nmea(n) 						   NMEA protocol implementation 						   nmea(n)

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NAME

       nmea - Process NMEA data

SYNOPSIS

       package require Tcl  8.4

       package require nmea  ?1.0.0?

       ::nmea::input sentence

       ::nmea::open_port port ?speed?

       ::nmea::close_port

       ::nmea::configure_port settings

       ::nmea::open_file file ?rate?

       ::nmea::close_file

       ::nmea::do_line

       ::nmea::rate

       ::nmea::log ?file?

       ::nmea::checksum data

       ::nmea::write sentence data

       ::nmea::event setence ?command?

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DESCRIPTION

       This  package  provides	a standard interface for writing software which recieves NMEA standard input data. It allows for reading data from
       COM ports, files, or programmatic input. It also supports the checksumming and logging of incoming data.   After  parsing,  input  is  dis-
       patched	to  user defined handler commands for processing.  To define a handler, see the event command. There are no GPS specific functions
       in this package. NMEA data consists of a sentence type, followed by a list of data.

COMMANDS

       ::nmea::input sentence
	      Processes and dispatches the supplied sentence. If sentence contains no commas it is treated as a Tcl list,  otherwise  it  must	be
	      standard comma delimited NMEA data, with an optional checksum and leading $.

	      nmea::input {$GPGSA,A,3,04,05,,09,12,,,24,,,,,2.5,1.3,2.1*39}
	      nmea::input [list GPGSA A 3 04 05  09 12 "" "" 24 "" "" ""  2.5 1.3 2.1]

       ::nmea::open_port port ?speed?
	      Open the specified COM port and read NMEA sentences when available. Port speed is set to 4800bps by default or to speed.

       ::nmea::close_port
	      Close the com port connection if one is open.

       ::nmea::configure_port settings
	      Changes the current port settings. settings has the same format as fconfigure -mode.

       ::nmea::open_file file ?rate?
	      Open file file and read NMEA sentences, one per line, at the rate specified by ?rate? in milliseconds.  The file format may omit the
	      leading $ and/or the checksum. If rate is <= 0 (the default) then lines will only be processed when a call to do_line is made.

       ::nmea::close_file
	      Close the open file if one exists.

       ::nmea::do_line
	      If there is a currently open file, this command will read and process a single line from it.  Returns the number of lines read.

       ::nmea::rate
	      Sets the rate at which lines are processed from the open file, in milliseconds. The rate remains consistant across files, there does
	      not need to be a file currently open to use this command.  Set to 0 to disable automatic line processing.

       ::nmea::log ?file?
	      Starts or stops input logging. If a file name is specified then all NMEA data recieved on the open port will be logged to the ?file?
	      in append mode. If file is an empty string then any logging will be stopped. If no file is specified then returns  a  boolean  value
	      indicating  if  logging is currently enabled. Data written to the port by write, data read from files, or input made using input, is
	      not logged.

       ::nmea::checksum data
	      Returns the checksum of the supplied data.

       ::nmea::write sentence data
	      If there is a currently open port, this command will write the specified sentence and data to the port in  proper  NMEA  checksummed
	      format.

       ::nmea::event setence ?command?
	      Registers a handler proc for a given NMEA sentence. There may be at most one handler per sentence, any existing handler is replaced.
	      If no command is specified, returns the name of the current handler for the given setence or an empty  string  if  none  exists.	In
	      addition	to  the  incoming  sentences there are 2 builtin types, EOF and DEFAULT. The handler for the DEFAULT setence is invoked if
	      there is not a specific handler for that sentence. The EOF handler is invoked when End Of File is reached on the open file or port.

	      The handler procedures, with the exception of the builtin types,must take exactly one argument, which is a list of the data  values.
	      The DEFAULT handler should have two arguments, the sentence type and the data values.  The EOF handler has no arguments.

	      nmea::event gpgsa parse_sat_detail
	      nmea::event default handle_unknown

	      proc parse_sat_detail {data} {
		  puts [lindex $data 1]
	      }

	      proc handle_unknown {name data} {
		  puts "unknown data type $name"
	      }

BUGS, IDEAS, FEEDBACK
       This  document, and the package it describes, will undoubtedly contain bugs and other problems.	Please report such in the category nmea of
       the Tcllib SF Trackers [http://sourceforge.net/tracker/?group_id=12883].  Please also report any ideas for enhancements you  may  have  for
       either package and/or documentation.

KEYWORDS

       gps, nmea

CATEGORY

       Networking

COPYRIGHT

       Copyright (c) 2006-2009, Aaron Faupell <afaupell@users.sourceforge.net>

nmea								       1.0.0								   nmea(n)