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					                           DT Trigger links



       Outline:
        From local trigger to Sector Collector
        From Sector Collector to Regional Trigger




ESR for Muon DT minicrate System (3 nov 03)   F. Odorici - INFN Bologna   1
                                DT trigger links layout

Detector          DT front end
                       Barrel
in UXC


                 Trigger Boards           C     LVDS link:
Minicrate      (BTI,TRACO,TSS)            C
                                          B     • Ethernet cables FTP cat. 6.
                  Server Board
                                                • rate 480 Mbps @ max 40 m
              LVDS
              copper
               link
Towers in        Sector Collector
  UXC
                Opto
                link                            Opto-link:
 Counting
 room in         DT Track Finder                • multimodal fibers 850 nm
   USC
                    DT Sorter                   • 1.6 Gbps @ 100 m

            GLOBAL MUON TRIGGER


  ESR for Muon DT minicrate System (3 nov 03)    F. Odorici - INFN Bologna   2
           Trigger Server to SectorCollector LVDS link

•      For each Trigger Server use a unique stream for  & :
       -    80 bits (2 tracks)/BX @ 40 MHz
•      LVDS link on < 30m shielded copper cable:
       -    2 cables/minicrate (Ethernet class 6 FTP, 4 pairs/cable)
       -    Chipset from National Semiconductors:
            a) Serializer 10-to-1 DS92LV1021 (8 chip/link)
            b) Cable equalizer CLC014 (8 chip/link)
            c) Deserializer 1-to-10 DS92LV1212A (8 chip/link)
•      Total quantities: 2000 links (chipsets) + 12 km of cable


    Serializer                                                                  Deserializer
     10 to 1
                   TX                             Equalizer          RX          1 to 10

    ESR for Muon DT minicrate System (3 nov 03)     F. Odorici - INFN Bologna            3
                         LVDS link test

• Test of 8 links: 8 serializers + 8 (equalizers + deserializers) as
needed for a complete Trigger Server data transfer.
• Use two cables of 40 m (max foreseen is 30 m).
• Inject random patterns @ 40 MHz                 TX rate: 480 Mbps




                                     Succesfully tested for:

                                     • expected working conditions,
                                     • Clock jitter tolerance,
                                     • Bit Error Rates,
                                     • radiation tolerance.


                   2x40 m ethernet
                   cable FTP cat.6
                              LVDS link test setup




                                                       RX




                                              TX
                                                                               40m Cable
     Pattern Units




ESR for Muon DT minicrate System (3 nov 03)        F. Odorici - INFN Bologna        5
                             LVDS link test results

                           Expected Working                      LVDS link
                           Condition in CMS                     working range
Power Supply                        VCC  5%                         VCC  10%

Ambient
                                       < 50o                           20o ÷ 80o
Temperature

Cable Length                         Max 30m                           1 ÷ 40m

Clock (no Jitter)                     40 MHz                        16 ÷ 49 MHz

                         Jitter = 48 ps Jp-p = 360 ps    Jitter ≤ 80 ps Jp-p ≤ 800 ps
Jitter tolerance                                            BER, tested up to 10-12
                           ( TTCrx without QPLL
& BER                                                     (has no impact on DT muon
                          @ -20dBm attenuation )                    efficiency)



  ESR for Muon DT minicrate System (3 nov 03)     F. Odorici - INFN Bologna        6
           SectorCollector to DT-TrackFinder opto-link

•       stream : 110 bit (4 tracks) per sector/BX @ 40 MHz;
•       stream: 42 bit (3 tracks) per sector/BX @ 40 MHz;
•      Opto-link with multimodal 850 nm fibers (length < 100 m):
       -     use GOL @ 1.6 Gb/s (32 bits @ 40 MHz):
                   -      stream : 4 links/sector;
                   -      stream: 2 links/sector;
                   -     360 links/detector;
       -     Laser (Tx) and PIN-detector (Rx) under evaluation


                                                                       Deserializer
        GOL            VCSEL                       PIN                  TLK 2501
                           Agilent HFBR-772            HFBR-782
                           Honeywell HFE4190-541       HFD3180-102


    ESR for Muon DT minicrate System (3 nov 03)    F. Odorici - INFN Bologna          7
     SectorCollector to DTTF opto-link arrangement

                                                      1 Plugin board/ DTTF 
 Wedge arrangement:
                                                      4 Rx / board                                              +1
                                                                                                                  +2

                                                                                                           +0
                                                                                                      -0
                                                 +2                                              -1
                                            +1                                              -2



                                   -1
                                        0
                                                                               DTTF 
                              -2                                             Wheel –2 to +2
                                                                             (6 board/wedge)
            Sector                                         Same
           Collector                                      board-
                                                          layout                                      The two boards
            Wedge xx                                                                                   for wheel –0
          Wheel –2 to +2                                                                               and +0 share
         (5 board/wedge)                                                       DTTF                   same inputs
                                                                               Full Wedge               from SC of
                                                                                (1 board)
                                                                                                          wheel 0




40 LVDS              6 GOL Tx / sector                    2 Plugin board/ DTTF                  DTTF crate-
Rx / sector                                               5 Rx / board                            backplane
   ESR for Muon DT minicrate System (3 nov 03)                 F. Odorici - INFN Bologna                               8
                        Summary on Trigger links

 Two transmission technologies adopted:
    • LVDS ser/des for chamber-to-towers (UXC) data transfer:
           extensively tested (reliabile, jitter & radiation tolerant)
    • Gigabit opto-link for tower-to-DTTrackFinder (USC) TX:
           based on GOL; other components under evaluation;
           ongoing tests with prototype links;
           final decision by may 2004.


 RX error detection (at each BX):
     check of parity bits at each transfer step;
     error flagging but no error recovery.

 ESR for Muon DT minicrate System (3 nov 03)   F. Odorici - INFN Bologna   9
             DT Trigger Synchronization



                    Outline:
                     Trigger system paths
                     Signal skews
                     TTC distribution, clock ...
                     How to synchronize



ESR for Muon DT minicrate System (3 nov 03)   F. Odorici - INFN Bologna   10
                The phase of the DT trigger decision


The phase associated to the DT trigger decision, wrt CMS, depends
   mainly on three factors:
•    clock paths:
     o     how the timing Trigger and Control system (TTC) is
           distributed (fiber lengths) among the trigger sub-systems.
     o     how the TTCrx clock is configured (in term of delay
           settings) in each sub-system and how it is distributed to the
           nearby electronics;
•    trigger data paths:
     o     how many BXs take the processing step in each sub-system
           and how longs are paths (cables) for each data transfer.
•    particles time of flight in the detector.


    ESR for Muon DT minicrate System (3 nov 03)   F. Odorici - INFN Bologna   11
                               DT trigger paths

                              DT front-end                         Detector in UXC
                                   Barrel


R       C                                                          250 Stations’
                                                                    minicrates
P       S                    Trigger Boards    C
C       C                  (BTI,TRACO,TSS)     C                  TTC
                                               B                opto link
                              Server Board
T       T                                                 Chamber Control Board
                          LVDS
R       R                 copper
I        I                 link
G       G                   Sector Collector             TTC                Towers in
                                                       opto link              UXC
G       G
                            Opto
E       E                   link
R       R                   DT Track Finder
                                                           TTC
                               DT Sorter                 opto link
                                                                             Counting
                                               DT Regional                   room in
        GLOBAL MUON TRIGGER
                                                 Trigger                       USC

ESR for Muon DT minicrate System (3 nov 03)     F. Odorici - INFN Bologna           12
            DT’s TTC distribution in UXC55 (Cavern)

                            To 5 wheels:                     2 Sector Collector crates/wheel:
                                                                  1 TTCrx/Sect.C.crate
                                2+2spare
  TTCvi
                                2+2spare
                                                       1+1spare                               1+1spare
                  20            2+2spare
  TTCex                                                            25                    25
                                2+2spare         TTCoc                                             TTCoc
Counting room
                                2+2spare         1:32                                               1:32
            ~ 100 m
                                                       1                                                      1
                   Q.ty
                                                  Sector                                             Sector
   TTCvi             1                           Collector                                          Collector
                                                  crate                                              crate
   TTCex             1
                                                 Tower                                               Tower
TTCoc (1:32)        10
                                                 (Left)                                             (Right)
   TTCrx           260
                                                                                    ~ 10÷30 m
 Fibers 100m        20            Fibers from TTCoc-to-
Fibers 10÷30m      250            minicrateTTCrx might                          50 minicrates/wheel
 Fibers 1.5 m       10            have different lengths!                        1 TTCrx/minicrate
   ESR for Muon DT minicrate System (3 nov 03)               F. Odorici - INFN Bologna                   13
   DT’s TTC distribution in USC55 (Counting room)

                                                       Sector Processors (14 modules/crate)
               ~5m                 ~ 2.5 m              & Wedge Sorters (2 modules/crate)

   TTCvi
                                                              Sectors &
                   1      TTCoc         7
   TTCex                                                       wedges
                           1:16                               (6 crates)

                                                            Global Sorter
                                                1             & DAQ
                 Q.ty
                                                              (1 crate)
   TTCvi          1
  TTCex           1
                                                       A TTCrx, on an Interface Module,
TTCoc (1:16)      1                                    sitting in the center of each crate.
  TTCrx           7
 Fibers 5m        1
                                       Fibers for all crates can have same lengths!
Fibers 2.5m       7

 ESR for Muon DT minicrate System (3 nov 03)        F. Odorici - INFN Bologna       14
                 DT sub-systems clock distribution

Detector          DT front end                  Chamber Control Board:
                       Barrel
in UXC
                                                • Distributes TTCrx clocks up to 7
                                                trigger boards (+7 DAQ boards);
                 Trigger Boards           C     • clock skew tuned with individual
Minicrate      (BTI,TRACO,TSS)            C
                                                delay lines (0.5ns step);
                                          B
                  Server Board
                                                Sector Collector crates:
              LVDS
              copper                            • TTCrx master module distributes
               link
                                                Clock (BC0, L1A and Reset), via
Towers in        Sector Collector               backplane LVDS signals, to all SCs
  UXC
                Opto                            • Clock skew tuned to < 1 ns.
                link
 Counting
                 DT Track Finder
 room in                                        Regional Trigger crates:
   USC
                    DT Sorter                   • TTCrx master module
                                                distributes Clock (BC0, L1A and
            GLOBAL MUON TRIGGER                 Reset) via backplane LVDS signals

  ESR for Muon DT minicrate System (3 nov 03)    F. Odorici - INFN Bologna   15
                                    Skew summary
DT trigger informations are distributed through the system and
transmitted on different paths: they have to be correlated (at
various stages) with the right time-phase to provide a correct
trigger decision. The skew on signals from equivalent sources
(stations, sectors, wheels ...) must be cancelled, i.e.
compensated.
Sub-system            Source of skew                         Max estimated skew
Minicrate             Clock among Trigger Boards                        10 ns
                      and Server Board (cable lengths)
Sector Collector      TTCoc-to-minicrateTTCrx                          100 ns
                      opto-fiber lengths (10÷30m)
                      Particle time of flight on stations               9 ns
                      LVDS cable lengths (10÷30m)                      100 ns
Regional Trigger      Opto-fiber lengths (90÷100m)                      50 ns
                                                               Total: 269 ns (11 BX)

  ESR for Muon DT minicrate System (3 nov 03)         F. Odorici - INFN Bologna        16
                             How to synchronize

Our approach:


1. Relative BX synchronization distributed on 3 levels:
      Minicrate, Sector Collector, Regional Trigger.
2. At each level, a local synchronization is performed to
   compensate for skew due to transmission from the
   previous level.
3. A coarse synchronization (± 1 BX resolution) is
   obtained via pipe-lines. BX tagging: each minicrate
   forwards the BCreset information.
4. A fine synchronization is obtained via clock delay lines:
   scanning and centering of clock-edge vs data-edge.


ESR for Muon DT minicrate System (3 nov 03)   F. Odorici - INFN Bologna   17
                               Local synchronization

1. Minicrate:
•   BTI synchronisation (BX identification via HighQualityTriggers and mean
    timer method):
    fine tuning (up to 0.1 ns) of hit sampling on each station (via TTCrx).
•   Skew among TRBs and Server Board:
    fine delays (0.5 ns) of individual clocks.
2. Sector Collector (4-5 stations/sector):
•   TTC fibers, Time-Of-Fligth and LVDS cable compensation:
    via clock delay lines (fine, 0.5 ns) and pipe lines (coarse, 0÷16 BXs).
3. Regional Trigger:
•   Opto-fiber lengths compensation:
    delay (fine, 0.5 ns) & pipe lines (coarse, 0÷8 BXs) after opto-receivers.
•   All DT modules must be synchronous on different crates:
    fine tuning (0.1 ns) of clock via TTCrx.
    ESR for Muon DT minicrate System (3 nov 03)   F. Odorici - INFN Bologna   18
                  Final remarks on synchronization


a) Cabling (copper and fibers) of stations, wheels etc. can be
   performed without requiring equal lengths and zero skew
   (easier & cheaper).
b) Opto-fibers between UXC & USC (TTC and trigger opto-
   links) have equal lengths.
c) Loss of Synchronization is checked (at each BX) by
   comparing the Bunch Counter value (2 LSbits) after each
   transmission step.
d) The absolute BX assignement is obtained by histogramming
   the BX occupancy wrt BCreset.




 ESR for Muon DT minicrate System (3 nov 03)   F. Odorici - INFN Bologna   19

				
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