Sniffing a Bosch laser tape 2

[Dainius G]

Hi.

I`m trying to figure out a way I can control a Bosch GLM120C laser measure device using a micro controller.

I`m a stage where I can activate  the laser(1st command) and take a measurement(2nd command) using NRF connect app on my phone.

Service UUID: 2A6C0D0-0451-4000-B000-FB3210111989

Command I`m writing "c05601001e"  first time it activates the laser and 2nd time it takes a measurement. 

While the app from Bosch does get the distance value. I can`t seem to figure out what packet  the data is being sent back in, I`m using Wireshark and BLE sniffer(52 dongle).

https://www.dropbox.com/s/z97dv8qdbm8emja/514mm%282%29.pcapng?dl=0

Any input would be much appreciated. 

Thanks Guys.

[Dainius G]

Hi SparkyBert thanks for your help.
Yes I have figured out how data is sent back to the "master" device as a float value.

I have decompiled "Bosch MeasureON" android apk file using "JADX"https://github.com/skylot/jadx

https://www.dropbox.com/s/3xcvlzzflls3eky/Crc.PNG?dl=0
https://www.dropbox.com/s/x2gimzjl9at4388/MtBLE.PNG?dl=0
https://www.dropbox.com/s/x0x5j41wt9qxgzp/MtFrame.PNG?dl=0
https://www.dropbox.com/s/loe53yrf6579fnr/MtProtocol.PNG?dl=0

And there is tons of info on Bosch GLM100C measure tape connection protocols, crc calculation, both classic and BLE......

[Sparkybert]

Hi Dainius G,

thank you for the information. JADX sounds interesting. I might have a look at it in the future.

I tried to suppress advertising packets of the GLM120C using drastic measures, but to no success.
Good luck with your micro controller application.

[run_ar]

Maybe you have enabled the "TrackMyTools" feature or something, which in case it would make sense to advertise while in "off" mode?

[Sparkybert]

Hi run_ar,

thank you very much for your hint. You were absolutely right.
I checked my original manual again, which mentions TrackMyTools (TMT) briefly. The manual only says that you can turn it on or off in the settings and that there is a dedicated app for it. That's pretty much it.

Anyway, I turned TMT off in the device settings and tested again and it actually stopped advertising when the device is turned off.

Thanks again.