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?
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 Trackers [
http://core.tcl.tk/tcllib/reportlist]. 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>