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.).

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.

If you have a project that is using LinuxPPS and you would like it to be shown here, please email mailto: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.