nmea(n) NMEA protocol implementation nmea(n) 







nmea - Process NMEA data








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?












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.









  
::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"
}
    

  










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.








gps, nmea








Networking








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








  

    1.0.0
    nmea