On Wed, Jul 29, 2015, at 04:40 PM, Richard Cochran wrote: > On Wed, Jul 29, 2015 at 02:46:34PM +0200, Juan Solano wrote: > > I am learning about PTP and doing tests on 2 Beaglebone Blacks running a > > recent stable linux (v3.18.16) with disabled dynamic ticks. They support > > hardware timestamping and I have synchronized the system clocks to the > > PHC. My logs show what seem to be good values: > > ... > > > However, when comparing the PPS GPIO outputs with an oscilloscope I can > > see them varying in a range of +- 800 ns. > > The CPTS in the AM335x does not have any hardware output signals. The > PTP clock cannot be adjusted because of silicon bugs, so we leave the > hardware clock free running and use a software clock as a work around. > > > Can anybody point me at something obvious that I am missing or how to > > investigate further? > > Tell us how you are generating the PPS.
Oops! time to ditch the BBB then. I have written a PPS generator driver through GPIO: https://github.com/jsln/pps-gen-gpio Do you know of a cheap SBC we can use that supports HW timestamp? Has anybody had success with Atmel SAMA5D3 chips? Thanks, Juan. ------------------------------------------------------------------------------ _______________________________________________ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
