In message [EMAIL PROTECTED] David Miller
writes:
: Anyone know of a way to get a low cost port of some kind to to simple
: state change detection? The specific purpose is to time external events
: which are triggered by breaking an LED light beam. Millisecond resolution
: would be fine.
:
:
In message [EMAIL PROTECTED], Warner Losh writes:
If you have only 1 source, then you can use the ack line of the
parallel port and the ppi driver to get timestamped events. If you
have more than one, then you might be able to wire a simple latch to
the ACK line and sample of to 8 sources.
In message 60546.987709317@critter Poul-Henning Kamp writes:
: Use the pps driver and you get microsecond jitter with nanosecond
: resolution.
While I usually see microsecond jitter, I have seen it as high as a
few milliseconds when the interrupt load on the machine was high and
the cpu was
In message [EMAIL PROTECTED], Warner Losh writes:
In message 60546.987709317@critter Poul-Henning Kamp writes:
: Use the pps driver and you get microsecond jitter with nanosecond
: resolution.
While I usually see microsecond jitter, I have seen it as high as a
few milliseconds when the interrupt
In message 60866.987710568@critter Poul-Henning Kamp writes:
: The BIOS misuse of SMM mode can give you jitter in the 1msec range
: and there is not much you can do about it. I found out when I
: clocked a motherboard with a 14.318 derived from a Rb, and timed
: 1Hz pulses derived from a Cs.
In message 66167.987742147@critter Poul-Henning Kamp writes:
: Then the disk is probably running in PIO mode which thrashes your
: interrrupts.
That's likely right. This was a real low end machine, designed to be
smalffl and cheap.
: The pentium systems were much better about this.
:
:
Hi all;)
Anyone know of a way to get a low cost port of some kind to to simple
state change detection? The specific purpose is to time external events
which are triggered by breaking an LED light beam. Millisecond resolution
would be fine.
I was thinking of sampling the parallel port
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