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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
chrony servers, etc.).