1PPSCHECK(8) GPSD Documentation PPSCHECK(8)
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6 ppscheck - tool to check a serial port for PPS
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9 ppscheck [-h] [-V] device
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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
29 Display help message and terminate.
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31 -V
32 Dump version and exit.
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34 The "device" argument should be the pathname of a device. It will be
35 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 aserted.
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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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54 1 if the device counld not be opened. 0 otherwise
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57 gpsd(8).
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60 Eric S. Raymond <esr@thyrsus.com>.
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64The GPSD Project 28 Jul 2016 PPSCHECK(8)