Seems like we are getting closer.
The code I use to set the time source is
uhd_usrp_set_clock_source(usrp, "external", ALL_MBOARDS);
uhd_usrp_set_time_source(usrp, "_external_", ALL_MBOARDS);
Maybe it should not be _external_ by "external" without the "_"s? At least
on N200 _external_ works. I don't remember where I got the string, maybe
from reading the UHD sources or from the UHD documentation (this was a few
years ago).
Regarding the ref_locked: no, I am not using the external reference input
but the GPSDO. So I will remove the test on this in my code. On N200 it
seems okay to test because I think there it tests whether the PLL is locked
to whatever clock source is selected. Is that right?
Thanks, Sivan
On Thu, Jan 3, 2019 at 8:29 PM Marcus D. Leech <patchvonbr...@gmail.com>
wrote:
> On 01/03/2019 08:53 AM, Sivan Toledo wrote:
>
> Hundreds of milliseconds, which I think imply that either the PPS is
> arriving at a random time (not likely), or that the function that sets the
> time at the next PPS actually sets it immediately.
>
> The only thing i can think of is a setup error. Like not actually
> requesting the time source be set to "external" for the B200 case.
>
>
> Otherwise your assumptions about my setting is correct, an N200 and a B200
> each with its own Ettus GPSDO.
>
> I also noticed another thing that is strange, but maybe not the cause of
> my problem; the ref_locked sensor returns false on the B200 (even after I
> do all the procedure to set the clock at the next PPS) but true on the
> N200. Maybe the B200 simply does not have that hardware feature to check?
> Or does this indicates a problem?
>
> I think on the B200 "ref locked" refers to the external front-panel
> reference in. BTW if you are using the external REF-IN on a B200/B210
> you have to remove the internal GPSDO, due to electrical cross-talk on
> the REF lines.
>
>
>
> On Wed, Jan 2, 2019 at 7:53 PM Marcus D. Leech via USRP-users <
> usrp-users@lists.ettus.com> wrote:
>
>> On 01/02/2019 05:37 AM, Sivan Toledo via USRP-users wrote:
>> > Hi,
>> >
>> > I have a code that reads the GPS time and sets the time on the next
>> > PPS using uhd_usrp_set_time_next_pps. The code is based on advice from
>> > Ettus (we wait for PPS, wait 200ms, read the time, repeat 3 times, and
>> > then set the time correctly for the next PPS after checking that there
>> > are at least 200ms left in the second) and it works fine on N200 with
>> > GPSDO.
>> >
>> > The same code causes trouble on B200 with the TCXO based GPSDO. The
>> > GPS seems fine and we get a fix, and the code works fine, but the
>> > clocks are not synchronized with those of N200s.
>> >
>> > Is there a known problem with this function on N200s?
>> >
>> > Thanks, Sivan Toledo
>> >
>> Just to clarify the picture here, you have an N200 and a B200, each with
>> their own GPSDO. You're trying your best to synchronize them
>> using the PPS pulse from their respective GPSDOS?
>>
>> What scale is the lack-of-synchronization? Are we talking nanosecond,
>> microsecond, millisecond?
>>
>>
>>
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>
>
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