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Old March 29th, 2007   #1
Dan Scheurell
Junior Member
Join Date: Mar 2007
Location: Middleton, Wisconsin, USA
Posts: 4
Default Exceeding MAB time

RDM imposes a restriction on the MAB time (88 us) that is new since DMX. Some combinations of external UART and CPU may have difficulty guaranteeing that time (if, for instance, interrupt priorities are relatively fixed and a higher priority interrupt preempts and takes its sweet time.)

It seems like the restriction is based on performance considerations, to prevent the line from laying around idle for too long. In that case, exceeding the spec a bit (say for about 40 us) may not be a tragedy? I can imagine that some RDM devices could assume that the controller has gone, but I'm wondering if, in general, the extra time would go unnoticed.

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