Difference: AMC13UserManual (18 vs. 19)

Revision 1913 Jul 2015 - EricHazen

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THIS MANUAL IS INCOMPLETE but what is written here should be more accurate and up to date than the old "functional specification". Please e-mail me if you find mistakes/omissions here (Eric H).
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  int getTTCHistoryCount(); // get TTC hsitory count

Local Trigger Logic (DT)

The following section describes a local trigger implemented for the DT group according to the following specification: DT AMC13 requirement (rev 2015-06-05). This trigger logic is contained entirely in the T2 (Spartan) FPGA and is introduced in version 0x29.

This trigger uses Fabric B inputs from 12 AMC modules and TRIG0 and TRIG1 from special T3 board as inputs to a 14-bit Look Up Table to generate a trigger at every TTC clock cycle.

To align the trigger inputs, there is an 8 bit delay line at each trigger input. The unit of the delay is one eighth of a TTC clock cycle. To help adjusting the delays, there is a sampling buffer of 14-bit and 1024 deep which samples the delayed input trigger at eight times of the TTC clock frequency.

Before using the trigger, delay adjustment is necessary.

  • First, write 1 to register 0x101 to enable the trigger.
  • Second, fill the LUT with 0xffffffff except 0x200 which should be loaded with 0xfffffffe. This results a trigger of simple OR of all fourteen trigger inputs.
  • Then write 1 to register 0x100 to enable the sampling.
  • After that send a signal to all fourteen trigger source so that LUT will receive trigger from all of them.
  • Read out the sampling buffer and first adjust the three LSB of the input delay so that the trigger will be recorded with the same seven MSB of the sample buffer read address. (assuming the input trigger signal is 25 ns wide, otherwise the trigger should be centered in the bins at least), this ensures the LUT clock edge is always optimally centered.
  • Next adjust the seven MSB of the input delay so that all input trigger have the same seven MSB address of the sample buffer.
This calibration should be repeated whenever possible to correct for possible timing drift due to temperature/voltage changes.

LUT trigger uses registers in the range of 0x100-0x10f and 0x200-0x7ff


Local Trigger Logic (HCAL)

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 A local trigger may be formed from 8 bits supplied each BX from each AMC card. There are a total of 8 independent logic triggers which are evaluated every BX and output on an optical fiber at 1.6 Gb/s (actually the TTC clock times 40) with 8b10b encoding.
(Fabric B is not used because the HCAL uHTR did not connect it!)
  Each of the 8 individual logic triggers works as follows:
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