1GPSCTL(1) GPSD Documentation GPSCTL(1)
2
6 gpsctl - control the modes of a GNSS receiver
7
9 gpsctl [OPTIONS] [serial-port]
10 gpsctl -h
12 gpsctl -V
14
16 gpsctl can switch a dual-mode GNSS receiver between NMEA and
17 vendor-binary modes. It can also be used to set the device baud rate.
18 Note: Not all devices have these capabilities.
19 If you have only one GNSS receiver attached to your machine, and gpsd
21 is running, it is not necessary to specify the device; gpsctl does its
22 work through gpsd, which will locate it for you.
23 When gpsd is running, gpsctl may be run as any user, or as root.
25 When gpsd is not running, the device specification is required, and you
27 will need to be running as root or be a member of the device’s owning
28 group in order to have write access to the device. On many Unix
29 variants the owning group will be named 'dialout'.
30 Running under sudo will cause some loss of functionality.
32
34 The program accepts the following options:
35 -?, -h, --help
37 Display program usage and exit.
38 -b, --binary
40 Put the GNSS receiver into native (binary) mode.
41 -c RATE, --rate RATE
43 Change the receivers’s cycle time. Units are seconds. Note, most
44 receivers have a fixed cycle time of 1 second.
45 -D LVL, --debug LVL
47 Set level of debug messages.
48 -e, --echo
50 Generate the packet from any other arguments specified and ship it
51 to standard output instead of the device. This switch can be used
52 with the -t option without specifying a device. Note: the packet
53 data for a binary prototype will be raw, not ASCII-ized in any way.
54 -f, --force
56 Force low-level access (not through the daemon).
57 -l, --list
59 List a table showing which option switches can be applied to which
60 device types, and exit.
61 -n, --nmea
63 Put the GNSS receiver into NMEA mode.
64 -r, --reset
66 Reset the GNSS receiver. Device port and type must be specified.
67 -R, --rmshm
69 Remove the GPSD shared-memory segment used for SHM export. This
70 option will normally only be of interest to GPSD developers.
71 -s SPEED, --speed SPEED
73 Set the baud rate at which the receiver emits packets.
74 Use the -s option with caution. On USB and Bluetooth GPSes it is also
76 possible for serial mode setting to fail either because the serial
77 adaptor chip does not support non-8N1 modes or because the device
78 firmware does not properly synchronize the serial adaptor chip with the
79 UART on the GPS chipset when the speed changes. These failures can hang
80 your device, possibly requiring a GPS power cycle or (in extreme cases)
81 physically disconnecting the NVRAM backup battery.
82 -t TYPE, --type TYPE
84 Force the device type.
85 -T TIMEOUT, --timeout TIMEOUT
87 Change the sampling timeout. Defaults to 8 seconds, which should
88 always be sufficient to get an identifying packet from a device
89 emitting at the normal rate of 1 per second.
90 -V, --version
92 Display program version and exit.
93 -x STR, --ship STR
95 Send a specified control string to the GPS, gpsctl will provide
96 packet headers and trailers and checksum as appropriate for binary
97 packet types, and whatever checksum and trailer is required for
98 text packet types. (You must include the leading $ for NMEA
99 packets.) When sending to a UBX device, the first two bytes of the
100 string supplied will become the message class and type, and the
101 remainder the payload. When sending to a Navcom NCT or Trimble TSIP
102 device, the first byte is interpreted as the command ID and the
103 rest as payload. When sending to a Zodiac device, the first two
104 bytes are used as a message ID of type little-endian short, and the
105 remainder as payload in byte pairs interpreted as little-endian
106 short. For all other supported binary GPSes (notably including
107 SiRF) the string is taken as the entire message payload and wrapped
108 with appropriate header, trailer and checksum bytes. C-style
109 backslash escapes in the string, notably \xNN for hex, will be
110 interpreted; additionally, \e will be replaced with ESC. This
111 switch implies -f.
112 The argument of the forcing option, -t, should be a string which is
114 contained in exactly one of the known driver names; for a list, do
115 gpsctl -l.
116 Forcing the device type behaves somewhat differently depending on
118 whether this tool is going through the daemon or not. In high-level
119 mode, if the device that daemon selects for you doesn’t match the
120 driver you specified, gpsctl exits with a warning. (This may be useful
121 in scripts.)
122 In low-level mode, if the device identifies as a Generic NMEA, use the
124 selected driver instead. This will be useful if you have a GPS device
125 of known type that is in NMEA mode and not responding to probes. (This
126 option was originally implemented for talking to SiRFStar I chips,
127 which don’t respond to the normal SiRF ID probe.)
128 If no options are given, the program will display a message identifying
130 the GPS type of the selected device and exit.
131 Reset (-r) operations must stand alone; others can be combined.
133 Multiple options will be executed in this order: mode changes (-b and
134 -n) first, speed changes (-s) second, and control-string sends (-c)
135 last.
136
138 By setting the environment variable GPSD_SHM_KEY, you can control the
139 key value used to designate the shared-memory segment removed with the
140 -R option. This will be useful mainly when isolating test instances of
141 gpsd from production ones.
142
144 gpsctl /dev/ttyUSB0
145 Attempt to identify the device on USB serial device 0. Time out
146 after the default number of seconds. Adding the -f will force
147 low-level access and suppress the normal complaint when this tool
148 can’t find a GPSD to work through.
149 gpsctl -f -n -s 9600 /dev/ttyUSB0
151 Use low-level operations (not going through a gpsd instance) to
152 switch a GPS to NMEA mode at 9600bps. The tool will identify the
153 GPS type itself.
154
156 SiRF GPSes can only be identified by the success of an attempt to flip
157 them into SiRF binary mode. Thus, the process of probing one of these
158 running in NMEA will change its behavior.
159 Baud rate and mode changes work in direct mode but are not reliable in
161 client mode. This will be fixed in a future release.
162
164 0
165 on success.
166 1
168 on failure
169
171 gpsd(8), gpsdctl(1), gps(1), ubxtool(1), zerk(1)
172
174 Project web site: https://gpsd.io/
175
177 This file is Copyright 2013 by the GPSD project
178 SPDX-License-Identifier: BSD-2-clause
179
181 Eric S. Raymond
182GPSD, Version 3.24 2021-09-20 GPSCTL(1)