"Minich, Raymond C" wrote:
> What happens if I have a rtl thread dumping characters into a FIFO, and my
> linux process doesn't query and empty the FIFO for a while, maybe for a long
> while. Will the FIFO fill up and crash the system?
No, but I think if you overrun it, you have a FIFO full of garbage and you need
to flush it before you read again.
>
> I want a rtlinux module to watch for the change of state of a digital input
> and then flag the change of state to the linux process and also communicate
> how much time has elapsed since the last change of state. Elapsed times
> could be anywhere from 1500 msec to 6000 msec. I figure using a FIFO to
> xmit a flag value (i.e. 0 or 1) and an elapsed time value (like the
> nanosecond clock's change in count).
>
> Am I on the right track?
>
If I understand you correctly, you want to monitor a external signal with
nanosecond resolution within a RT module.
If you want anything at all running in your system apart from your task,
you can't do it in a loop. The solution would be to periodically schedule
your task to sample the signal and detect a change. If say, 1 ms resolution
is enough for you, you can do it. I don't know what the limits are, but
nanoseconds is utopic.
Iwo
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