[LinuxPPS] parallel port pps info

[Rodolfo Giometti]

On Sun, Jul 06, 2008 at 04:05:27PM -0700, gnu not unix wrote:
> Hi Folks--
> 
> I have pps out of a Spectracom Netclock/2, a radio clock that
> uses the LF signal at 60 KHz with a time code (known here as WWVB).
> So I set up the ttl level pps output of this clock as a feed for the
> parallel port input to the linuxpps host. The syslog shows this entry
> when I used the lp driver:
> 
> Jul  6 11:37:38 nimbus kernel: 
>      lp0: using parport0 (interrupt-driven).
> 
> Jul  6 11:37:38 nimbus kernel: 
>      new PPS source parport0 at ID 1
> 
> Jul  6 11:37:38 nimbus kernel: 
>      parport_pc parport_pc.888: PPS source #1 "/dev/lp0" added
> 
> And the /dev/pps1 entry also shows up. This fed a pps signal ok,
> except that it seemed to override the GPS pps signal, so I unloaded
> the lp module and replaced it with the ppsdev module so I could
> run the userspace shm pps program.
> 
> The shm program worked fine, however it seemed to perturb the linuxpps
> badly. The offset shown in the shm program became the offset shown
> by ntpd. This is very confusing, I had not configured a shm driver
> in ntpd, and I had unloaded the lp module, so I can't even imagine
> how the ntpd could be affected. Even after I stopped the shm
> program the offset seemed to still be tweaked by the parallel port
> input. Only after i *physically disconneced* the cable does the
> GPS pps signal take over again
> 
> It feels like I've really Lost It (cough, american slang for 
> flipping out, losing your marbles, few cards short of a full deck,
> etc etc).
> 
> Has anyone else tried multiple linuxpps pps inputs? 

I suggest you to the the PPS line alone before... can you use ppstest
on your PPS parport line?

> //Steve
> making Extra Strong coffee now

:)

Ciao,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail: giometti at enneenne.com
Linux Device Driver                          giometti at linux.it
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