path: root/INSTALL

= GPSD Installation Instructions =

Here are the steps for installing GPSD and verifying its performance.
They assume you have GPSD available as an installable binary package, 

Instructions for building GPSD from source (including cross-building)
are in the file "build.txt" in the source distribution.

Most of these installation instructions are generic to Linux (inc 
There are some special notes on installation for OS X and the Raspberry Pi
near the end of this file.

== Check that your GPS is live and you can get data from it ==

Start by making sure you can get data from your GPS, otherwise the later
steps will be very frustrating.  In this command

      stty -F /dev/ttyXXX ispeed 4800 && cat </dev/ttyXXX

replace ttyXXX with the filename of the port.  This will probably be
either /dev/ttyUSB0 or /dev/ttyS0. If you are on a *BSD Unix or MacOS X,
replace -F with -f.

When you run this command, you should see text lines beginning with $
come to stdout (possibly after a short initial burst of binary
garbage).  If you don't see this, you may have OS-level problems with
your serial support, but more likely have the wrong device.  Look
again.

If you have trouble with the preceding step, check your cabling
first.  Verify that the device is connected and that its power LED
(if it has one) is lit.

If you seem to have some sort of serial-device problem, check that
your kernel properly supports the device you are using.  For GPSes
using an RS-232 port (which is no longer common) you will need
serial-port support compiled into your kernel.  Various USB-to-serial
adapter chips found in GPSes require specific drivers.

Under a stock Linux kernel these will all be loaded on demand when
the USB system sees the appropriate vendor/product ID combinations.
See build.txt for instructions relating to custom kernels.

== Check that your system configuration will allow GPSD to work ==

Ensure that device permissions will enable gpsd to read from and write
to GPS devices even after it drops root privileges.  If you are
running Fedora Core, Ubuntu, or stock Debian you can skip this step,
as the stock configuration has the right properties.

gpsd requires two things: (1) that GPS devices have group read and
write enabled, and (2) all of them are have the same group ID as a
prototypical device, typically /dev/ttyS0 under Linux or /dev/tty00
under *BSD. It does not actually matter what the owning group is, as
gpsd will look this up on startup.  Alternatively, (3), you can set a
fallback group with the gpsd-group option in case the prototype is not
found: this should be the group that has write access to serial
devices.  On Debian and derivatives including Ubuntu this is "dialout";
on Gentoo/Fedora/openSuse it is "uucp".

Before dropping privileges, gpsd will ensure that it has access to
devices given to it on the command line by forcing their group read
and write permissions on.

On a Linux with udev, check the files in /etc/udev/permissions.d to
ensure that /dev/tty* devices are all created with the same group 
and with 0660 permissions.

When gpsd drops privileges, its default is to set uid to 'nobody' and
group to the owning group of the prototype device (the configure
option gpsd-user=foo will cause gpsd to change to 'foo'
instead).

If your system has the Linux hotplug facility installed you can skip
the permission-setting part; the hotplug scripts will force the
permissions for you.  You still have to make sure all the tty devices
are in the same group.

== Check your installation prerequisites ==

A minimum build of GPSD can run pretty close to the metal; all it
absolutely needs is the C runtime support. The test clients and
various additional features have additional prerequisites:

|==========================================================================
|pthreads library       | support for PPS timekeeping on serial GPSes
|DBUS                   | gpsd will issue DBUS notifications 
|ncurses                | a test client and the GPS monitor depend on this
|libtinfo5              | shared low-level terminfo library (see below)
|libusb-1.0.x or later  | better USB device discovery
|Qt + qmake             | libQgpsmm depends on this
|python2.x, x >=6       | required for various clients and utilities
|pgtk-2/cairo bindings  | the main test client, xgps, needs this
|==========================================================================

Some ncurses packages contain the terminfo library; some break it out
separately as libtinfo5 or libtinfo.

The Python code in GPSD is actually compatible back to Python 2.4 except that
you need either the json library module from 2.6 or the functionally
equivalent simplejson backport.

== Installing gpsd ==

=== Install your distributions package(s) ===

Up-to-date gpsd packages are generally available for Linux
distributions including Debian and derivatives (including Ubuntu and
Mint), Fedora and derivatives (including CentOS), openSUSE, PCLinuxOS,
Mageia, and Slackware.  In the embedded space, CeroWRT carries
GPSD. The GPSD package in the FreeBSD ports tree is also reliably up
to date.  Even if your distribution is not on this list, it is quite
likely GPSD has already been packaged for it.

Whatever distribution you are running, the name of the core GPSD
package containing the service daemon is almost certainly "gpsd".
However, many distributions break up GPSD into separate installable
packages for the core daemon and clients; you should search your
repository index for anything with gpsd as a prefix.

=== Install from source code ===

Directions for installing from source are in the file build.txt found
in the source distribution.

== How to test the software ==

1. Start gpsd.  You'll need to give it as an argument a path to 
a serial or USB port with a GPS attached to it.  Your test command
should look something like this:

       gpsd -D 5 -N -n /dev/ttyUSB0

2. Once gpsd is running, telnet to port 2947. You should see a
greeting line that's a JSON object describing GPSD's version.
Now plug in your GPS (or AIS receiver, or RTCM2 receiver).

3. Type '?WATCH={"enable":true,"json":true};' to start raw and
watcher modes.  You should see lines beginning with '{' that are
JSON objects representing reports from your GPS; these are reports
in GPSD protocol.

4. Start the xgps or cgps client.  Calling it with no arguments should
do the right thing.  You should see a display panel with
position/velocity-time information, and a satellite display.  The
displays won't look very interesting until the GPS acquires satellite
lock.

5. Have patience.  If you are cold-starting a new GPS, it may take
15-20 minutes after it gets a skyview for it to download an ephemeris
and begin delivering fixes.

6. A FAQ and troubleshooting instructions can be found at the GPSD 
project site.

== Once you have verified correct operation ==

1. If you installed from a .deb under Debian or a Debian-derived 
system, you may need to `dpkg-reconfigure -plow gpsd' to enable the
hotplug magic ("Start gpsd automatically").

2. Check out the list of supported hardware at the Hardware page on
the GPSD project's website. If your GPS isn't on the list, please send
us information to add a new line to the table.  Directions are
included on that page. We can also use updates of the latest version
number known to work with hardware already supported.

3. GPSD includes a PHP script that you can use to generate a PHP
status page for your GPS if you wish. (It may not be in the core
package.)  It will be installed in your HTTP document directory. The
first time it's invoked, it will generate a file called
'gpsd_config.inc' in that directory containing configuration
information; edit to taste.

For special instructions related to using GPSD for time service, see the
GPSD Time Service HOWTO in the distribution or on the web.

== Special Notes for OS X Installation ==

gpsd will build, install and run on OS X.  The easiest way to do so is
to first install the MacPorts package.  Follow their install procedure
at: http://www.macports.org/install.php

Then use their port command to install scons, and optionally git if you 
want to access the develpment source.

--------------------------------------------------------------
# port install scons
# port install git
--------------------------------------------------------------

While runnning gpsd, or scons check, you may run out of shared memory
segments.  If so, you will see this error message:

--------------------------------------------------------------
gpsd:ERROR: shmat failed: Too many open files
--------------------------------------------------------------

By default OS X allows a very small number of shared segments.  You
can check your allowed maximum number of shared segments, then increase
the maximum number, with these commands:

--------------------------------------------------------------
# sysctl kern.sysv.shmseg=8
kern.sysv.shmseg: 32 -> 8
#   sysctl -a  | fgrep shmseg
kern.sysv.shmseg: 8
# sysctl kern.sysv.shmseg=16
kern.sysv.shmseg: 8 -> 16
#   sysctl -a  | fgrep shmseg
kern.sysv.shmseg: 16
--------------------------------------------------------------

If you are using a USB based GPS you will likely need the Prolific
PL2303 driver.  You can find it here:
http://www.prolific.com.tw/US/ShowProduct.aspx?p_id=229&pcid=41

== Special Notes for Rasberry Pi Installation ==

gpsd will build, install and run on the Rasberry Pi (RasPi) using Debian
Wheezy.  Other distributions will likely work fine as well.  The gpsd
package in Debian Wheezy is known to be flakey, be sure to update to a
new version of gpsd from source.

Before compiling gpsd from source, you will need to update your system
as root:

--------------------------------------------------------------
# apt-get update
# apt-get dist-upgrade
# rpi-update
# reboot
--------------------------------------------------------------

Next, Wheezy requires a few tools for compiling and testing gpsd:

--------------------------------------------------------------
# apt-get install scons libncurses5-dev python-dev pps-tools
# apt-get install git-core
--------------------------------------------------------------

Git-core is only required to build from a git repository.  pps-tools is for
testing PPS inputs.  You need scons at 2.3.0 or higher to build.

If your scons is less than 2.3.0 you will need to get a newer scons
from wheezy-backport.  Partial instructions are detailed here:
http://backports.debian.org/Instructions/

Basically you need to add  this line to /etc/apt/sources.list:

--------------------------------------------------------------
deb http://http.debian.net/debian wheezy-backports main
--------------------------------------------------------------

Then do another update:

--------------------------------------------------------------
apt-get update
--------------------------------------------------------------

Which may lead you to this error if you lack a full set of debian keys:

--------------------------------------------------------------
W: GPG error: http://http.debian.net wheezy-backports Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8B48AD6246925553
--------------------------------------------------------------

Partial but detailed instructions to fix that are here:

--------------------------------------------------------------
https://wiki.debian.org/SecureApt
--------------------------------------------------------------

In short, get the missing key, import into apt, and do the update:

--------------------------------------------------------------
gpg  --recv-keys 8B48AD6246925553
gpg -a --export 46925553 |  apt-key add -
apt-get update
--------------------------------------------------------------

You can now install scons from the wheezy-backports repository:

--------------------------------------------------------------
apt-get -t wheezy-backports install scons
--------------------------------------------------------------

The rest of the installation is just as for any other source based
install, as noted in the file build.txt.

Any USB connected GPS that is known to work with gpsd will work fine on
the RasPi.  No special instructions apply.

A very popular option is to install the AdaFruit Ultimate GPS HAT.  With
this GPS you also get a good 1PPS signal.  This works as any other GPS
with gpsd, but there are two things to note.  The GPS takes over the
serial console: /dev/ttyAMA0.  The PPS signal will be on GPIO Pin #4.

Only two specific changes need to be made to make the HAT work.  First
in the file /boot/cmdline.txt, remove this part "console=ttyAMA0,115200
kgdboc=ttyAMA0,115200)".  That frees the serial port from console use so
the GPS can use it.

Second you need to tell the boot process to load the pps_gpio module
and attach /dev/pps0 to GPIO ping 4.  Do that by adding this line
to the bottom of /boot/config.txt: dtoverlay=pps-gpio,gpiopin=4

Reboot and proceed as for any other operating system to use gpsd.

Warning, the pps_gpio driver in all linux kernels up to the current
3.19 only reports one edge.  Be sure to validate that your PPS signal
is not offset by the pulse width.

Detailed instructions are available from their web site:
https://learn.adafruit.com/adafruit-ultimate-gps-hat-for-raspberry-pi/

You will need to dig deeper to make the PPS work, here is a good reference:
http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html