1. F. Odorici - INFN Bologna
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

2. DT trigger links layout
Detector in UXC
DT front end
Barrel
Trigger Boards
(BTI,TRACO,TSS)
LVDS link:
Ethernet cables FTP cat. 6.
rate 480 max 40 m C B
Minicrate
Server Board
LVDS copper link
Towers in UXC
Sector Collector
Opto link
Opto-link:
multimodal fibers 850 nm m
Counting room in USC
DT Track Finder
DT Sorter
GLOBAL MUON TRIGGER
ESR for Muon DT minicrate System (3 nov 03)
F. Odorici - INFN Bologna

3. Trigger Server to SectorCollector LVDS link
For each Trigger Server use a unique stream for  & :
bits (2 40 MHz
LVDS link on < 30m shielded copper cable:
2 cables/minicrate (Ethernet class 6 FTP, 4 pairs/cable)
Chipset from National Semiconductors:
Serializer 10-to-1 DS92LV1021 (8 chip/link)
Cable equalizer CLC014 (8 chip/link)
Deserializer 1-to-10 DS92LV1212A (8 chip/link)
Total quantities: 2000 links (chipsets) + 12 km of cable
Serializer
10 to 1
Deserializer
1 to 10
Equalizer TX RX
ESR for Muon DT minicrate System (3 nov 03)
F. Odorici - INFN Bologna

4. 2x40 m ethernet cable FTP cat.6
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 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

5. F. Odorici - INFN Bologna
LVDS link test setup RX TX
40m Cable
Pattern Units
ESR for Muon DT minicrate System (3 nov 03)
F. Odorici - INFN Bologna

6. Expected Working Condition in CMS
LVDS link test results
Expected Working Condition in CMS
LVDS link
working range
Power Supply
VCC  5%
VCC  10%
Ambient Temperature
< 50o
20o ÷ 80o
Cable Length
Max 30m
1 ÷ 40m
Clock (no Jitter)
40 MHz
16 ÷ 49 MHz
Jitter tolerance
& BER
Jitter = 48 ps Jp-p = 360 ps
( TTCrx without QPLL
@ -20dBm attenuation )
Jitter ≤ 80 ps Jp-p ≤ 800 ps
BER, tested up to (has no impact on DT muon efficiency)
ESR for Muon DT minicrate System (3 nov 03)
F. Odorici - INFN Bologna

7. SectorCollector to DT-TrackFinder opto-link
 stream : 110 bit (4 tracks) per 40 MHz;
 stream: 42 bit (3 tracks) per 40 MHz;
Opto-link with multimodal 850 nm fibers (length < 100 m):
use 1.6 Gb/s (32 40 MHz):
 stream : 4 links/sector;
 stream: 2 links/sector;
360 links/detector;
Laser (Tx) and PIN-detector (Rx) under evaluation
PIN
GOL
Deserializer
TLK 2501
VCSEL
Agilent HFBR HFBR-782 Honeywell HFE HFD
ESR for Muon DT minicrate System (3 nov 03)
F. Odorici - INFN Bologna

8. SectorCollector to DTTF opto-link arrangement
1 Plugin board/ DTTF  4 Rx / board
Wedge arrangement: +2 +1 +0 -0 +2 -1 +1 -2
DTTF 
Wheel –2 to +2
(6 board/wedge) -1 -2
Sector Collector
Wedge xx
Wheel –2 to +2
(5 board/wedge)
Same board-layout
The two boards for wheel –0 and +0 share same inputs from SC of wheel 0
DTTF 
Full Wedge
(1 board)
40 LVDS Rx / sector
6 GOL Tx / sector
2 Plugin board/ DTTF  5 Rx / board
DTTF crate- backplane
ESR for Muon DT minicrate System (3 nov 03)
F. Odorici - INFN Bologna

9. 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

10. 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

11. The phase of the DT trigger decision
The phase associated to the DT trigger decision, wrt CMS, depends mainly on three factors:
clock paths:
how the timing Trigger and Control system (TTC) is distributed (fiber lengths) among the trigger sub-systems.
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:
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

12. F. Odorici - INFN Bologna
DT trigger paths
Detector in UXC R P C T I G E C S T R I G E
DT front-end
Barrel
250 Stations’ minicrates
Trigger Boards
(BTI,TRACO,TSS) C B
TTC opto link
Server Board
Chamber Control Board
LVDS copper link
TTC opto link
Sector Collector
Towers in UXC
Opto link
DT Track Finder
TTC opto link
DT Sorter
Counting room in USC
DT Regional Trigger
GLOBAL MUON TRIGGER
ESR for Muon DT minicrate System (3 nov 03)
F. Odorici - INFN Bologna

13. DT’s TTC distribution in UXC55 (Cavern)
To 5 wheels:
2 Sector Collector crates/wheel: TTCrx/Sect.C.crate
Counting room
TTCvi
2+2spare
2+2spare
1+1spare
1+1spare 20
TTCex
2+2spare
Tower (Left) 25 25
Tower (Right)
2+2spare
TTCoc 1:32
TTCoc 1:32
2+2spare
~ 100 m 1 1
Q.ty
TTCvi 1
TTCex
TTCoc (1:32) 10
TTCrx
260
Fibers 100m 20
Fibers 10÷30m
250
Fibers 1.5 m
Sector Collector crate
Sector Collector crate
~ 10÷30 m
Fibers from TTCoc-to- minicrateTTCrx might have different lengths!
50 minicrates/wheel 1 TTCrx/minicrate
ESR for Muon DT minicrate System (3 nov 03)
F. Odorici - INFN Bologna

14. DT’s TTC distribution in USC55 (Counting room)
Sector Processors (14 modules/crate) & Wedge Sorters (2 modules/crate)
~ 5 m
~ 2.5 m
TTCvi
Sectors & wedges (6 crates) 1
TTCoc 1:16 7
TTCex
Global Sorter & DAQ (1 crate) 1
Q.ty
TTCvi 1
TTCex
TTCoc (1:16)
TTCrx 7
Fibers 5m
Fibers 2.5m
A TTCrx, on an Interface Module, sitting in the center of each crate.
Fibers for all crates can have same lengths!
ESR for Muon DT minicrate System (3 nov 03)
F. Odorici - INFN Bologna

15. DT sub-systems clock distribution
Chamber Control Board:
Distributes TTCrx clocks up to 7 trigger boards (+7 DAQ boards);
clock skew tuned with individual delay lines (0.5ns step);
Detector in UXC
DT front end
Barrel
Trigger Boards
(BTI,TRACO,TSS) C B
Minicrate
Server Board
Sector Collector crates:
TTCrx master module distributes Clock (BC0, L1A and Reset), via backplane LVDS signals, to all SCs
Clock skew tuned to < 1 ns.
LVDS copper link
Towers in UXC
Sector Collector
Opto link
Counting room in USC
DT Track Finder
Regional Trigger crates:
TTCrx master module distributes Clock (BC0, L1A and Reset) via backplane LVDS signals
DT Sorter
GLOBAL MUON TRIGGER
ESR for Muon DT minicrate System (3 nov 03)
F. Odorici - INFN Bologna

16. F. Odorici - INFN Bologna
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
and Server Board (cable lengths)
10 ns
Sector Collector
TTCoc-to-minicrateTTCrx opto-fiber lengths (10÷30m)
100 ns
Particle time of flight on stations
9 ns
LVDS cable lengths (10÷30m)
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

17. F. Odorici - INFN Bologna
How to synchronize
Our approach:
Relative BX synchronization distributed on 3 levels:
Minicrate, Sector Collector, Regional Trigger.
At each level, a local synchronization is performed to compensate for skew due to transmission from the previous level.
A coarse synchronization (± 1 BX resolution) is obtained via pipe-lines. BX tagging: each minicrate forwards the BCreset information.
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

18. Local synchronization
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.
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).
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

19. Final remarks on synchronization
Cabling (copper and fibers) of stations, wheels etc. can be performed without requiring equal lengths and zero skew (easier & cheaper).
Opto-fibers between UXC & USC (TTC and trigger opto-links) have equal lengths.
Loss of Synchronization is checked (at each BX) by comparing the Bunch Counter value (2 LSbits) after each transmission step.
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