Android Question [B4X] BLE 2 - Bluetooth Low Energy

Nicolás Cieri · Jan 3, 2023

Hi, I have an app that works fine on many devices, but not on some.

To test, on one of the devices that doesn't work, try the Erel demo, BLEExample - B4a.

It's a Redmi A1.

It does the process as if it were scanning devices, but it never finds anything, that is, it never enters this part. "Manager_DeviceFound"

In the log, it doesn't show me any error.

Nicolás Cieri · Jan 3, 2023

The first difference between other smartphones, I get this error on Log...

(SecurityException) java.lang.SecurityException: Need android.permission.BLUETOOTH_SCAN permission for android.content.AttributionSource@edf38225: GattService registerScanner

So, I add the permission on manifiest and by rutine..

rp.CheckAndRequest("android.permission.BLUETOOTH_SCAN")
Wait For B4XPage_PermissionResult (Permission As String, Result As Boolean)
If Result = False Then
ToastMessageShow("No permission", True)
Return
End If

So, now I have the permission, no error.. but I can't see any device found in the sub "Manager_DeviceFound".

On high-end devices it seems to work fine, but on many it doesn't, it never goes into this "Manager_DeviceFound".

Thanks.

Erel · Jan 4, 2023

I've updated the example with the new permissions: https://www.b4x.com/android/forum/threads/b4x-ble-2-bluetooth-low-energy.59937/#content
I'm not sure whether it is related to the error you encountered but start with the updated example.

Nicolás Cieri · Jan 4, 2023

Hello Erel,

it stays like scanning, it's the same problem, it's not a permissions problem. The sub 'Manager_DeviceFound' never fires.

No error is shown, it's like it didn't find any Bluetooth devices, although there are many around and it works perfectly on other devices.

Nicolás Cieri · Jan 4, 2023

Maybe the device is not compatible because it is low-end?

But it's new, I bought it for testing because it has happened to me with various devices.

It's a Redmi A1.

Nicolás Cieri · Jan 4, 2023

The bluetooth of the phone works, because if I search for bluetooth devices from the phone settings if I can see all the ones it finds.

Only from the B4A apps, I can't see any, as if it didn't find any device.

emexes · Jan 4, 2023

Do the devices show up when you scan using nRF Connect app?

And if so: can you connect to any of them?

Nicolás Cieri · Jan 4, 2023

I have solved it, now it Works.

https://source.android.com/docs/core/connect/bluetooth/ble

Is there a way to detect when location is off??????, turning this on Works.

Location scanning

A device's location services can use Bluetooth to detect Bluetooth beacons and provide a more accurate location. This is how users enable the feature:

Go to Settings > Security & Location > Location.
Check that the Location On/Off toggle is in the On position.
Go to Mode.
Select either High accuracy or Battery saving mode.

Nicolás Cieri · Jan 4, 2023

or ask the user to activate it, from the application?

emexes · Jan 4, 2023

Nicolás Cieri said:
Is there a way to detect when location is off??????

Nicolás Cieri said:
or ask the user to activate it, from the application?

I thought these were covered in the demo app.

Maybe the requirements changed at some point along the Android timeline.

Nicolás Cieri · Jan 4, 2023

No, it's not covered in the "Demo", because even if it says if I allow it, it doesn't really change this permission.

I had to change this permission manually in the phone settings.

emexes · Jan 4, 2023

Nicolás Cieri said:
No, it's not covered in the "Demo"

OK, if you started with the recently-updated example per https://www.b4x.com/android/forum/threads/b4x-ble-2-bluetooth-low-energy.145229/post-920564 and that doesn"t cover making sure necessary settings are enabled, then I am with you in thinking that pointing the user in the right direction would be a Good Thing. ?

I am on a tablet at the moment = can't check further until back in front of PC tomorrow.

Nicolás Cieri · Jan 4, 2023

Thanks emexes, but I confirm, this permission is not not covered in the "Demo".

emexes · Jan 4, 2023

Nicolás Cieri said:
or ask the user to activate it, from the application?

It might be useful to check how other apps, eg nRF Conect, handle the same situation

the more your app keeps to the "normal" way of doing things, the fewer user queries you're likely to receive ?

emexes · Jan 5, 2023

emexes said:
It might be useful to check how other apps, eg nRF Conect, handle the same situation

And the answer to that is:

emexes · Jan 5, 2023

Nicolás Cieri said:
or ask the user to activate it, from the application?

This tutorial post:

https://www.b4x.com/android/forum/threads/gps-tutorial.6592/

contains example code:

B4X:

StartActivity(Starter.GPS1.LocationSettingsIntent)     'Will open the relevant settings screen.

which sounds like it's in the right area as we're looking for too.

Also this thread https://www.b4x.com/android/forum/threads/gps-and-quick-settings-screen.38106/ albeit that is 8 years ago from the days of steam-powered smart phones ? and plenty may have changed since then.

Erel · Jan 5, 2023

The only way to enable location services from inside the app: https://www.b4x.com/android/forum/threads/fusedlocationprovider-resolution-dialog.111652/#content

Nicolás Cieri · Jan 5, 2023

Thanks emexes.

Erel, That was the solution. Thanks a lot.

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