1PPSCHECK(8)                   GPSD Documentation                   PPSCHECK(8)
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NAME

6       ppscheck - tool to check a serial port for PPS
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SYNOPSIS

9       ppscheck [-?] [--help] [--version] [-h] [-V] device
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DESCRIPTION

12       ppscheck watches a specified serial port for transitions that might be
13       PPS. It looks for changes in handshake lines CD, RI, and CTS by running
14       ioctl(...., TIOCMIWAIT, ...) in a loop. When it sees a state change it
15       emits a timestamped line of output dumping the state of the handshake
16       signals. It's useful for checking whether a device is emitting PPS.
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18       To check the first serial port do this:
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20           ppscheck /dev/ttyS0
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22       ppscheck is not intended for routine use, but rather for diagnostic
23       purposes. Once you have verified a particular device can output PPS
24       signals you will never need to use it again on that device.
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26       The program accepts the following options:
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28       -?, -h, --help
29           Display help message and terminate.
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31       -V, --version
32           Dump version and exit.
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34       The "device" argument should be the pathname of a device. Such as
35       /dev/ttyS0 or /dev/pps0. It will be the device monitored.
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37       Each output line is the second and nanosecond parts of a timestamp
38       followed by the names of the handshake signals then asserted. Off
39       transitions may generate lines with no signals asserted.
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41       If you don't see output within a second, use gpsmon or some other
42       equivalent tool to check that your device has a satellite lock and is
43       getting 3D fixes before giving up on the possibility of PPS.
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45       Check your cable. Cheap DB9 to DB9 cables such as those issued with
46       UPSes often carry TXD/RXD/GND only, omitting handshake lines such as
47       DCD. Suspect this especially if the cable jacket looks too skinny to
48       hold more than three leads!
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50       Most GPS that have built in USB do not support PPS. When in doubt,
51       contact the vendor for confirmation that your device does supply PPS.
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RETURN VALUES

54       1 if the device counld not be opened. 0 otherwise
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SEE ALSO

57       gpsd(8).
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AUTHOR

60       Eric S. Raymond <esr@thyrsus.com>.
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64The GPSD Project                5 December 2020                    PPSCHECK(8)