Sending sensor values from the Bangle.js 2 to my Smartphone

[leonkansti]

Hello, Im new to this forum and this question might be a bit "nooby". Basically i consider using a Bangle.js 2 to track vital datas like HR. I want the data to be sent to my smartphone where i can display it in a App that i am going to develop. Before i order things, i would like to ask if my plan is realistic.

Is it possible to send vital data like HR to my smartphone via BLE? (I couldn't find a example in here)
The other question i have is about the memory, because it says there is 8mb of flash available. Does vital data and sensor data get safed locally on the watch so that i can sync it later on with my phone, or can i only send the current values (not sure how "much" sensor values can be stored with 8mb)?

Thank you so much i appretiate a lot if someone could help me out

[gfwilliams]

Hi! Yes, sending data from Bangle.js to the PC is realistic and very easy to do. There's an example of sending some data to a Web Bluetooth webpage at https://www.espruino.com/Bangle.js+Data+Streaming that you can try - the code on Bangle.js will be the same, you just have to write your app to read the data from Bluetooth LE.

Does vital data and sensor data get safed locally on the watch so that i can sync it later on with my phone,

Bangle.js automatically stores health data every 10 minutes (max/min heartrate, altitude, temperature, battery) if you have the Health app installed.

You can also save much more detailed data up to every second using the Recorder app and you can then download this as CSV/GPX/KML files afterwards.

... but we don't for example store raw accelerometer or heartrate sensor data with built-in apps. But nothing would stop you doing that if you wanted.

not sure how "much" sensor values can be stored with 8mb

• For health data, it's something like 100 years - so enough that you don't have to worry.
• For recorder data, each record is maybe 80 bytes, so in 8MB you get around 100,000 records. If you were recording once a second it'd last you about a day.

But if you record your own data, it really depends on how efficiently you store it and how often

[RKBoss6]

Just a question, do you have an iOS or android device? I'm pretty sure Gadgetbridge on android can support this, with maybe a few customizations. iOS is more restrictive, and building an app really is the only way to send data over...

[leonkansti]

Hello, I plan on using both platforms which is why I want to set up my own app. I heard of Gadgetbridge I think my app should do something like Gadgetbridge. I was already able to transfer live data from my Bangle to my Smartphone, now I will work on storing data locally on the Bangle to synchronise later with the smartphone.

[leonkansti]

Therefore I saw the App „Recorder“ in the Apploader as gfwilliams suggested. However id like to wright my own script. I am facing some challenges like:

• how to let a recorder run in the background all the time (where to store the code on the Bangle to make it run in the background)?
• How to make my recorder limit files saved to something like 4mb. After that I’d like to replace old data with newer data
• Also as a minor challenge, how to store data (I start with steps, HR, and Temperature) in the most efficient way and sent it later via Bluetooth
• After synchronisation via BLE with my smartphone I can delete the data on the watch to get space for new data

That’s more like a brainstorm for myself, I will try to work out those things by myself. So far I enjoy working with the bangle! I still appreciate input or Tipps:)

[RKBoss6]

Nice! I was planning on making an iOS app that would allow iOS shortcuts to trigger when the bangle advertises something, allowing functions like find my phone, etc. I would love to see this app in the future, and potentially contribute to it as well!

[gfwilliams]

To allow stuff to run in the background you need what we call "boot code" - you put a file in myapp.boot.js and that code will then run before any other app, so you can set things up like recording. I think StorageFile has a way to check how bit it is too? Or you can check require("Storage").getStats() to see how much is free - but that can take a while so I'd only do it once a minute or less.