GATT service with Ruuvitag

[espruino-discuss]

Posted at 2017-04-13 by user75772

Hi there!

I'm trying to set up a GATT service on my ruuvitag. I have successfully installed the firmware following https://www.espruino.com/Ruuvitag and I can talk with the device and upload code 🎉

I've got the following code running:

var Ruuvitag = require("Ruuvitag");

NRF.setServices({
  0xff20: {
    0xff21: {
      value: Math.round(Ruuvitag.getEnvData().temp),
      readable: true,
      notify: true
    }
  }
});
setInterval(function () {
  NRF.updateServices({
    0xff20: {
      0xff21: {
        value: Math.round(Ruuvitag.getEnvData().temp),
        notify: true
      }
    }
  });
}, 1000);

What I am wondering however, is how I can connect to this service using a node.js application. I've been trying the espurino module but can't figure out how to use it to "scan" for GATT services. Using the bleat module I can find other BLE devices, but not my ruuvitag running espurino.

Any ideas what I might be getting wrong?

NB! I'm new to this whole BLE and GATT stuff, so I might be confused about a few things 😝

[espruino-discuss]

Posted at 2017-04-13 by AntiCat

I'm also a beginner, so you might get better responses from other users.

Gordon mentioned a change for the upcomming release (v92), see http://forum.espruino.com/comments/13525853/

you might need to add

0xff20

to the advertised services.

---

Posted at 2017-04-15 by user75772

Thanks @AnticaT !! I'll give that a try 😁

Turns out it was a rookie mistake of not disconnecting form the IDE 🙈😝 Working now! Using bleat.webbluetooth I am able to connect to the GATT service and pull characteristics and descriptor 🎉

Now I need to decode the data... Any ideas there? 😝

---

Posted at 2017-04-18 by @gfwilliams

Great! Glad you got it sorted!

In terms of decoding, given what you're doing you should hopefully just be receiving a 1-element array, where the single element is an integer value which is the temperature.

Not sure if it helps, but I've tended to use noble for interfacing via BLE. I think it's a bit more common so you might find documentation better.