telent · April 26, 2012 15:35 · Apr 26, 2012
diff --git a/polar.rb b/polar.rb
@@ -0,0 +1,65 @@
+require 'pp'
+require 'socket'
+
+module BluetoothPolarHrm
+  AF_BLUETOOTH=31               # these are correct for the Linux Bluez stack
+  BTPROTO_RFCOMM=3
+  class << self
+    def connect_bt address_str,channel=1
+    bytes=address_str.split(/:/).map {|x| x.to_i(16) }
+    s=Socket.new(AF_BLUETOOTH, :STREAM, BTPROTO_RFCOMM)
+    sockaddr=[AF_BLUETOOTH,0, *bytes.reverse, channel,0 ].pack("C*")
+    s.connect(sockaddr)
+    s
+  end
+
+  def decode bytes
+    # http://code.google.com/p/mytracks/source/browse/MyTracks/src/com/google/android/apps/mytracks/services/sensors/PolarMessageParser.java
+    start=bytes.index(0xfe.chr)
+    unless start then
+      warn "bad message #{bytes.inspect}"
+      return [nil,bytes]
+    end
+    start.zero? or bytes=bytes.slice(start..-1)
+    if (bytes.length < 2) || (bytes[1].ord > bytes.length)
+      return [nil,bytes]
+    end
+    ret={
+      len: bytes[1].ord,
+      chk: bytes[2].ord,
+      seq: bytes[3].ord,
+      status: bytes[4].ord,
+      hr: bytes[5].ord,
+    rr: [(bytes[6].ord << 8) | bytes[7].ord]
+    }
+    if ret[:chk]+ret[:len] != 255 then
+      warn "bad message #{bytes.inspect}"
+      return [nil,bytes]
+    end
+
+    [ret,bytes.slice(ret[:len]..-1)]
+  end
+
+  def connect(address)
+    Enumerator.new do |y|
+      pin=connect_bt(address)
+      buf=''
+      while(true) do
+        buf+=pin.recv(80)
+        data,buf=decode(buf)
+        if data 
+          row=data.merge({time: Time.now})
+          y << row
+        end
+      end
+    end
+  end
+  end
+end
+
+# ARGV[0] should be a bluetooth address (e.g. "00:22:D0:01:ED:3B").  You can find this with
+# "hcitool scan" or on probably a million  other ways
+
+BluetoothPolarHrm.connect(ARGV[0]).each do |d|
+  warn d
+end