer board is one of the elements present in the read out chain of the tile calorimeter in ATLAS experiment. Due to radiation effects, two optical fibers with the same data come out from the front end boards to this board, which has to decide in real time which one carries good data and pass them to the read out driver motherboard for processing. This paper describes the design and tests of the first prototype, implemented as a 6U VME64x slave module, including both hardware and firmware aspects. In this last, algorithms for cyclic redundancy code checking are used to make the decision. Besides, the board may be used as a data injector for testing purposes of the read out driver motherboard