Help!!! Question of Sense2 and Companions API

[KP.CHAN]

I would like to develop an app to real-time monitoring heart rate, breathing rate and skin temperature. Before start develop I wish to understand some technical questions. Wish someone can answer my questions, Thank You

1.What is the storage of fitbit sense 2? How many gigabyte is usable?

2.What is the delay time from device to app developed by companions api(or Fitbit mobile app)?

3.What is the package of data  receive from device include ? For the heartrate and breathing rate can sync everytime when detected or it will send with package (example sync data after 5 times result detected and sync 5 of the result in single sync)?

4.What is the frequency of the device to detect heartrate and breathing rate?

[t.parker]

Sorry but Sense 2 (and Versa 4) don't support thirdparty development so you won't do anything with this watch. You may want to use original Sense or Versa 3 in that matter which have such capability. Ideally, ask in this forum (SDK and development related).

[Guy_]

Hi @KP.CHAN - as @t.parker has pointed out it is not possible to develop for the Sense 2 and Versa 4.

Recently the Fitbit Studio development platform was removed making it much harder to develop for any watch, even for some of the experienced people.

That said, the real time Heart rate is available directly to a clock or app. This is provided by the watch each time it polls which may be more than once per second.

The available space if harder to estimate because it depends on how a watch is used, what other apps [if they were permitted] have gobbled up space.

Also the time between companion communicating with the watch is dependent on how well the watch is syncing in addition to any processing latency.

Neither breathing rate or skin temperature is available directly in real time, a daily value may be obtained using WEB API.

I have move this topic to SDK forum for consistency.

[KP.CHAN]

Is that means Sense 2 cannot stream real time the heartrate, breathing rate and skin temperature to my own mobile app?

[Guy_]

@KP.CHAN - as explained, it definitely can't, nor  more importantly can any Fitbit.

However if your watch is syncing well you will see current heart rate in the Fitbit app, albeit with a slight delay which is probably not significant.

[KP.CHAN]

If pass through the Fitbit mobile app, is that possible to stream the real-time data to my own app?

[Guy_]

@KP.CHAN  - may be a screen scraper app could get that information, such as possibly Macrodroid, but it is unlikely to give you real time data, unless there are no interferences, such as screen timeout or other activities, and it may exhaust your phone battery, and possibly watch, quite quickly.

You may be better off with a web app but again it is unlikely to be reliably real time.

[KP.CHAN]

Is that means I still can stream data from Fitbit Sense 2 but unlikely to give me the real-time data? Or I need change another watch?

[Guy_]

@KP.CHAN - as mentioned earlier nothing can be done using a Sense 2 or Versa 4.

[KP.CHAN]

Is other model allow to stream real time data to my own mobile app even need pass through fitbit mobile app?

[t.parker]

@KP.CHAN somebody is already trying to do something like that (streaming HR with Sense and Versa 3):

https://www.echoheartrate.app/fitbit

So probably it is possible but haven't seen it working (and website I linked says the solution is being beta-tested).

[Gondwana]

It will be possible to stream heart rate from Sense 2 and Versa 4 clockfaces when the SDK for those watches is released. Arrangements for non-clockface apps haven't been announced yet.

Heart rate can be streamed from earlier Versas and Sense now.

The only data that can be streamed is sensor data available through the Device API: see here.

It may be possible to get other data from the Web API, but that is only updated whenever the watch syncs.

[KP.CHAN]

is that real time streaming possible for Fitbit watch? I saw u have mentioned API rate limit is

150 times per hour before, that means only can sync every 24 sec of the data per hour. 

[Gondwana]

Rate limit only applies to Web API. You can't stream from the Web API because it isn't updated in real time.

[KP.CHAN]

Any limit of rate or size for device API, companions API and fetch()? 

To stream the real time data, do I need to develop Fitbit watch app and companions app ?

Can I directly use fetch() stream the data from fibit mobile app?

[Gondwana]

No rate or size limitations have been documented. I've managed to stream accelerometer data at 60Hz.

Yes, you need a watch clockface/app and companion app.

You can use fetch() in your companion app, which runs within the Fitbit mobile app, to send data directly to your own app or website. The app or website must function as a web server. In most cases, you'll need a non-self-signed SSL certificate on your server.

WebSockets are somewhat better for streaming because they keep a connection open and have lower overheads. However, handling WebSockets in your server can be harder.