[ntp:hackers] u-blox reference clock driver

MLewis mlewis000 at rogers.com
Mon Aug 20 15:05:35 UTC 2018


Repeat. Didn't go out in text format.

On 20/08/2018 9:35 AM, MLewis via devel wrote:
> I believe that a kernal patch is not the correct way to do that. It's 
> too specific as it's only for some ublox modules.�
> I believe it should be a driver as a Loadable Kernel Module.
> This also allows people to easily modify the source to their own 
> needs, without needing to patch.
>
> I'm working on one now. Selectable triggers of Timemark 1, rising and 
> falling, and Timemark 2, rising and falling, providing up to four 
> timestamps for calculating four offsets, observing noise, etc., once 
> the timestamps are back in user space.
>
> A cycle of triggering timemarks (one cycle per second) can be initiated:
> - by the PPS so it's aligned with GPS UTC, or
> - it can run without PPS, aligned with system time TOS.
>
> Best guess, I've coded it to trigger timemarks at 250 ms, 415 ms, 580 
> ms and 745 ms, to keep those tasks spaced apart, yet away from the 
> module producing PPS at TOS and its epoch message delivery. We can see 
> results and modify when we'd like those to occur.
>
> I'm held up deciding on the method of sending messages for each 
> Trigger Timestamp from the kernel module back to user space.
> Looks like it should be a socket.
>
> Michael
>
> On 20/08/2018 9:13 AM, Udo van den Heuvel via devel wrote:
>>
>> How to get the timemark kernel patch into Linux?
>> Do we really need it? (can we work around it?)
>>
>> Udo 
>
>
>
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