here they point out to pps_out hardware solution for Jetson boards https://forums.developer.nvidia.com/t/jetson-xavier-hardware-pps-out/124003/16
On Wed, Jun 24, 2020 at 3:40 PM Andrey Volodin <andrevolo...@gmail.com> wrote: > "we need only microsecond accuracy" > the Jetson board has SensorProcessingEnngine: > "provide a built-in Cortex-R5 micro-controller within an always-on power > domain also known as Sensor Processing Engine (SPE). Example uses include > sensor data processing, wake up management, UAV, and robotics. > > This source file will aid in the development of FreeRTOS-based firmware > for SPE" > > from the SPE documentation > > On Wed, Jun 24, 2020 at 3:31 PM Richard Hill <plo...@gmx.de> wrote: > >> Some boards (but not yours) have PPS-in direct timestamping. Some iMX6s >> have this. You’ll still need to mod the driver as it only handles PPS-out, >> but >> >> it’s < 25ns accurate once running. >> >> >> >> There’s just far too much latency for PPS-in via GPIO to be useful. >> >> >> >> Richard H >> >> >> >> >> >> *From:* Andrey Volodin [mailto:andrevolo...@gmail.com] >> *Sent:* Mittwoch, 24. Juni 2020 16:26 >> *Cc:* linuxptp-users@lists.sourceforge.net >> *Subject:* Re: [Linuxptp-users] Fwd: Fwd: adding precision with PPS with >> PTP [linuxptp] on nvidia Jetson arm aarch64 device >> >> >> >> Dear Richard, >> >> Thank you for your response. >> >> How do we discipline the clocks to the global GPS time? using the >> software time stamping from /dev/pps0? using linuxptp scenario defined >> previously? >> >> How to implement a better source for PTP GM? Do you have any exact >> suggestions? >> >> Regards, >> >> Andrei >> >> >> >> On Wed, Jun 24, 2020 at 2:47 PM Richard Cochran <richardcoch...@gmail.com> >> wrote: >> >> On Wed, Jun 24, 2020 at 12:48:45PM +0000, Andrey Volodin wrote: >> > The initial host date/time in the example is set manually. >> > probably /dev/pps0 can be used at the host side to set the time/date >> more >> > accurately than using manual method defined above? so that the time >> > sdynchronized with the dup will come from the GPS pps timepulse [ >> sourced >> > in Ardusimple SimpleRT2K] ? >> >> So you want to discipline your two PHC clocks to the global GPS time? >> >> What are you trying to do? >> >> Remember that /dev/pps0 is using software time stamping, and as such >> it makes a relatively poor source for a PTP GM. >> >> Thanks, >> Richard >> >>
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