To make our series complete, here are the instructions how to setup ExtGPS for Linux applications, using Bluetooth serial port.

Unlike the other howtos, this one is command line based. Probably suits better for Linux enthusiasts :-)

Make sure ExtGPS is up and running and your phone is discoverable. In the following dumps, aa:bb:cc:dd:ee:ff should be your phone's Bluetooth MAC address.

Perform a scan for "Serial Port" services:

ubuntu@ubuntu:~$ sdptool search SP
Inquiring ...

Searching for SP on aa:bb:cc:dd:ee:ff ...
Service Name: Symarctic ExtGPS
Service Description: Share phone's built-in GPS ...
Service Provider: Symarctic Solutions
Service RecHandle: 0x10016
Service Class ID List:
  "Serial Port" (0x1101)
Protocol Descriptor List:
  "L2CAP" (0x0100)
  "RFCOMM" (0x0003)
    Channel: 5
Language Base Attr List:
  code_ISO639: 0x656e
  encoding:    0x6a
  base_offset: 0x100

(... continues with other services...)

Create /dev/rfcommX device for ExtGPS, by "rfcomm bind" command. Note the parameters, "1" is the id for /dev/ entry, mac address and the last one is RFCOMM channel ID from service, in my case it's channel 5 (chanel no. 5 ?):

ubuntu@ubuntu:~$ sudo rfcomm bind 1 aa:bb:cc:dd:ee:ff 5

When application connects to /dev/rfcomm1, it's opened to ExtGPS. You can test the connection, e.g.:

ubuntu@ubuntu:~$ cat /dev/rfcomm1

After this, the connection icon on ExtGPS should be green and device name shown next to it. If the satellite icon is also green (meaning a fix), you should now see raw GPS NMEA data on your terminal. Issuing Ctrl-C should break the connection, turning the connection icon back to red.