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electronics [2013/12/10 16:41]
pereira |
electronics [2013/12/10 20:12]
pereira [Busy circuit] |
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| ==== Busy circuit ==== | ==== Busy circuit ==== |
| 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. | As each controller and external data acquisition perform their readout sequence in parallel, they have different busy times. The busy circuit following the generation of raw triggers is mainly composed of a latch that is set by the "Raw trigger" signal, and cleared by the falling edge of the OR of the individual busy signals (Busy inputs) coming from individual crate controllers or other data acquisition systems. This way the "Live trigger" signal stays true as long as the longest busy signal. The "Live trigger" signal is therefore a "global busy" signal as well. In addition, the same busy signals of individual crate controllers or other data acquisition system are used to veto the "Raw trigger" signal and prevent the generation of a live trigger. This takes care of situations where separate triggers are generated for some of the crate controllers or other data acquisition systems (such as scaler readout sequences), during which no event readout sequence should be started. |
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| The busy circuit following the generation of raw triggers is mainly composed of a latch that is set by the "Raw trigger" signal, and cleared by the falling edge of the OR of the individual busy signals (Busy inputs) coming from individual crate controllers or other data acquisition systems. This way the "Live trigger" signal stays true as long as the longest busy signal. The "Live trigger" signal is therefore a "global busy" signal as well. In addition, the same busy signals of individual crate controllers or other data acquisition system are used to veto the "Raw trigger" signal and prevent the generation of a live trigger. This takes care of situations where separate triggers are generated for some of the crate controllers or other data acquisition systems (such as scaler readout sequences), during which no event readout sequence should be started. | |
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