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 dispatched 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)
