[LinuxPPS] Using LinuxPPS for Event Counting

[Bernhard Schiffner]

On Tuesday 30 September 2008 03:57:17 Thiago Tiedtke wrote:
> Hi everybody,
>
> I´m using the LinuxPPS with ntp to adjust a pc clock, using the DCD pin to
> catch the PPS signal from gps, and NMEA messages from a GPS Novatel DL4
> ...and this is task is ok, my question is:
>
> I can use the LinuxPPS to "poll" other type of events, e.g., a interruptor,
> or a photodiode ??

Absolutely.
Linuxpps can do this job with a high confidence.
(But don't confuse software in higher levels like ntpd with such a signal.)

> By fact, i'm doing these tests, "catching" events with 1/1000s of
> duration...but without the regularity from signal PPS (e.g. at each 1 sec
> +/- 20ns) from a GPS device....

A ms doesn't hurd anybody on "normal" hardware.
But keep in mind that the interrupts (slope H/L, slope L/H) can be fired in a 
very close manner. A PC can be blocked for the same interrupt about 50µs. 

> This can be applied? What the "quality" of timestamp of each event?
Depends on your scope.
As deeper you look as more factors will rise.
Can you provide more details please?
(All the timing is done on trust. There is only very little opportunity to 
verify any given statement. This is because all this is about consuming 
something, but not providing.)

>
> Thanks for any help
>
> Thiago Tiedtke dos Reis

Bernhard