The Clover VXI card ( Inner contact card :HRGe8X ) creates singles data for each of its eight channels, and transfers it to a VME module using a single 40Mhz. 4 bit serial data link. The VME module contains memory and links for either four or eight Clover VXI cards.
The Clover VXI card operates in different modes depending on the experimental requirements. These modes, and how they affect the True Singles operation, are detailed in the document "Constant Fraction Control Logic" by N.Karkour, and A.Richard.
The VME module is a CES RIO 8062 PowerPC card running LynxOS. The Clover VXI card serial links connect to a mezzanine board, mounted on the VME module, containing a DSP (Digital Signal Processor), four link connections, memory, and a high speed bus ( PCI ) connection to the PowerPC, and VME.
The DSP is the Analog Devices ADSP21062, which includes six 40Mhz. 4 bit serial links in each chip. Input data from the links is stored in memory on the mezzanine board, translated by the DSP to histogram addresses, and transferred via the PCI bus to the PowerPC as 16k buffers. The transfer rate over the PCI bus for block transfers of this sort is 100Mbytes/sec.
To accommodate slow rate experiments all the input, and internal buffers will be flushed when no transfer to the PowerPC has occurred for 1 second. The buffers can be flushed by specific request from the experimental control software; typically when the experiment is stopped, and started. Memory required per channel: 8K data, 16 time frames = 512Kbytes.