Dave Tweed wrote:
> My guess is that this additional time (8.7 seconds) simply represents
> the latency induced by the basic 1 ms USB frame period. Every
> transaction will experience a delay that averages 0.5 ms, or half the
> frame period.
> I would estimate that the process you describe above requires about
> 16k
> to 17k individual messages back and forth to the EasyProg. Does that
> sound about right?

There should have been at least 24K of them, plus a few extra, say around
25000.  Worst case you get one command and response per mS, but with the USB
otherwise unloaded the driver is allowed to use remaining bandwidth to go
back and allow devices that still have outstanding requests to use the bus
again.  In this case, the USB to serial adapter was the only device using
the USB at the time.  I imagine is uses bulk transfers, which would let it
essentially have the whole USB bandwidth when no other device requests it.


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