Sliding Windows to Global Chip Data Transfer in the TAB

updated: 08-Feb-07

Index

• Version 1 (13-Jul-04)

Data Format

Notes

1. Cluster Data Format
   Only SW chips (1-8) send out cluster information. Cluster types and positions are given in the format: Type(eta,phi) [for example EM(4,1)], where:
   • Type = EM, Jet
   • eta = relative eta index of cluster sent out from this chip (0-8 - note only 2-5 are output)
   • phi = relative phi index of cluster sent out from this chip (0-8 - note only 2-5 are output)
   The highest threshold passed by EM and Jet clusters is encoded as in 3-bits as follows:

   3-bit Value	Meaning
   0	This cluster is not a local maximum
   1-7	This cluster is a local maximum Value = index of highest Et threshold passed

   
   
2. Tau Isolation Data Format
   Only SW chips (1-8) send out tau isolation information. For each eta,phi position the ratio:
   Et(2x2) / Et(4x4)
   is calculated and compared against 7 possible thresholds. The highest ratio threshold passed is encoded as in 3-bits as follows:

   3-bit Value	Meaning
   0	This cluster is not a local maximum
   1-7	This cluster is a local maximum Value = index of highest ratio threshold passed

   
   
3. Sums
   Constructed of EM+H TT Et's summed over all 4 eta bins in each phi-slice ouput by the chip.
   • Sum(EM Et) outputs, present in the Run IIa L1Cal, but not used in any triggers have been suppressed. No use for these is foreseen in the current L1Cal trigger.
4. L2/L3 Data
   Each SW chip buffers its unique 4x4 (in eta x phi) region of EM and H input TT's on each BC. It sends the data from the appropriate BC to the Global chip on the TAB for each L1 Accept at 90 MHz. Data is multiplexed onto 2 output lines.
   • Time required for transfer:
     1(em/h) x 4(eta) x 4(phi) x 8-bits x 11ns/bit / 2-lines = 0.7 us
     (not taking into account any framing bits)
5. Status Bits Definition
   Normal Status = 0x801
   

   Bit	Definition
   11	sync
   10..08	BC Error (encoded to indicate which cable(s) have BC mismatches)
   07	data sync alignment error
   06	0 (unused)
   05	parity error (cable 1)
   04	parity error (cable 2)
   03	parity error (cable 3)
   02	error flag
   01	pll not locked
   00	pulse signal valid for next 12 cp90 steps (shifted first)

6. EM-Isolation and EM/HAD-Fraction Bits
   For each of the 16 EM objects, the corresponding bit in these two words is:
   • 1 if the object passes both EM-Isolation & EM/HAD-Fraction cuts
   • 0 otherwise