1PPSCHECK(8)                   GPSD Documentation                   PPSCHECK(8)
2
3
4

NAME

6       ppscheck - tool to check a serial port for PPS
7

SYNOPSIS

9       ppscheck [-?] [--help] [--version] [-h] [-V] device
10

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.
17
18       ppscheck can run as a normal user, but that user must have permissions
19       to read the target device. Running as root will always work.
20
21       To check the first serial port do this:
22
23           ppscheck /dev/ttyS0
24
25       ppscheck is not intended for routine use, but rather for diagnostic
26       purposes. Once you have verified a particular device can output PPS
27       signals you will never need to use it again on that device.
28

OPTIONS

30       The program accepts the following options:
31
32       -?+, `+-h+, `+--help
33           Display help message and terminate.
34
35       -V+, `+--version
36           Dump version and exit.
37

ARGUMENTS

39       The device argument should be the pathname of a device. Such as
40       /dev/ttyS0 or /dev/pps0. It will be the device monitored.
41
42       Each output line is the second and nanosecond parts of a timestamp
43       followed by the names of the handshake signals then asserted. Off
44       transitions may generate lines with no signals asserted.
45
46       If you don’t see output within a second, use cgps or some other
47       equivalent tool to check that your device has a satellite lock and is
48       getting 3D fixes before giving up on the possibility of PPS.
49
50       Check your cable. Cheap DB9 to DB9 cables such as those issued with
51       UPSes often carry TXD/RXD/GND only, omitting handshake lines such as
52       DCD. Suspect this especially if the cable jacket looks too skinny to
53       hold more than three leads!
54
55       Most GPS that have built in USB do not support PPS. When in doubt,
56       contact the vendor for confirmation that your device does supply PPS.
57

RETURN VALUES

59       0
60           OK
61
62       1
63           if the device counld not be opened
64

SEE ALSO

66       gpsd(8)
67

RESOURCES

69       Project web site: https://gpsd.io/
70

COPYING

72       This file is Copyright 2013 by the GPSD project
73       SPDX-License-Identifier: BSD-2-clause
74

AUTHOR

76       Eric S. Raymond
77
78
79
80GPSD, Version 3.23.1              2021-09-03                       PPSCHECK(8)
Impressum