Bluetooth for ARM embedded linux

Question

I'm struggling now for a few days to setup bluetooth services on an ARM embedded device running Linux. I'm using a bluetooth dongle connected via USB.

Let's start with the beginning. I had to compile myself all the required packages, and that means expat, dbus, zlib, libffi, glib, bluez-3.36-libs and bluez-3.36-utils (yeah 3.36, I know they're old but so is my cross-compiler), libopenobex-1.3, obexd-0.3, obexftp. Then I put the binaries and libs on the device. Also, bluetooth is enabled in kernel.

I'm able to activate the bluetooth using hciconfig hci0 up command, I can perform scan using hcitool scan, I can even ping with l2ping previously discovered devices.

What I want is to be able to transfer files between that ARM device and another bluetooth device using ftp protocol and here my problems begin.

1. Are these the only tools that I need?

2. After putting everything on the device, I turn on bluetooth using hciconfig hci0 up, then I start dbus daemon using dbus-launch and after these I try to start obexd. When I run dbus-launch, it prints the values for DBUS_SESSION_BUS_ADDRESS and some pid and next when I try to start obexd it asks me to set the DBUS_SESSION_BUS_ADDRESS. Is this normal because I read that you have to set this only for test purposes? What is the default (real) dbus session bus address? How should I properly configure dbus?

3. I tend to think that the problem is in the pairing process, when the two bluetooth devices are trying to authenticate. How can I do this from command line as this is all that I have (no GUI)?

4. Could you please present me the detailed step to follow in order to achieve my goal. I tried to learn more about them from the Internet and also I tried to find these steps online but I could not find what I need.

5. Could you please explain me the difference between obexd, obexd-client, obexd-server, obex-data-server, obexftp? Are they meant to be used together or they offer the same functionalities? I could not clarify this from their man pages.

I know this is a really long post with a lot of questions, but I don't have experience with bluetooth and I'm under time pressure to solve this. Any help would be kindly appreciated.

Answer 1

Many questions you raised, but will try to answer them :

1. Thatz pretty much everything you will need.

2. Why are you starting session bus ? Will not starting system bus help and hcid uses system bus( as far as i know ). You need to execute the cross-compiled obexd ( or any other utility) with correct parameters.

3. you can use simple-agent ( it is in tools dir in 3.36 release if i am not wrong ). In a non-gui mode ( simple-agent --default [ follower by your pincode ] ) will work.

4. Basically you will need to find a device ( do scan ), authenticate ( pair ) and then proceed with file transfer which will involve obex level request / response ( to put in simple words).

5. As much i know, initially obexftp / obex-push were the only standalone utilities that worked on top of openobex for file transfer. Obex-data-serer was developed as part of GSOC competition, which got included in major distros. obexd is the slimmer version of obex-data-server specifically designed for embedded usage and is closely integrated with hcid ( and bluetoothd later). Please use only one of the utilities and not all at same time.