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#!/usr/bin/env ruby -w
# encoding: UTF-8
#
# = EPO_Downloader.rb -- PostRunner - Manage the data from your Garmin sport devices.
#
# Copyright (c) 2015 by Chris Schlaeger <cs@taskjuggler.org>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of version 2 of the GNU General Public License as
# published by the Free Software Foundation.
#
require 'uri'
require 'net/http'
module PostRunner
# This class can download the current set of ephemeris data for GPS
# satellites and store them in the EPO.BIN file format. Some Garmin devices
# pick up this file under GARMIN/GARMIN/REMOTESW/EPO.BIN.
class EPO_Downloader
@@URI = URI('http://omt.garmin.com/Rce/ProtobufApi/EphemerisService/GetEphemerisData')
# This is the payload of the POST request. It was taken from
# http://www.kluenter.de/garmin-ephemeris-files-and-linux/. It may contain
# a product ID or serial number.
@@POST_DATA = "\n-\n\aexpress\u0012\u0005de_DE\u001A\aWindows\"\u0012601 Service Pack 1\u0012\n\b\x8C\xB4\x93\xB8\u000E\u0012\u0000\u0018\u0000\u0018\u001C\"\u0000"
@@HEADER = {
'Garmin-Client-Name' => 'CoreService',
'Content-Type' => 'application/octet-stream',
'Content-Length' => '63'
}
# Create an EPO_Downloader object.
def initialize
@http = Net::HTTP.new(@@URI.host, @@URI.port)
@request = Net::HTTP::Post.new(@@URI.path, initheader = @@HEADER)
@request.body = @@POST_DATA
end
# Download the current ephemeris data from the Garmin server and write it
# into the specified output file.
# @param output_file [String] The name of the output file. Usually this is
# 'EPO.BIN'.
def download(output_file)
return false unless (epo = get_epo_from_server)
return false unless (epo = fix(epo))
write_file(output_file, epo)
Log.info "GPS caching data has been downloaded from Garmin site."
true
end
private
def get_epo_from_server
res = @http.request(@request)
if res.code.to_i != 200
Log.error "GPS data download failed: #{res}"
return nil
end
res.body
end
# The downloaded data contains ephemeris data for 6 hour windows for 7
# days. Each window set is 2307 bytes long, but the first 3 bytes must
# be removed for the FR620 to understand it.
# https://forums.garmin.com/showthread.php?79555-when-will-garmin-express-mac-be-able-to-sync-GPS-EPO-bin-file-on-fenix-2&p=277398#post277398
def fix(epo)
unless epo.length == 28 * 2307
Log.error "GPS data has unexpected length of #{epo.length} bytes"
return nil
end
epo_fixed = ''
0.upto(27) do |i|
offset = i * 2307
epo_fixed += epo[offset + 3, 2304]
end
epo_fixed
end
def write_file(output_file, data)
begin
File.write(output_file, data)
rescue IOError
Log.fatal "Cannot write EPO file '#{output_file}': #{$!}"
end
end
end
end
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