1. Trigger Frequency Analysis & Busy/Veto on the SCT TIM
HEP Electronics
Trigger Frequency Analysis
& Busy/Veto on the SCT TIM
John Lane Martin Postranecky, Matthew Warren
24 Sept 2003
John Lane – SCT Week - CERN

2. TIM Veto of fixed frequencies
TIM is not a solution to wire bonds breaking.
TIM can veto fixed frequency triggers.
Cal signal frequency to be randomised.
TIM Veto vs Busy
Standalone: Veto Triggers, consecutive L1IDs.
RunMode: Stop triggers by Busy back-pressure, non-consecutive L1IDs?
N.B. L1IDs: does ROD need to know about missing triggers?
24 Sept 2003
John Lane – SCT Week - CERN

3. Xilinx Fast Fourier Transform
Drop-in firmware ‘core’ for Spartan II FPGA’s.
High performance 32-point complex FFT.
Precision parameterizable from 2 to 31 bits.
Support for overlapping data input, transform and output operations.
Logic utilisation on TIM FPGA about 50%.
Detailed study required.
Not suitable for existing prototype TIM’s.
24 Sept 2003
John Lane – SCT Week - CERN

4. Repetitive Trigger Busy Module
Compares successive trigger periods, increments counter if matching.
Matching ‘tolerance’ programmable.
Generates Busy when counter hits preset limit.
Busy duration programmable to 1.6 seconds.
Period min/max setting for ‘freq. window’ operation
Ignores triggers outside range (bandpass filter)
Can use more than one module for better resolution.
Low FPGA resource utilisation (on Spartan II 600E)
preset version: 50 ‘slices’ out of 6900.
register configurable version 100 slices.
24 Sept 2003
John Lane – SCT Week - CERN

5. Repetitive Trigger Busy Simulation
Period Max = 1000, Period Min = 400 (25ns units). Threshold = 4.
Freq>max ignored
Freq<min
Freq in window
Trig
Period Max
Period Min
Period
Period Match Threshold
Period Match Count
Busy
24 Sept 2003
John Lane – SCT Week - CERN

6. John Lane – SCT Week - CERN
Conclusion
TIM can implement busy/veto firmware against fixed frequency triggers without hardware changes.
Could do several fixed frequencies in a range.
Beware of L1ID.
Need more study and information on requirements.
24 Sept 2003
John Lane – SCT Week - CERN