11 Jan
2006
11 Jan
'06
2:39 p.m.
Just a note on doing "read-ID" nonstop,
even on multi-tasking systems.
If you're processing interrupts yourself and the system has some sort of
guaranteed maximum latency for ISRs, you can fire out another Read ID
command from within the ISR. Since the 765 fires the interrupt as soon as
it reads an ID, there's a considerable amount of time to do this.
That was exactly my point - the analysis can be done in the driver (and
hence the interrupt handler) without much trouble, however on a multitasking
system, you cannot guarantee the real time requirement at the application
level. Using the interrupt from one event to start the next event aliminates the
task priority system entirely, and the only variability you may encounter is
the interrupt latency, which would usually be acceptably low (unless you have
other processor intensive interrupts, or mis-behaving applications which
disable interrupts for extended periods of time, it should easily be within a
sector time.
--
dave04a (at) Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
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