Straw electronics

Straw Readout Board (SRB)

Full SRB - IO

• Handling 16 covers– Input 16*2 links 400(320eff) Mbits/s

• Control– TTC– LEMO– VME

• Output – to PC farm – 2*1Gb/s ethernet– VME to SBC– L0 trigger– Choke/error

Straw detector output data flow

• Straw detector– 4 chambers

• 4 views each (x,y,u,v)

• ½ view is served by SRB (Straw Readout Board)– 2 SRBs/view– 8 SRBs/chamber– 32 SRBs/detector

• 2 x 1Gbit/s ethernet interfaces per SRB• 1 chamber connected through 10Gbit link (+1 spare) to

pc-farm– 16 Gbit links merged in a switch

Data rates

• Single straw rate 60kHz (average)– 48 bits/event (24 bits leading, 24 bits trailing)– Coarse time in header

• L0 1MHz rate with time window 250ns– Total data rate per SRB with protocol (UDP,IP,..)

• 440 Mbit/s

– Total data rate per chamber with protocol• 3.6 Gbit/s

– Full detector ~16Gbit/s• Without L0 and without protocol

– 600->800 Mbit/s per SRB– Full data 4.8->6.4 Gbit/s per chamber

Details UDP header (bytes) 12max UDP length (bytes) 65500MEP header (bytes) 8event header (bytes) 8max IP length (bytes) 9000IP header (bytes) 38edge hit size (bytes) 3Event rate (Hz) 1.00E+06Hits per view 6Time window (s) 2.50E-07Rate (tracks) per View (Hz) 1.80E+07

events in time window 1.40E+01event data (bytes) 102event size header+dati (bytes) 110max number of events in UDP packet 595data rate (bytes/s/view) 110000000UDP packets/s/view 1680effective IP packet length (bytes) 8962number of IP packets/s/view 12278total data to tranfer (Mbit/s/view) 884.016total data to tranfer (Mbit/s/station) 3536.064

SRB – components

TTC

LEMO

L0 OUT ETH

COVERS

TTCRx

COVER CONTROL,

DATA, SYNCH

EVENT PROCESSOR

2(4)GB DDR3

DATA TO PC FARM

TIME REMAP

L0 PROCESSOR

VME INTFON-LINE

MONITOR

L0 LOOK_UPTABLE

L0 OUT SRB

SRB – control flow

Selectable control- TTC- LEMO- VME

Clock delay to compensate time of flight,Group of 4 covers

VME to- Setup- Control,- On-line monitoring- Data

SRB – data flow

16x2x320Mbit/s ~10Gbit/s

2.5Gbit/s

2x Gbit ethernet

VME

Alternative path

SRB – trigger data flow

16x2x320Mbit/s ~10Gbit/s

2.5Gbit/s

2x Gbit ethernet

VME

L0 PRIMITIVES

Alternative path

Trigger • First mentioned in TD• Possibility to use Straw detector

for L0 if proved to be useful• Tracks or hit multiplicity• Tracks

– View is split to corridors• 6 straws

– Corridors overlap on each side by 2 straws

– 2 or more trailing edges in a corridor in a defined time window qualify a track

– Can be already used as a coarse position ~13mm

Trigger • Position can be improved

using leading edges• Leading edges from 6

straws put into the time pipeline corresponding to the full drift time in straw, step 25ns

• Trailing edge track signal starts pattern recognition

• Leading edges are run though look-up table and output position code

• Time-corresponding position codes from all views are combined

To look-up table

6 straws leading edges

Trigger • 1 SRB with modified firmware collects primitives from 8 SRBs serving

1 chamber• OR • 1 SRB with modified firmware collects primitives from 16 SRBs

serving 2 chambers• Chambers 1,2 and 3,4 can either contribute alone or can be combined• L0 SRB send L0 primitives to L0 processor• Time estimate

– Event to Cover to SRB – <500ns– Time-reordering of hits - 10us– Track finding - <1us– Collection of hits and combination < 10us– Sending L0 primitives in < 22us

Choke/error

• Use user-defined VME P2 line• Open collector output from every SRB• Wire-OR to combine all outputs• Simple VME board to convert choke/error

wire-OR signals to RJ45 standard• Use 1 calorimeter choke/error collection board

to combine outputs from all chambers and send to L0 processor

• Monitoring via VME

SRB conclusions• Design started

– Schematics – Big part of prototype board firmware could be reused– New parts

• Time reordering• Event buffer management• data format for pc-farm• Online monitoring• L0 trigger

• Ready for PCB layout in November• Prototype January/February 2014• Price estimate

– Components < 1 kCHF– PCB + assembly < 1 kCHF– Total < 2 kCHF

• Integration/dry-run between April-June 2014