Mares Quad with BLE Interface
Dirk Hohndel
dirk at hohndel.org
Tue Apr 10 13:10:23 PDT 2018
> On Apr 10, 2018, at 9:44 AM, Linus Torvalds <torvalds at linux-foundation.org> wrote:
>
> On Tue, Apr 10, 2018 at 9:26 AM, Dirk Hohndel <dirk at hohndel.org> wrote:
>>
>> What's our best bet to create a process to do this?
>> Ask people to send their dive computers to Linus? Tempting, but maybe
>> not as scalable as one might hope.
>
> Yeah. Especially since I wouldn't be very motivated by most dive
> computers. I've not been all that excited about the Mares ones I've
> seen: the Icon HD is ok, but I had issues with the screen.
This was intended as a joke...
>> Instructions how to create a BLE trace (I guess on Android?)?
>
> Yeah, but we know how easy _that_ can be, particularly since Android 8
> (or something) apparently broke the documented ways by hiding the
> trace. So you can get a trace, but _accessing_ that trace is
> apparently impossible now.
>
> (Or maybe google fixed it? I haven't tried).
>
> But yes, at a minimum we'd need a BLE trace of a successful download,
> and the BLE GATT descriptor listing (getting *that* is a pain too, the
> best approach seems to be "use Nordic's nRF connect, and then expand
> all the descriptors, and take screen shots", which isn't very
> user-friendly either.
>
> So both of those are somewhat painful for your average user that
> doesn't really know anything about BLE.
>
> We were very lucky with Berthold and the Aladin Sport. He did his own
> fake GATT server and tricked the LogTrak mobile app to talk to his
> desktop and got some traces that way. With *that* kind of expertise
> on the user side, supporting the result was pretty easy. He did all of
> the heavy lifting himself.
The question is, can any of this be well documented or even automated?
Berthold, any suggestions?
I remember the Android process being reasonably painful - even without
Google hiding the output file from you.
Some googling seems to come up with quite a few posts on how to do this:
https://learn.adafruit.com/reverse-engineering-a-bluetooth-low-energy-light-bulb/sniff-protocol
It seems that using this device really helps
https://www.nordicsemi.com/eng/Products/Bluetooth-low-energy/nRF-Sniffer
https://www.semiconductorstore.com/cart/pc/viewPrd.asp?idproduct=50443
But that's $45 or so - not something that we can ask the casual diver to buy...
Hmmm... running out of easy ideas
/D
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