[Bluez-users] Best way to communicate with hidden devices

[Bluez-users] Best way to communicate with hidden devices

[Noel Paz]

I have a BT weight scale and I want to communicate to it. Problem is I 
think it is set to be un discoverable.  According to it's scant 
documentation it uses the BT serial protocol and a 128 bit encyrption 
and a PIN. - that it expects to start communication.  Supposedly, after 
it weighs something,  it tries to find an ACCESS point, see if the 
Access Point has the same PIN and if it does it transmits data packets 
which are very discrete

hcitool --scan and sdptool --browse cannot find it (yes I have made sure 
it can find other devices). I've turned hcidump too too make sure I can 
sniff it but to no avail

Honestly, I am new to BlueZ and have been devouring as much 
documentation as I can. My thoughts are setting up a PAN with an access 
point role using rfcomm. If anybody has worked on one way traffic 
bluetooth devices, let me know. I really have no way of knowing whether 
this weight scale  has a broken radio, although I can experiment with 
making my other devices undiscoverable with a PIN. Unfortunately their 
support is for Windoze only and require you to buy a container full of 
weight scales before their engineers will talk to you.

BTW there is a little sticker which seems to be the bdaddr.


Thanks

Noel


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Re: [Bluez-users] Best way to communicate with hidden devices

[Stephen Crane]

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On Wed, 2005-09-14 at 10:32 -0600, Noel Paz wrote:
> I have a BT weight scale and I want to communicate to it. Problem is I 
> think it is set to be un discoverable.  According to it's scant 
> documentation it uses the BT serial protocol and a 128 bit encyrption 
> and a PIN. - that it expects to start communication.  Supposedly, after 
> it weighs something,  it tries to find an ACCESS point, see if the 
> Access Point has the same PIN and if it does it transmits data packets 
> which are very discrete

This sounds like a very strange way of doing things. I'm sure they had
their reasons though.

> hcitool --scan and sdptool --browse cannot find it (yes I have made sure 
> it can find other devices). I've turned hcidump too too make sure I can 
> sniff it but to no avail

What did you browse for?

> Honestly, I am new to BlueZ and have been devouring as much 
> documentation as I can. My thoughts are setting up a PAN with an access 
> point role using rfcomm. If anybody has worked on one way traffic 
> bluetooth devices, let me know. I really have no way of knowing whether 
> this weight scale  has a broken radio, although I can experiment with 
> making my other devices undiscoverable with a PIN. Unfortunately their 
> support is for Windoze only and require you to buy a container full of 
> weight scales before their engineers will talk to you.

I did a bit of experimentation with a GPS device, documented here:
http://www.maths.tcd.ie/~jscrane/gps/

As described, this device provides a service to which you must connect
before it will spit out GPS data.

> BTW there is a little sticker which seems to be the bdaddr.

You could try running l2ping against that bdaddr: that should tell you
if its working.

Steve
-- 
Stephen Crane <jscrane@maths.tcd.ie>

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