The NIMROD is a VME module. The size of the modules probably will be conform the IEEE standard P1101.10, which describes a 9U * 400 mm board. It is foreseen that four NIMRODs may share a VME crate, controlled by a single master. This controller takes care of various settings in the NIMRODs, internal tests, spying on the data stream and possibly sending test data to the ROB. The ROB (Read Out Buffer) is the interface to the ATLAS Data Acquisition System and the second level trigger. Each of the 96 towers in the barrel region has its own NIMROD, connected to 96 ROLs (Read Out Links), which are based on S-LINK. For the Forward MDT system the read out segmentation is still under study.
Each NIMROD accepts a maximum of 32 FELinks (Front-End Links). The average occupancy should not exceed ~40%. The information from the TTC (Trigger Timing and Control) is received by a TTCrx mezzanine card. Each NIMROD has its own ROL (Read Out Link), which cannot be shared. The ROL is driven by an S-LINK mezzanine card. The VME interface is used for various settings at run-time, as a spy channel and to invoke clock phase calibration cycles. The VME interface may also be used to insert test data that is sent to the ROB. The JTAG port is used to perform functional tests of NIMROD only and to set-up the TTCrx board.
CERN - High Speed Interconnect
- S-LINK
Erik van der Bij - 14 January
2000