App Development

Chat about Hammerhead's Karoo in general.
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Posts: 5
Joined: Sat Oct 03, 2020 10:46 pm

App Development

Post by brennancarley »

Has anyone done any application development specifically for the Karoo?

I know that Hammerhead don't provide an SDK, but I am curious to know:

- Are there any APIs that can be used (e.g. to hook into the menu, integrate into the status bar, or create new data fields that can be viewed in standard profiles)? My guess is not, at least not that Hammerhead has exposed outside of their own development team, but...

- Does anyone have any sample code for a Karoo app? I imagine I can start with sample code for a generic Android device, but it would be nice to be able to start off with something that is Karoo-specific.

I want to build an app to consume data from the Dexcom CGM (Continuous Glucose Monitor) so I can monitor my blood glucose while I ride, just as I can monitor my heart rate, power, speed, cadence, or any other metric. Dexcom provides an API, so I can get the blood glucose data in realtime, I just need to display it on my Karoo, and ideally would like to do that as a data field that is displayed alongside other data fields.

I haven't developed software in years, but once upon a time I did operating system development, i.e. right in the guts of the O/S, including assembler language and C programming, so I assume I should be able to shake some dust off my skills and build an app. I'm just looking for some examples to use as a starting point.

A company called SuperSapiens ( is doing something similar, but with the Abbott Libre Sense Glucose Sport Biosensor, and they don't have any integration with bike computers... i.e. It is all on your phone.
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Joined: Fri Oct 18, 2019 1:11 pm

Re: App Development

Post by the5krunner »

Hi Brennan

I have an interest in your topic.

Please update me if you get anywhere with a product (I could help publicise it, if it's good)
Posts: 58
Joined: Mon Dec 09, 2019 5:11 pm

Re: App Development

Post by bikebikebike »

As I become more involved in the head unit training process,
I like the way that the Karoo lets me play with trying to identify what data is useful
and at what tempo.
Some I like in real time eg speed cadence
Some I can wait until I get home.
What would you see as useful periodicity in Glucose Monitoring?
Given impact of delay in insulin release , action , gluconeogensis and the pharmacodynamics and kinetics of insulins and other meds and rates of consumption, is real time monitoring more useful than say q 5 min? What would you change?
I don't think you are going to be able to use the bike as a glucose clamp, but there is

That said an APK , store or even just a limited list of apps they could support is one of the hovering potentials
that has dogged the competitive position of the Karoo since before its introduction.
Creation of these would be just a small part of the cost to them for opening this up.
Support would get capsized fast and group support is a strong alternative , that has not really been built up.
HH Support has been able to work with a few folks like John,
but could get overwhelmed in a heartbeat and become a flame magnet, with more toxicity than benefit to the company.
Look at the flaming on FB when folks get befuddled by quirks and stumbles.

This board is ideally situated for the support because the topology of the Zendesk and FB
don't lend themselves to much searchable, long form, deeper interaction.
They are designed for posting selfies, ride videos and short chat, not development and debugging.
Indeed most of the HH Community posts go to "File a ticket", then disappear, if the HH guys ( great, all of them) pop in.

Perhaps we could see if the HH guys that know the device well could form more than one ATG to look at the issues that are relevant , but are not on the main road of their roadmap.
Like Sideloading and exploring apps that work and new apps to beta test
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Joined: Sat Oct 03, 2020 10:46 pm

Re: App Development

Post by brennancarley »

Thanks for the reply.

I am aiming for 5 minute intervals. That is the frequency that the Dexcom app reports blood glucose, which it makes available via a RESTful API. I don't need more frequent than that, and the data would likely be more noisy if sampled more frequently anyway. And in any case, the Dexcom app only samples every 5 minutes. So 5 minute intervals are easily available, and seeing my blood glucose that frequently is helpful (and being able to observe the trend, i.e. If it is 80mg/dl and going down that is very different than 80mg/dl and rising). I am diabetic, so it helps me anticipate if I need to eat/drink carbs, or worst case, turn around and head home. For someone who is just using blood glucose monitoring for analysis purposes, waiting until you get home is fine.

For now I have solved this problem by sideloading Firefox and running Sugarmate ( in the browser. Sugarmate provides a graph in 5 minute intervals, pulling from the Dexcom site, which gets it's data from the Dexcom app running on my phone, which gets the glucose measurements from a sensor via bluetooth. It works, so I'm not in a big hurry to write an app right now, but if I can build an app that hooks into the Karoo as seamlessly as Heartrate, cadence, etc, that would make it a little nicer!

I understand the challenge in opening up, offering an SDK, and then supporting that. But I do hope they do it, and it would be a huge differentiator.
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