gps.rb

#!/usr/bin/env ruby

require 'socket'

Socket.const_set :AF_BLUETOOTH, 31
Socket.const_set :BTPROTO_RFCOMM, 3

module Bluetooth
  refine Socket.singleton_class do
    def bt_sockaddr bdaddr, channel
      [Socket::AF_BLUETOOTH, 0, *bdaddr.scan(/\h\h/).reverse_each.map(&:hex), channel, 0].pack('C*')
    end
  end
end

class GPS
  using Bluetooth
  
  def initialize bdaddr, channel
    @bdaddr  = bdaddr
    @channel = channel
    @file    = "coordinates.gps"
    @parser  = GPSParser.new
  end
  
  def run
    @socket = Socket.new Socket::AF_BLUETOOTH, :SOCK_STREAM, Socket::BTPROTO_RFCOMM
    @socket.connect Socket.bt_sockaddr @bdaddr, @channel
    
    loop do
      gps_data = @socket.gets 
      puts gps_data
      if gps_data.start_with?("$GPGGA") && gps_data.size == 62
        parsed_data = @parser.parse_gps_data(gps_data).join(',')<<$/
        File.write(@file, parsed_data, mode: 'a') # create KML file with coords ???
      end
    end
  ensure
    @socket.close if @socket
  end
end

class GPSParser
  def parse_gps_data gps_data
    lat, lon = gps_data = gps_data.split(',').values_at(2..5).each_slice(2).to_a
    lat_degrees = parse_latitude(*lat)
    lon_degrees = parse_longitude(*lon)
    [lat_degrees, lon_degrees]
  end
  
  def parse_latitude lat, heading
    degrees = lat[0,2].to_f + (lat[2,lat.size].to_f / 60.0)
    heading == 'N' ? degrees : -degrees
  end
  
  def parse_longitude lon, heading
    degrees = lon[0,3].to_f + (lon[3,lon.size].to_f / 60.0)
    heading == 'E' ? degrees : -degrees
  end
end


bdaddr  = "60:BE:B5:FE:1D:61"
channel = 5 

gps = GPS.new bdaddr, channel
gps.run