ATLAS NIMROD
NIKHEF MDT Read Out Driver

(NIKHEF/Amsterdam)


DESCRIPTION

The NIMROD (NIKHEF MDT Read Out Driver) concentrates the data from a number of TDCs (e.g. of a tower of muon chambers) into a single output. The output drives the ROL (Read Out Link). The unit receives trigger and timing information from the CTP (Central Trigger Processor) and distributes this to the TDCs. The information is received by means of a TTCrx chip (Trigger Timing and Control receiver chip).

NIMROD connectionsThe 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.


STATUS

14 January 2000 - NIMROD without the S-LINK port has been used by the L3 experiment. No plans to continue development or use this device in ATLAS. See MROD pages for a description of the new project reading out the MDT.

DOCUMENTATION


CONTACTS


CERN - High Speed Interconnect - S-LINK
Erik van der Bij - 14 January 2000