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Cluster DAQ issues

When trying to implement software routines to use the cluster DAQ, I encountered a couple of issues, the first one requiring a fix:

  1. The FIFO_EMPTY is reset to 0 as soon as the S-bit monitor is itself reset. This means that one can start reading out events from the FIFO even before the module is triggered.

  2. This is likely not to be fixed in firmware, but it is worth mentioning that if the trigger (L1A or S-bit) rate is high (or one is unlucky), there could be "missing" data from the past. This has to be considered while looking at the readout window which may be incomplete.

Additionally, during the review of the code, I noticed that the wr_rst_busy signal of the XPM FIFO is left unconnected. From the documentation, it seems it should be used to avoid writing to the FIFO before the reset is complete.

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