L2 & L3 Data from L1Cal

updated: 01-Dec-04

Index

  1. General Format
  2. L2 Data from the TABs
  3. L2 Data from the GAB
  4. Transfer Times
  5. Notes
  6. Version 1 (12-Jun-04)

General L2/L3 Data Format

See also the Level 2 Trigger Hardware page and Run IIa L1Cal to L2 data list.

The L1Cal system sends identical data to L2 and L3. Optical splitters are used on the fibers sent out from the TABs and GAB.
Type 19 18 17 16 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
H 01 01 Header Length No. of Objects
H 00 00 H Format Obj Format Object Length
H 00 00 Crossing No. (L1_BX) L2 Data Type
H 00 00 Turn No. (L1_TURN)
H 00 00 Firmware Min Ver Firmware Maj Ver
H 00 00 L2 Status Processor Bits
 
D 00 00 Data
D 00 00 ---
D 00 00 Data
 
T 00 00 L2 Data Type Crossing No. (L1_BX)
T 00 00 Vertical Parity
 
P 00 00 Pad (0)
P 00 00 ---
P 10 10 Pad (0)

L2 Data from the TABs

The TAB Global Chip is in charge of transferring this data to the G-Link transmitter on each TAB. Each TAB sends out two types of information.

  1. The raw (8-bit) Et's received from the ADFs: 2 x 40 x 4 values in EM/HAD x eta x phi space.
  2. Three bit-masks with individual bits = 1/0 if a EM/JET/TAU object with Et over a specified threshold was found at a given position: 3 x 31 x 4 bit in EM/JET/TAU x eta x phi space.
Only data is shown. Headers, trailers, pads and control bits are as above.

No. 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
1 EM(0,5) H(0,5)
2 EM(1,5) H(1,5)
3 EM(2,5) H(2,5)
  --- ---
4 EM(39,5) H(39,5)
5 EM(0,4) H(0,4)
  --- ---
160 EM(39,2) H(39,2)
 
161 EM>L2-Thr Mask (phi=5; eta=19..4)
162 0 EM>L2-Thr Mask (phi=5; eta=34..20)
  --- ---
167 EM>L2-Thr Mask (phi=2; eta=19..4)
168 0 EM>L2-Thr Mask (phi=2; eta=34..20)
 
169 JET>L2-Thr Mask (phi=5; eta=19..4)
170 0 JET>L2-Thr Mask (phi=5; eta=34..20)
  --- ---
175 JET>L2-Thr Mask (phi=2; eta=19..4)
176 0 JET>L2-Thr Mask (phi=2; eta=34..20)
 
177 TAU>L2-Thr Mask (phi=5; eta=19..4)
178 0 TAU>L2-Thr Mask (phi=5; eta=34..20)
  --- ---
183 TAU>L2-Thr Mask (phi=2; eta=19..4)
184 0 TAU>L2-Thr Mask (phi=2; eta=34..20)

L2 Data from the GAB

The GAB sends to L2/L3 some processed information and the trigger terms it sends to the framework. The exact nature of the processed data that can be sent is limited by the data that is transmitted between the TABs and the GAB. A possible format could contain the following information.

  1. Sum(Et) and MEt Data
  2. The Trigger Terms (and/or terms) sent to the Framework
  3. Some test information, for development of new triggers
Only data is shown. Headers, trailers, pads and control bits are as above.

No. 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
1 Sum(EM+H Et)
2 Sum(EM+H Ex)
3 Sum(EM+H Ey)
 
4 Trigger Terms 63-48
5 Trigger Terms 47-32
6 Trigger Terms 31-16
7 Trigger Terms 15-0
 
8 Test Trigger Terms
9 Test Trigger Terms
10 Test Trigger Terms
11 Test Trigger Terms

Timing

L2/L3 Data is tranferred from each of the TAB's and the GAB using a G-Link transmitter running in 20-bit mode (with 16 data bits per cycle). The clock rate for this transmitter is 53 MHz leading to a bit transmission rate of 1.06 Gbit/s.

Total transfer times are given below.
Board TAB/GAB Internal G-Link Xmit Time Total Time
(from L1Accept)
TAB 1.4 us
(SW-->Global)		 [6(header) + 184(data) + 2(trailer) + 0(pad)] / 53Mhz = 3.62 us 5.0 us
GAB 0 [6(header) + 11(data) + 2(trailer) + 5(pad)] / 53Mhz = 0.45 us 0.5 us

Notes

  1. Transmission is by G-link in 20-bit mode. The highest order 4 bits are used to flag begin and end of event.
  2. L2 Data transimission must be padded to a multiple of 8, 20-bit words
  3. Each TAB is responsible for a 40x4 (etaxphi) region of EM and H data. The 4 phi's it sends out correspond to phi-inputs 2-5 (out of 0-8)
  4. Because of the Local Maximum finding requirements, each TAB can find 31x4 (etaxphi) LMs. These correspond to TAB-local eta = 4-34 and phi = 2-5.