A data readout system with high-speed serial data link for balloonborne X-ray detectors

Data size of recent balloonborne detector is growing. High speed data readout is one of the key technologies for those detectors. A parallel data bus has been used for sending data with high speed. However, it causes problems in noise, mechanical size and power consumption. We apply the serial data link for our apparatus as a replacement of the parallel data link to solve those problems. We designed the hardware and firmware based on the SpaceWire protocol. Because of simple and flexible routing protocol of SpaceWire, the system was compact and has very high modularity. The protocol is implemented on Altera´s FPGAs, APEX20KE and Cyclone. The speed of the serial data link was 48-53 Mbps. The maximum data rate to the computer was 4.5 MB/s.