gpsctl(1) GPSD Documentation gpsctl(1)
NAME
gpsctl - control the modes of a GNSS receiver
SYNOPSIS
gpsctl [OPTIONS] [serial-port]
gpsctl -h
gpsctl -V
DESCRIPTION
gpsctl can switch a dual-mode GNSS receiver between NMEA and
vendor-binary modes. It can also be used to set the device baud rate.
Note: Not all devices have these capabilities.
If you have only one GNSS receiver attached to your machine, and gpsd is
running, it is not necessary to specify the device; gpsctl does its work
through gpsd, which will locate it for you.
When gpsd is running, gpsctl may be run as any user, or as root.
When gpsd is not running, the device specification is required, and you
will need to be running as root or be a member of the device's owning
group in order to have write access to the device. On many Unix variants
the owning group will be named 'dialout'.
Running under sudo will cause some loss of functionality.
OPTIONS
The program accepts the following options:
-?, -h, --help
Display program usage and exit.
-b, --binary
Put the GNSS receiver into native (binary) mode.
-c RATE, --rate RATE
Change the receivers's cycle time. Units are seconds. Note, most
receivers have a fixed cycle time of 1 second.
-D LVL, --debug LVL
Set level of debug messages.
-e, --echo
Generate the packet from any other arguments specified and ship it to
standard output instead of the device. This switch can be used with
the -t option without specifying a device. Note: the packet data for
a binary prototype will be raw, not ASCII-ized in any way.
-f, --force
Force low-level, direct, access (not through the daemon).
-l, --list
List a table showing which option switches can be applied to which
device types, and exit.
-n, --nmea
Put the GNSS receiver into NMEA mode.
-r, --reset
Reset the GNSS receiver. Device port and type must be specified.
-R, --rmshm
Remove the GPSD shared-memory segment used for SHM export. This
option will normally only be of interest to GPSD developers.
-s SPEED, --speed SPEED
Set the baud rate at which the receiver emits packets.
Use the -s option with caution. On USB and Bluetooth GPSes it is also
possible for serial mode setting to fail either because the serial
adaptor chip does not support non-8N1 modes or because the device
firmware does not properly synchronize the serial adaptor chip with the
UART on the GPS chipset when the speed changes. These failures can hang
your device, possibly requiring a GPS power cycle or (in extreme cases)
physically disconnecting the NVRAM backup battery.
-t TYPE, --type TYPE
Force the device type.
-T TIMEOUT, --timeout TIMEOUT
Change the sampling timeout. Defaults to 8 seconds, which should
always be sufficient to get an identifying packet from a device
emitting at the normal rate of 1 per second.
-V, --version
Display program version and exit.
-x STR, --ship STR
Send the specified control string to the GNSS receiver. C-style
backslash escapes in the string are decoded. Use \xNN for hex, \e
will be replaced with ESC.
In normal mode, through _gpsd_, the decoded string is passed through,
unchanged top _gpsd_ which in turns sends it to the receiver. Headers,
checksums, and suffffices must be provided.
In low-level, (direct) mode *gpsctl* will provide packet headers and
trailers and checksum as appropriate for binary packet types, and
whatever checksum and trailer is required for text packet types.
(You must include the leading $ for NMEA packets.) When sending to a
UBX device, the first two bytes of the string supplied will become
the message class and type, and the remainder the payload. When
sending to a Navcom NCT or Trimble TSIP device, the first byte is
interpreted as the command ID and the rest as payload. When sending
to a Zodiac device, the first two bytes are used as a message ID of
type little-endian short, and the remainder as payload in byte pairs
interpreted as little-endian short. For all other supported binary
GPSes (notably including SiRF) the string is taken as the entire
message payload and wrapped with appropriate header, trailer and
checksum bytes.
The argument of the forcing option, -t, should be a string which is
contained in exactly one of the known driver names; for a list, do gpsctl
-l.
Forcing the device type behaves somewhat differently depending on whether
this tool is going through the daemon or not. In high-level mode, if the
device that daemon selects for you doesn't match the driver you
specified, gpsctl exits with a warning. (This may be useful in scripts.)
In low-level mode, if the device identifies as a Generic NMEA, use the
selected driver instead. This will be useful if you have a GPS device of
known type that is in NMEA mode and not responding to probes. (This
option was originally implemented for talking to SiRFStar I chips, which
don't respond to the normal SiRF ID probe.)
If no options are given, the program will display a message identifying
the GPS type of the selected device and exit.
Reset (-r) operations must stand alone; others can be combined. gpsctl
will execute multiple options in this order: mode change (-b or -n)
first, speed changes (-s) second, cycle rate (-c) third and control
strings (-x) last.
ENVIRONMENT VARIABLES
By setting the environment variable GPSD_SHM_KEY, you can control the key
value used to designate the shared-memory segment removed with the -R
option. This will be useful mainly when isolating test instances of gpsd
from production ones.
EXAMPLES
gpsctl /dev/ttyUSB0
Attempt to identify the device on USB serial device 0. Time out after
the default number of seconds. Adding the -f will force low-level
access and suppress the normal complaint when this tool can't find a
GPSD to work through.
gpsctl -f -n -s 9600 /dev/ttyUSB0
Use low-level operations (not going through a gpsd instance) to
switch a GPS to NMEA mode at 9600bps. The tool will identify the GPS
type itself.
gpsctl -x '\xb5\x62\x0a\x04\x00\x00\x0e\x34'
Send a request for UBX-MON-VER to a gpsd connected GNSS receiver.
BUGS
SiRF GPSes can only be identified by the success of an attempt to flip
them into SiRF binary mode. Thus, the process of probing one of these
running in NMEA will change its behavior.
Baud rate and mode changes work in direct mode but are not reliable in
client mode. This will be fixed in a future release.
RETURN VALUES
0
on success.
1
on failure
SEE ALSO
gpsd(8), gpsdctl(1), gps(1), ubxtool(1), zerk(1)
RESOURCES
Project web site: <https://gpsd.io/>
COPYING
This file is Copyright 2013 by the GPSD project
SPDX-License-Identifier: BSD-2-clause
AUTHOR
Eric S. Raymond
GPSD, Version 3.25 2023-01-10 gpsctl(1)
gpsd 3.25 - Generated Thu Feb 2 15:10:22 CST 2023