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 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>