[LinuxPPS] another refclock_nmea patch ([Bug 610] Generic NMEA GPS Receiver driver w/ PPS expects PPS after NMEA data)

[Rodolfo Giometti]

On Tue, Nov 06, 2007 at 05:58:45PM +0100, Udo van den Heuvel wrote:
> Rodolfo Giometti wrote:
> >>>> atom refclock code: (from atom_start)
> >> (...)
> >>>> So a device IS opened?!
> >>> You open the PPS device which is not the serial port, right? You do an
> >>> open() on /dev/pps*, don't you?
> >> For atom refclock we open the /dev/ppsX, yes.
> >> It is a serial port here.
> > 
> > Do you mean /dev/ppsX is a symlink to /dev/ttySX?
> 
> It was in the old days.
> Now it is a LinuxPPS device.

Ok, so you need the main device to open() /dev/ttySX and the alternate
device to open() /dev/ppsX.

> Regardless: why does atom on it's own not work?
> Why is `cat` needed? Or NMEA?

Because your PPS line is connetced with the serial line and it must be
opened in order to report PPS events.

This because you use a serial port as PPS source input device, if you
use a dedicated device, a CPU's GPIO for instance, you don't need this
dirty trick.

This can be avoided if you add to the ATOM refclock the possibility to
define a main and an alternate device as is in NMEA.

Ciao,

Rodolfo

-- 

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