Doing simple HTTP requests through Companion app to receive CGM data

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Hotzenplotz_1337

• March 19, 2026 16:52

Hey there, I currently worked on an extension to display the CGM data of a Dexcom G7 as a data Field while navigating. It can show the current value, the difference to the previous value and a trending arrow for easier understanding of the trend. For now, I need to use my phone as Hotspot, connect the hammerhead to it to do the request to the Dexcom Share API around every 5 minutes. This in general works already fine but is there a way to use the Companion app for this simple requests without the need of an extra Hotspot, that would for sure drain the battery of the phone a lot faster? I am glad if someone more experienced can help me out here. Best regards Mark

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  timklge

  • March 19, 2026 18:19

  Hi, here is an example from my headwind extension's code: https://github.com/timklge/karoo-headwind/blob/master/app/src/main/kotlin/de/timklge/karooheadwind/weatherprovider/openmeteo/OpenMeteoWeatherProvider.kt

  There is also a ktor backend written by jonasfranz if you want to use a higher-level library: https://github.com/jonasfranz/ktor-client-karoo

  In all cases, the karoo will refuse to tunnel more than ~ 150 kB per request via the companion app, and bandwidth is very low (a few kb per sec at most); but it's great for the intended use of transmitting low-volume sensor data

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  Hotzenplotz_1337

  • March 19, 2026 21:17

  Thank you for your quick response, sounds both interesting, I will check that out this weekend 👌

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  Brennan Carley

  • April 07, 2026 01:29

  Hi, I am a few days away from going into beta with a pretty full function glucose monitoring app. It works with Dexcom and runs on the Karoo. It has a pretty robust set of data fields / visualizations, works in mg/dL or mmol/L, configurable scales for graphs, generates visual and audio messages when your glucose changes from one zone to another (zone ranges are configurable), honors light/dark mode, honors field alignment settings, etc, etc.. 

  It will be free with a "buy me a coffee" or similar option. (I use a Dexcom myself, which is the main reason I built it.)

  It is almost ready to go, I'm just finishing alpha testing, and the only functionality I need to add before I go into beta is language support... It is capable of all the Karoo supported languages, I am just waiting to do the translations and add the string resources until I get into beta, so I can get user feedback before doing the translations. 

   

  If you want to try it, hit me up at support@glucoroo.com

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  Hotzenplotz_1337

  • April 07, 2026 07:00

  Hey Brennan, I would be totally up to test your app or give you some feedback if you want to :). How do you handle doing requests? I currently still kept the way of doing so via the hotspot from my phone, as I did not have time to dig deeper into that topic.

  Have a good day

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