[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 06:59:41PM +0100, Udo van den Heuvel wrote:
> Rodolfo Giometti wrote:
> > On Tue, Nov 06, 2007 at 05:58:45PM +0100, Udo van den Heuvel wrote:
> >> 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.
> 
> So this new LinuxPPS situation of always splitting data and PPS is not
> handy here. It requires extra work where it is not necessarily needed.
> 
> Only in the non-standard cases of GPIO, etc extra effort is required and
> only then changes to the standard habits should be needed.

This new situation is more general then before. Even in the very first
LinuxPPS version the PPS source and GPS data were splitted, the only
difference is that now a PPS source is represented by a char device.

> > 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.
> 
> So if LinuxPPS /dev/pps0 is for /dev/ttyS0 and we use atom, LinuxPPS
> does not (under water) open the serial port to make sure

This is not due the last LinuxPPS version, it was the same in the
past! Even with LinuxPPS 4.x and older you need to open() your serial
port in order to get PPS events.

So, the solution should be to provide a main and alternate device as
in NMEA.

Ciao,

Rodolfo

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