Christian Weisgerber <naddy@mips.inka.de> wrote:
> Stuart Henderson:
>
> > > I don't have any practical experience with nmea(4), but I'd like
> > > to draw attention to ldattach(8)'s -t option. Unless your receiver
> > > offers a pulse per second signal, you are limited to a very jittery
> > > timestamp from the serial telegram, mirroring udcf's fundamental
> > > problem.
> >
> > The problem isn't getting the pulses generated, it's getting
> > them hooked up to the computer and figuring out accurately
> > when they occurred.
>
> That's why I mentioned ldattach -t. We can timestamp on DCD or CTS
> transitions. On a real serial port, those will trigger an interrupt.
> That shouldn't be too bad.
Correct.
> I see that we also have code for timestamping on ucom(4), but since
> USB devices cannot directly generate interrupts and are in fact
> polled by the host controller, that will give poor results.
Correct.
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