Ruby NMEA parser
C++ Ruby C
Switch branches/tags
Nothing to show
Clone or download
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Permalink
Failed to load latest commit information.
ext Left unimplemented zda and rmb Nov 3, 2007
lib Added nmea.rb Apr 11, 2007
parser Left unimplemented zda and rmb Nov 3, 2007
serialport Added serialport Nov 29, 2007
spec Left unimplemented zda and rmb Nov 3, 2007
test Added serialport Nov 29, 2007
.gitignore v0.4 Mar 19, 2009
README Added document with NMEA protocol May 9, 2007
Rakefile added gemspec Mar 19, 2009
init.rb Added documentation and changed NMEAError to ParseError Apr 10, 2007
nmea.gemspec added gemspec Mar 19, 2009
nmea.html
setup.rb Added documentation and changed NMEAError to ParseError Apr 10, 2007

README

Author::    Max Lapshin  (mailto:max@maxidoors.ru)
Copyright:: Copyright (c) 2007 Max Lapshin, Getalime
License::   Distributes under the same terms as Ruby

To use NMEA parser, you should somehow get data stream from Yor gps device.
For example, You can use ruby-serialport (which seems to be dead, but working).
The example on Mac with installed USB-Serial driver:

	require 'serialport'
	require 'nmea'
	@sp = SerialPort.open("/dev/tty.usbserial", 4800, 8, 1, SerialPort::NONE)
	@handler = NMEAHandler.new
	while(@sentence = @sp.gets) do
	  NMEA.scan(@sentence, @handler)
	end

NMEAHandler is a user class, that implements following interface:

	class NMEAHandler
	  def rmc(time, latitude, longitude, speed, course, magnetic_variation)
	    # read further about types of latitude and longitude
	  end
	  def gsv(flag, satellites)
	  end
	  def gsa(mode_state, mode, satellites, pdop, hdop, vdop)
	  end
	  def gga(time, latitude, longitude, gps_quality, active_satellite_count, gsa_hdop, altitude, geoidal_height, dgps_data_age, dgps_station_id)
	  end
	end

As you can see, the following NMEA sentences are supported currently: $GPRMC, $GPGSV, $GPGSA, $GPGGA.
If you need more, please contact me and provide me with several examples. I will add support for them.
NMEA::scan will not try to call unexistent method on your handler, thus you can implement only those
methods in your handler, you need to.

GSV handler has parameter flag. This flag can take one of the following values: <code>:start</code>, <code>:continue</code>
 and <code>:finish</code>. GSV messages appears in packs of several sentences, but NMEA::scan is stateless, 
thus your NMEAHandler should keep accumulate these messages.

It is important to mention, that NMEA::scan assumes, that You have classes GPS::Latitude and GPS::Longitude,
which initializer, takes two arguments: degrees and minutes. You can use this example:

	module GPS
	  AngleValue = Struct.new :degrees, :minutes

	  class AngleValue
	    def to_s
	      "%d %.4f%s" % [degrees.abs, minutes, symbol]
	    end
	  end

	  class Latitude < AngleValue
	    def symbol
	      degrees >= 0 ? "N" : "S"
	    end
	  end
	  class Longitude < AngleValue
	    def symbol
	      degrees >= 0 ? "E" : "W"
	    end
	  end
	end


Supported devices.

Ruby NMEA has full support of Globalsat BU-353 device (http://www.usglobalsat.com/item.asp?itemid=60&catid=17).

NMEA syntax is assumed to be as in document nmea.html, taken from http://www.werple.net.au/~gnb/gps/nmea.html