Michael Smith wrote: > Hi Jan > I just want to clarify the meaning of the fields in the rtmac_waitinfo > structure because there are more than one way that these fields can be > interpreted. > > 1. The "cycle_no" field is a count of elementary cycles WITHIN a this > Sync frame (that runs from 1 to 100 or multiples of this) to indicate
Note the TDMA/RTmac terminology:
frame - an [Ethernet] packet
cycle - a set of frames transmitted periodically
> the progression within the frame. It is NOT the Cycle Number of the
> amount of frames sent on the LAN as indicated by the Cycle Number in
> the Synchronisation Frame header sent by an active master.
In fact, cycle_no is taken from the related Sync Frame field. But I'm
not explicitly referring to TDMA here as this interface shall be
independent of the RTmac discipline (at least as long as its periodic,
cycle-based).
>
> 2. The "cycle_start" time is the time as indicated by the local clock
> of the when the Sync of THIS frame was received. It is NOT the
> PREDICTED time of when the next Sync is SCHEDULED to happen.
No, it IS the scheduled cycle start, but that's an implementation detail
the interface shall hide. You should just take this date as the ideal
cycle start in local time. If that date was compensated to account for
master jitters (as with TDMA-v2) or not shall not matter here.
Jan
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