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Re: gpsd time service: PPS-synchronised SHM samples rare, both sources g
From: |
Gary E. Miller |
Subject: |
Re: gpsd time service: PPS-synchronised SHM samples rare, both sources gradually less and less frequent |
Date: |
Fri, 18 Sep 2020 15:53:57 -0700 |
Yo Marek!
On Fri, 18 Sep 2020 23:34:41 +0200
Marek Szuba <scriptkiddie@wp.pl> wrote:
> On 2020-09-18 21:36, Marek Szuba wrote:
>
> > Regarding the PPS signal, I have decided to bring out the big guns
> > and connected the receiver to an oscilloscope. Result - unless I
> > have wired something wrong, the PPS waveform has exactly the same
> > shape as what the receiver sends out on the TX line... That can't
> > be right, can it? The odd thing is, I have checked both the
> > computer-side connectors and (just to be extra sure) the pins of
> > the chip (whose label by the way says NEO-M8N after all) for short
> > circuits and there seem to be none. Something wrong with the
> > configuration of the TIMEPULSE signal?
>
> Yet another update: two hours ago I connected the same receiver (no
> factory reset, no reconfiguration) to the same system using a USB-TTL
> converter (with the PPS line connected to DCD),
You realize that the NEO-M8L does not output TTL levels? Trying to
use TTL levels will cause weird issues.
> fired up gpsd and
> configured chrony to listen to SHM 0 and SHM 1. Result: ever since the
> received got the 3D fix chrony has been getting samples for both NTP0
> and NTP1 every 4 seconds at most,
Typical of what you see with slight voltage mismatch.
Until you fix that, no point running any program that uses the gpio
or serial lines.
> Native TTL + pps-gpio, on two different systems: unusable.
As expected. No Raspberry Pi is TTL. In fact, TTL can burn out gpio
pins. I have done so.
You keep looking too far downstream, you problem is on your hardware inputs.
RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
gem@rellim.com Tel:+1 541 382 8588
Veritas liberabit vos. -- Quid est veritas?
"If you can't measure it, you can't improve it." - Lord Kelvin
pgpLcGlElzWcq.pgp
Description: OpenPGP digital signature
- gpsd time service: PPS-synchronised SHM samples rare, both sources gradually less and less frequent, Marek Szuba, 2020/09/14
- Re: gpsd time service: PPS-synchronised SHM samples rare, both sources gradually less and less frequent, Marek Szuba, 2020/09/16
- Re: gpsd time service: PPS-synchronised SHM samples rare, both sources gradually less and less frequent, Marek Szuba, 2020/09/18
- Re: gpsd time service: PPS-synchronised SHM samples rare, both sources gradually less and less frequent, Marek Szuba, 2020/09/18
- Re: gpsd time service: PPS-synchronised SHM samples rare, both sources gradually less and less frequent, Marek Szuba, 2020/09/18
- Re: gpsd time service: PPS-synchronised SHM samples rare, both sources gradually less and less frequent,
Gary E. Miller <=
- Re: gpsd time service: PPS-synchronised SHM samples rare, both sources gradually less and less frequent, Mike Simpson, 2020/09/19
- Re: gpsd time service: PPS-synchronised SHM samples rare, both sources gradually less and less frequent, Greg Troxel, 2020/09/19
- Re: gpsd time service: PPS-synchronised SHM samples rare, both sources gradually less and less frequent, Marek Szuba, 2020/09/21
- Re: gpsd time service: PPS-synchronised SHM samples rare, both sources gradually less and less frequent, Greg Troxel, 2020/09/21
- Re: gpsd time service: PPS-synchronised SHM samples rare, both sources gradually less and less frequent, Gary E. Miller, 2020/09/18
Re: gpsd time service: PPS-synchronised SHM samples rare, both sources gradually less and less frequent, Gary E. Miller, 2020/09/18