Bluetooth transmission evesdropping

[danielharrelson]

I've got a G5 and I know that Loop is supposed to sniff broadcasts. Does it only do this if you use the official DexCom software on the phone? I use a G5 and use xDrip+ to put my numbers on the Dexcom servers, I have tried entering in my transmitter ID in the Loop app, but it always defaults back to data being pulled from the cloud. So, I'm curious how the eavesdropping works.

Per https://loopkit.github.io/loopdocs/requirements/cgm/ (unless it has changed)

In some instances, the Loop may fail to eavesdrop on the Bluetooth transmissions of the CGM systems. When that happens, the Loop can pull directly from Dexcom Servers to get the data (assuming you have entered your Share account information in the Loop settings). When Loop is operating in this mode, you will see a small cloud in the CGM reading in the Loop app. Operating in this mode requires a working internet or cell connection.

[Kdisimone]

Yes, still need the official dexcom software to be running on the iPhone if you want to pull BGs locally (vs pulling from Dexcom servers).

[Kryptonit3-zz]

Is this a iPhone limitation or a coding issue in Loop? How is xDrip+ on android able to achieve polling the G5 transmitter? I'd be interested in assisting in porting over this feature if it is feasible.

-- edit --

I mean, iosxdripreader is able to do this. I would prefer to have everything in one app, like getting Loop to get G5 data and input calibrations. Or is this not possible?

[danielharrelson]

You don't actually have to use "Dexcom Share", there are other methods. I've figured that much out, but the bluetooth eavesdropping is what I'm interested in. If you could do that @Kryptonit3 , you would be my hero.

[Kryptonit3-zz]

I would love to have everything localized. I know having a nightscout site up and running is beneficial in a number of ways and for seeing what is up with Loop if there are issues but I would like to see it all localized. I just hate that the data has to go back and forth.

[danielharrelson]

I've worked around the internet and gone "offline" by using an old iPhone 5 and leaving it unlocked. Loop will read from Apple HealthKit if there is no internet connection. iosxdripreader by Johan Degraeve will write the readings into health kit, and then loop will read them. The only problem is that you cannot lock your phone.

So, I carry around a dedicated device just for loop and cgm, but it works. There are also 3rd party "dexcom share" servers that will turn your nightscout data into the correct JSON format so Loop can use them and you can bypass Dexcom all together and keep your data private.

My needs/wants were to have a work phone running xdrip+, and then my personal phone running Loop and actively sniffing the G5 so I can replace batteries, and not be required to be tethered to the net.

Currently, for me to do this, I have to carry 3 phones (work phone, personal phone, and dedicated "diabetes phone"). It's a bit much, but it works.

[ps2]

It seems there might be confusion in this thread. Loop works great offline out of the box with G5 and G4 plus transmitter. Fetching from share is pirmarily to backfill, or help out in rare situations where local Bluetooth isn’t working for some reason.

[Kryptonit3-zz]

I guess my question is, is the Dexcom app required to use Loop? Can Loop be used standalone without assistance from Dexcom app or iosxdripreader to get data from G5 transmitter? If so, how does one enter calibration in Loop. Still new to iOS and Loop. Came from android and xDrip+ where all functionality for the loop was in one, and only one app.

Thanks!

[danielharrelson]

It only works great offline if you're using the official Dexcom application though, correct? Because with iosxdripreader it does not work offline unless the phone is unlocked. To clarify, I think of "bluetooth sniffing" as a promiscuous mode for the bluetooth protocol. The G5 is broadcasting, and the phone will capture the data even though it is not destined for that device. To my understanding, the application is not capable of performing in this manner.

…

On Sun, Nov 26, 2017 at 2:22 PM, Pete Schwamb ***@***.***> wrote: It seems there might be confusion in this thread. Loop works great offline out of the box with G5 and G4 plus transmitter. Fetching from share is pirmarily to backfill, or help out in rare situations where local Bluetooth isn’t working for some reason. — You are receiving this because you modified the open/close state. Reply to this email directly, view it on GitHub <#555 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AGcar-wj3atbiTNXUUXG_clC0frOllOXks5s6bpqgaJpZM4PBjkk> .

-- Daniel Harrelson GPG: http://www.t31.org/pub-gpg.txt

[Kryptonit3-zz]

Can the G5 transmitter not be accepted as a "trusted" device to allow the phone to be locked?

[ps2]

Yes, using Loop and allowing Dexcom to manage calibration, insertions, etc, is the primary use case we support with Loop.

Using other setups to get extended use of sensors or get access to raw data might be possible, but nobody has done the work to make it integrate nicely. Someone would need to implememt that functionality in a swift framework and develop uis in Loop for it.