Trip-T Front End Board Documentation/Trigger Outputs

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Trigger Outputs

This note refers to the trigger outputs on the RJ45 labelled PL2. This connector comprises 4-LVDS pairs allocated as 1 input pair and 3 output pairs. The locations of these are shown in this document: TFB Connectors (PDF). Until build 81, the Global Trigger Output pair was allocated as a test trigger permitting the user access to either the pipeline reset signal, a 160ns pulse synchronous with the start of the bunch train. From build 54, a programmable pulse has been software selectable instead. This permits the user to decide on the location and duration of the trigger output within the bunch-train structure.

The functionality of the PL2 RJ45 signals can be summarised as follows:

INPUT PAIR 0 (pins 1/2): This pair form an input to the TFB. They are currently unused.

OUTPUT PAIR 2 (pins 4/5): This pair carry a copy of the preamp reset (PreReset) signals to the Trip-t chips. This functionality has not changed since Build 24. This feature allows to check that a TFB generated test pulse (with programmable start offset) is falling within a preamp integration window.

[ Output pair 1 (pins 3/6) and output pair 3 (pins 7/8): The functionality of these signals depends on bit 4 in Cosmic Mode Register 532 (see address 532 in the user firmware register map). Flipping the polarity of bit 4 swaps the functionalities of pairs 1 and 3. ]

OUTPUT PAIR 3 (pins 7/8): If register 532 is set to 0 (Test Trigger) then this pair outputs the Test Trigger signal. If register 532 is set to 1 (Cosmic Trigger) then this pair outputs the Cosmic Trigger signal.

OUTPUT PAIR 1 (pins 3/6): If register 532 is set to 0 (Test Trigger) then this pair outputs the cosmic accept signal. If register 532 is set to 1 (Cosmic Trigger) then this pair outputs the Test Trigger signal.

TEST TRIGGER

The Test Trigger can be selected to be either a copy of the pipeline reset signal (a signal to the Trip-t chips to initialise the pipeline before the preamp integration/reset cycling begins) or a test pulse with programmable start and duration relative to the pipeline cycling. The functionality is selected and programmed in registers 523 and 535.