Design and Performance of a PCI Interface with four 2 Gbit/s Serial Optical Links

A reconfigurable PCI interface card (FILAR) with four on-board high-speed serial optical links has been developed for application in DAQ and test systems. FILAR cards, installed in low cost PCs, are currently being used in the combined test-beam of the ATLAS experiment at CERN as well as in several laboratory set-ups. The hardware and firmware design of the module and results from performance measurements are presented. The four on-board 2 Gbit/s serial optical links conform to the S-LINK specification and are compatible with the Readout Link (ROL) implementation for the ATLAS experiment. The board design is largely based on FPGAs and the firmware uses a commercial 64-bit/66 MHz PCI IP core for the bus interface. Different firmware versions were developed which can be used to configure the hardware as either a data source or a destination card. Design optimizations have been made during the development cycle of the firmware to maximize the data throughput and reduce the PCI bus overhead as well as the CPU load. In a PC with multiple PCI segments an aggregate data throughput of over 1.5 Gbyte/s has been measured and transfer rates of more than 100 kHz have been achieved.