[LinuxPPS] LinuxPPS for Raspberry Pi?

[folkert]

Maybe you can draw schematics for connecting the garmin to the RPI?
I can solder but I cannot figure out how to alter the voltage levels or
inverting.
thanks

On Sat, Jan 26, 2013 at 08:16:52PM -0500, tlhackque wrote:
> I've just acquired a Raspberry Pi (RPI), and have attached a Garmin
> GPS18x-LVC (FW 3.80) to the serial port and the PPS output to GPIO4
> (via an inverting level converter).  It's a nice package, except for
> not having a local clock).
> 
> I have successfully configured ntpd (4.2.6p5) to see it as a NEMA
> clock (right now it's noselect while I measure the serial data
> offset).
> 
>      remote           refid      st t when poll reach   delay offset
> jitter
> ==============================================================================
>  127.127.20.1    .GPS.            0 l   55   64  377    0.000
> -682.66   5.112
> 
> For the next step, PPS - some questions:
> 
> 1. Has anyone tread this road already?  I've seen several
> inquiries/aborted attempts on the web, but no successes.
> 
> 2. The RPI kernel is Debian based.  It has sysfs gpio support
> (/sys/class/gpio), and from the shell, I can see the pin toggling if
> I export the pin.
> 
>      How do I tell if the kernel has PPS support compiled-in?
> 
> 3. Do I need compiled-in kernel support, or can PPS just be
> modprobed in?  (It looks like compiling the kernel on RPI is a major
> undertaking  - http://elinux.org/RPi_Kernel_Compilation.)  If the
> latter, how do I build the modules?
> 
> 4. What's the minimal support that we could try to get the RPI
> developers to include in the distributed kernel to enable PPS, or at
> least make it less of a project to build?
> 
> I'd have to native (on the RPI) build anything for this project
> ('disk' is a 16GB SD flash card), so any help would be appreciated.
> 
> Thanks.
> 
> -- 
> This communication may not represent my employer's views,
> if any, on the matters discussed.
> 
> 
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Folkert van Heusden

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