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====== Electronics ====== | ====== Electronics ====== | ||
+ | * [[Electronics# | ||
+ | * [[Electronics# | ||
+ | * [[Electronics# | ||
+ | * [[Electronics# | ||
- | ===== General description ===== | ||
- | The trigger of the S800 offers the possibility to combine the S800 trigger with triggers from other detectors or arrays in order to form coincidences. This is often a mandatory requirement when the trigger rate of the S800 alone (S800 singles) is too high for the data acquisition and the resulting dead time is prohibitive. | ||
- | Because the USB-based S800 data acquisition uses independent crate controllers that perform the readout in parallel, time stamping and busy schemes are incorporated in the trigger to synchronize events and insure no trigger is generated while readout sequences are being executed. Because of this modularity, adding an external data acquisition system (typically from an external detector), is straightforward. | + | ===== Crate Configuration ===== |
+ | ===== Inventory Modules ===== | ||
+ | ===== Electronic Diagrams ===== | ||
+ | * Main Electronic Diagram | ||
+ | * {{: | ||
+ | * {{: | ||
+ | * {{: | ||
+ | * {{: | ||
+ | * {{: | ||
- | ===== Schematics ===== | ||
- | Thanks to FPGA technology, the trigger logic is remotely controllable via a GUI which is shown below. | ||
- | {{: | + | ===== Electronic Diagram |
- | + | ===== Trigger | |
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- | The two main trigger sources are labeled " | + | |
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- | Time stamping scheme================= | + | |
- | The S800 trigger provides a vetoed 10 MHz clock signal used for time stamping (an external clock can also be used). The clock is inhibited by a " | + | |
- | Busy scheme | + | |
- | As each controller and external data acquisition perform their readout sequence in parallel, they have different busy times. The global busy signal is formed by a logical OR of all busy signals. To eliminate delays caused by the cables routing the individual signals, the S800 trigger uses local latches that are set by the trigger signal and reset by the individual end-of-event signals. The length of the global busy is then determined by the slowest readout sequence. | + | |
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- | Trigger box | + | |
- | In addition to the singles and coincidence triggers, two separate inputs called " | + | |
- | Busy circuit | + | |
- | The busy circuit following the generation of raw triggers is mainly composed of a latch that is set by the "Raw trigger" | + | |
- | Gate generation | + | |
- | All digitizer gates and start signals are derived from the live trigger signal, with the exception of the QDC gate which is directly generated from the S800 source signal. The reason is to avoid long analog delays on the scintillator signals. A fast clear circuit is provided to clear the QDC if no valid trigger was generated. | + | |
- | Inspect channels | + | |
- | A set of four inspect channels are patched out to the Data-U6 panels. Each channel can be assigned to any connection drawn on the GUI, thereby providing a convenient way to diagnose and adjust the timings at each step of the trigger circuit. | + | |
- | Time stamping | + | |
- | As the S800 USB-based data acquisition uses independent crate controllers, | + | |
- | The trigger module FPGA configuration contains a 64 bit counter which is latched by the "Live trigger" | + | |
- | The time stamping clock is available as an output that can be distributed to other time stamp modules, such as the one located in the S800 VME crate, or in other data acquisition systems coupled to the S800. | + | |
- | VME time stamp XLM72 module | + | |
- | The time stamp module is implemented in a XLM72 (SpartanXL) FPGA. This section describes the firmware used to configure this module into a 64 bit latched time stamp module. The inputs are the following: | + | |
- | E1: time stamp clock input | + | |
- | E2: latch input | + | |
- | E3: clear input | + | |
- | The clear can be done via software as well, and is usually done that way. | + | |
- | The schematics of the firmware can be is available. | + | |
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- | Configuration for S800 in tandem with other detectors | + | |
- | In its standard configuration, | + | |
- | To incorporate an external detector in the S800 trigger logic, the same busy and end-of-event signals are required from its data acquisition system. This is to ensure that no live trigger signal is generated when any of the partners is busy or still processing an event. The 5 signals necessary between the S800 trigger and an external data acquisition system are the following: | + | |
- | • Raw trigger from external detector to Secondary source | + | |
- | • Live trigger from S800 trigger to external data acquisition (trigger input) | + | |
- | • Time stamp clock from S800 trigger to external data acquisition (time stamp input) | + | |
- | • End-of-event from external data acquisition to S800 trigger | + | |
- | • Busy from external data acquisition to S800 trigger | + | |