Tests of the Fully Loaded CSC Track Finder Backplane M.Matveev S.-J. Lee Rice University

1. Tests of the Fully Loaded CSC Track Finder Backplane M.Matveev S.-J. Lee Rice University Alex Madorsky University of Florida 2 May 2005

2. Goals of the Test • Check all electrical connections between Muon Sorter and 12 Sector Processors (384 “data” + 24 “winner” lines) slots • Check timing and quality of GTLP signals on backplane at 80Mhz  This is actually the first time we are able to check the fully loaded Track Finder backplane • Measure the “safe window” of data latching on Muon Sorter board with 12 Muon Testers (replacement of SP) • Develop and test the software that will be used for future integration tests

3. Muon Tester Board • Designed at Rice in 2004 as a replacement for TMB and SP specifically for peripheral and Track Finder backplane tests

4. Track Finder Crate Under Tests at Rice

5. Software Functionality • Can load random sets of patterns (510 frames) into any number of Muon Testers (1..12) and send them out to Muon Sorter on broadcast command • Can adjust 80Mhz clock on MS input with 100 ps (internal DLL) or 250 ps (external delay chip) step • Read data from FIFO_B and FIFO_C after sorting and verify against expected values Firmware Functionality • In addition to “old” MS functions the MS logic can now mask data from any SP on its inputs

6. Measurements of the “Safe Window” in March • Safe window = 4 ns when MT1-MT6 are sending data simultaneously (192 lines switching at 80Mhz) • Safe window = 2.5 ns when MT7-MT12 are sending data simultaneously (192 lines switching at 80Mhz) • Safe window = 1 ns when all MT1-MT12 are sending data simultaneously (384 lines switching at 80Mhz)  Unacceptable – too narrow. Why?

7. Track Finder Backplane Waveforms (Example) Yellow: X25:B21 (SP4_29). Note X25:C21 is SP4_30. Blue: X25:D15 (SP4_0). Note X25:C15 is GND. Conditions: all 12 Muon Testers are sending data to Muon Sorter (384 lines are switching simultaneously)

8. Track Finder Backplane One of 4 connectors on MS slot (the other 3 are similar) Yellow waveform on previous slide Blue waveform on previous slide SP- to - MS connector

9. Observations • • When 384 MT-to-MS lines are switching simultaneously at 80Mhz, • the quality of signals on lines A[i], B[i], D[i] and E[i] of the backplane • connectors is acceptable if C[i] is GND (i=1…25) on both MS and SP slots. • Signal distortion is significant if C[i] is assigned to signal or +1.5V. •  240 signals out of 384 are at risk •  We haven’t seen such a problem in the peripheral crate. • Note: most C[i] pins on Muon Port Card and TMB slots are grounded • • Signal distortion increases gradually with the number of switching sources •  That explains why the “safe window” is shrinking also gradually • • Ccb_cmd_strobe line (the most important bussed line) is OK for any • number of switching data sources • SP11 signals reception on MS is affected by winner bits training pattern • (winner bits transmitters are located near SP11 receivers, 24 bits)

10. Example of the Peripheral Backplane Waveform Yellow: X39:A10 (TMB1_Data4) Blue: X39:B14 (TMB1_Data21) Conditions: all 9 TMBs are sending data to MPC (288 lines are switching simultaneously)

11. Steps taken to fix the problem on the existing prototypes • Backplane: • Additional grounding provided (copper foil) on both sides • Grounding pins for the Muon Sorter connectors added • Muon Sorter : • Connector shields added, attached to MS ground as well as • possible • Training patterns disabled (24 winner bits switching at 40 • MHz)

12. Track Finder Backplane after modification (rear view)

13. Results after prototype modifications • • Safe data reception window: 3.75 ns – the same as in the • peripheral crate • Such window is considered acceptable (taking into account • the difference in delays in Tx, Rx and backplane) • On both ends of safe window, the errors appear from multiple • sources simultaneously – no single bad source • The system is working as expected

14. Track Finder Backplane Waveforms (same signals) Threshold Threshold Before backplane modification After backplane modification Yellow: X25:B21 (SP4_29). Note X25:C21 is SP4_30. Blue: X25:D15 (SP4_0). Note X25:C15 is GND. Conditions: all 12 Muon Testers are sending data to Muon Sorter (384 lines are switching simultaneously)

15. Backplane revision 2 modifications • All transmission lines to be moved to internal layers, between two ground layers (stripline) • Top and bottom layers flooded with ground • 7-row shielded connectors will be used in MS slot, all C-row pins grounded • 7-row shielded connectors will be used in SP slot • Special 1.5 V distribution layer to MS, bypass capacitors • Grounded mounting holes

16. Muon Sorter revision 2 modifications • Connectors will be replaced with shielded versions, pin assignment to match rev 2 backplane • At least 2 Ground layers, dedicated plane layers for 3.3V and 1.5 V distribution • All transmission lines to be moved to internal layers, between two ground layers (stripline) • Top and bottom layers flooded with ground • Winner bit GTLP transmitters will be shifted away from receivers • Clock line will be provided for GTLP receivers

17. Conclusion • • First prototypes of the TF backplane and Muon Sorter did • not provide a reliable transmission of point-to-point signals • at 80Mhz • After modifications, the system works as expected • • Muon Sorter board and Track Finder backplane designs • have to be modified, and the new boards produced • Required modifications are well understood and tested