LinuxPPS wiki

Welcome to new LinuxPPS's wiki page!

LinuxPPS provides a programming interface (API) to define in the system several PPS sources.

PPS means “pulse per second” and a PPS source is just a device which provides a high precision signal each second so that an application can use it to adjust system clock time.

A PPS source can be connected to a serial port (usually to the Data Carrier Detect pin) or to a parallel port (ACK-pin) or to a special CPU's GPIOs (this is the common case in embedded systems) but in each case when a new pulse arrives the system must apply to it a timestamp and record it for userland.

Common use is the combination of the NTPD as userland program, with a GPS receiver as PPS source, to obtain a wallclock-time with sub-millisecond synchronisation to UTC.

More detailed information regarding PPS and LinuxPPS are available at Technical information page.

A LinuxPPS's mail list is available at http://www.linuxpps.org/cgi-bin/mailman/listinfo/discussions where you can send to your LinuxPPS related questions (please avoid asking about userland problems nor ntpd or chrony servers, etc.).

However before sending your questions to this list, please, take a look to the LinuxPPS FAQ page!

Projects using LinuxPPS:

• Dedicated Short Range Communications (DSRC) radio synchronization used by US-DOT's VII http://www.its.dot.gov/vii/ http://en.wikipedia.org/wiki/Vehicle_infrastructure_integration.

• Owens Valley Radio Observatory (OVRO / CARMA) correlator system.

• Raspberry Pi Stratum 1 NTP server with PPS. Accurate timekeeping at low cost.

• PPS-Client daemon for Raspberry Pi 2, 3 or 4 B or B+ or an AMD/Intel desktop system. Accurate time keeping precision of a timeline with a standard deviation of 0.5 microsecond and a typical time keeping accuracy of 2 microseconds.

If you have a project that is using LinuxPPS and you would like it to be shown here, please email giometti@ennenne.com.

Press talked about the LinuxPPS project on:

• Linux&C. issue 68 (year 11) at page 5 (Italian magazine).

• Linux Journal issue 185 (September 2009) at page 14.

• Kenji Hiranuma

• Folkert van Heusden

Other contributions can be done via PayPal.

• LANTIME M200/GPS from Meinberg.

• Many thanks to Meinberg for donating this new WEB space.

• Thanks to Andreas Puls for the LinuxPPS's logo.

• Thanks to World Time Solution for asking to me to do some improvements on LinuxPPS code.