[LinuxPPS] Trying to get parallel port client working on 2.6.26

[Bernhard Schiffner]

On Friday 19 September 2008 19:54:17 Paul Simons wrote:
> I have an old TrueTime 4<mumble>-DC that uses a GPS to GOES converter.
> I've been a member of pool.ntp.org for some time now, and I'd like to get
> more accurate and get PPS running.  This clock puts out a TTL PPS.  First
> question:
>
> I notice that people seem to convert from TTL to RS232 and then use the
> serial port.  Why is that?
>
> I am using the parallel port (pin 10 - ACK, pin 24 - ACK ground) and just
> going straight TTL.  Everything seems to register fine:
>
> dmesg | grep -i pps
> LinuxPPS API ver. 1 registered
> PPS line discipline registered
> new PPS source parport0 at ID 0
> parport_pc 00:08: PPS source #0 "/dev/lp0" added
> dmesg | grep -i parport
> parport_pc 00:08: reported by Plug and Play ACPI
> parport0: PC-style at 0x378 (0x778), irq 7, dma 3
> [PCSPP,TRISTATE,COMPAT,ECP,DMA]
> lp0: using parport0 (interrupt-driven).
> new PPS source parport0 at ID 0
> parport_pc 00:08: PPS source #0 "/dev/lp0" added
>
> However, no joy:
>
> ./ppstest /dev/pps0
> trying PPS source "/dev/pps0"
> found PPS source "/dev/pps0"
> ok, found 1 source(s), now start fetching data...
> time_pps_fetch() error -1 (Connection timed out)
> time_pps_fetch() error -1 (Connection timed out)
> time_pps_fetch() error -1 (Connection timed out)
> ^C
>
> I am using a Debian kernel:
>
> uname -a
> Linux mercury 2.6.26.simonet #1 SMP Sat Sep 13 11:10:50 PDT 2008 i686
> GNU/Linux
>
> and I am using the ntp-pps-2.6.26.diff patch.
>
> I'd like to see this working as a first step.  Is that reasonable?  Should
> I start sprinkling printks to see where I'm going wrong?  I hooked up a
> digital multimeter and it twitches; should I get some sort of LED?  Should
> I convert to RS232 signaling?
>
> Okay, I'll stop now.

All Hardware et. al. sounds good. 

If you are sure (and you are) to have a good signal at the ACK-pin, then 
the "only" problem is to set the parport interrupt enabled.

I myself tried the same and didn't figure out, how to do this.
For the same purpose at the serial port you have "setserial"...

Normal pc parport is at IRQ 7. cat /proc/interrupts can tell you their 
respective occurence.

Good luck!

Benrhard

If you found a way, can you give a feedback here please?