The interface between the laser control and the Trigger andDAQ systems is based on a well defined sequence of signalsto perform an exact and unambiguous synchronization to thephysics events. This will consider the different time and dataformats for several operation modes.A.TheFunctionalitiesThe main operation modes of the laser control systemprovide:•time reference signal for reset, synchronization and ini-tialization of the detector and the electronics;•light pulse generation at programmable frequency;•hit patterns generated randomically according an in-tegral distribution function set by a software toolboth for physics event simulation and for detec-tor/DAQ/electronics test and characterization;All the configurable parameters can be defined in an array ofregisters; a software interface allows the setup remotely.B.TheArchitectureThe system has been realized by using an hybrid platformwith FPGA board and ARM-based processor. A schematicblock diagram of the laser control is shown in Fig. 2.The interface with the trigger system is implemented intheT riggerblock where an external trigger defines thebeginning of the laser sequence. TheLaserblock drives thelaser device signals.The operation modes are managed in theLaser Control M odeblock where it is possible toselect for different modes and configure the correspondentparameters for trigger distribution.C.TheOperationModesNow a short discussion is reported on these two main usesof the laser control system.The “on-line” calibration mode operating during the physicsruns is essentially based on a programmed number of pulsesissued during an enable gate convenientely delayed withrespect the external trigger. Thewidth of the enable signal andthe number of pulse in the window are programmed definingthe pulse rate. The time duration of the enable gate spansfrom fewμstoms; the programmable pulse rate ranges fromhundreds of Hz to MHz.The “off-line” calibration modeused principally within adedicated calibration run is based on the interaction betweensoftware and hardware components. Essentially a softwareprocess builds a frame containing all the time hit sequence (inan enable gate) and sends it to the hardware block for the pulsegenerations. In fact, on the external trigger a local time counterstarts and everyΔt time step (bin size of the distribution) acomparison between the local timeregister and the pointedtime record, extracted from the frame is carried out. In caseof a match, the digital comparator outputs a laser pulse. Thena new hit time word is extracted and the comparison processcan go ahead until the end of frame is detected