Re: [Linuxptp-users] grandmaster with an H/P 3805A GPS disciplined osc

[David G. <dav...@po...>]

On 08/20/2013 11:09 PM, Richard Cochran wrote:
> On Wed, Aug 21, 2013 at 07:47:54AM +0200, Richard Cochran wrote:
>> On Tue, Aug 20, 2013 at 02:00:05PM -0700, David Gravereaux wrote:
>>> I was wondering if I use NTPd for controlling the GPS radio with its
>>> built-in driver for it along with the PPS signal on the comport as the
>>> DCD line
>>> <http://support.ntp.org/bin/view/Support/Z3801AReceiverModifications>,
>>> would this share the same counter for PTP?
>>
>> This setup will synchronize the Linux system time to the external
>> Z3801A box using a PPS signal. You could use ptp4l with software time
>> stamping and the 'free_running' option to serve this time to your
>> network.
> 
> But you have an Intel i210, right?
> 
> So it would be even better to feed the PPS from the Z3801A into one of
> the i210's SDP pins. (Be careful with the signal conditioning, SDP is
> CMOS directly to the chip.)
> 
> I posted a igb patch on netdev to enable the SDP functions. This was
> not accepted into mainline (I'll have to make minor changes first),
> but it does work. You can patch your kernel with it.
> 
> Then you can use the i210's external time stamps of the PPS to
> discipline the i210's clock. You will have to write some code, but
> you can re-use phc2sys and the testptp program, as they have most of
> what you need.
> 
> The PPS will give you the phase offset from the full second, and you
> can read the time and date from the serial port.
> 
> Good luck,
> Richard
> 


Awesome!  I thought there might have been hardware support in the card,
but wasn't sure.  Let me meditate on this for a bit.  Writing C is what
I live for.  I won't get the radio for a couple weeks yet.

I want to get a leg-up on this "stock" workstation if possible before
moving to PC/104e

-- 
David Gravereaux <dav...@po...>