Hi all, What's the current status of this? I'm also interested in adding PTP support to NuttX, especially on ESP32 if that's possible - I haven't done any research yet regarding the hardware capabilities of ESP32 in this matter.
As a first step I was thinking of adding support for the PTP daemon, as Alan suggested. Regards Robert On Fri, 9 Dec 2022 at 07:39, James Dougherty <jafr...@gmail.com> wrote: > Thanks Arie, > > Yes, very true, it depends on your application! > > My statement about what makes a good clock is very subjective. This > all depends on your application, your measurement and of course your > jitter. > > - For Wireless AV, a 10ms gps clock is fine. > - For Wireless Earbuds, a 10us clock is required with 1us phase max drift. > - For Photon measurements, you're in the nano/pico domain... > > Accuracy costs money, how well do you need to measure? > > So the message is to know your application! Your application will have > varying time requirements. The infrastructure and machinery for > relaying and exchanging time is all PTP provides as a tool. > > The 802.1AS spec specifies how to manage that clock across multiple > time domains. > > Related, know your latencies! > > https://gist.github.com/jboner/2841832 > > Best regards > -James > > > > On Thu, Dec 8, 2022 at 3:37 AM Arie de Muijnck <nu...@ademu.com> wrote: > > > Beware of that 1PPS signal. A few years ago I bought several GPS modules > > and compared the signals. Some differ by exactly 100ns (within 2ns, the > > accuracy of my scope) from others, and that is not the width of the > pulse, > > that is much wider, I compared only the edge that are comes close to the > > others. Maybe I will test again, have a 1 GHz LeCroy now, should be able > to > > do jitter measurements too. > > Oh, and yes, before someone asks: all antenna and scope cables were the > > same length... ;-) > > > > Arie > > > > > > On 2022-12-08 06:33, James Dougherty wrote: > > > Related to this, I have a GPS receiver generating PPS interrupts on > > SAME70. It would be a perfect GMC - Atomic clock sync! > > > I will look at this when I get a chance. I have a lot of upstream > > contributions from HW platforms I have done over the last 5 years or so > > with myself and others ... I need some time to > > > patch master on upstream -- something for 2023 and now that NuttX has > > graduated! Yay! > > > > > >
