Trouble with directed advertising

RE: Trouble with directed advertising

dingari — Tue, 07 Mar 2017 09:15:35 GMT

So, this is resolved. Thank you for your help Kristin.

To sum up:

Central OS's do not necessarily auto-connect to peripherals advertising in directed mode.
An exception is a peripheral implementing an HID keyboard or mouse, since the OS treats these devices differently.
Similar behavior for non-HID peripherals needs to be coded in the application itself.

RE: Trouble with directed advertising

FormerMember — Tue, 07 Mar 2017 08:12:12 GMT

Yes, that is almost correct: A whitelist does only limit from whom peripheral will accept a connect request. A whitelist can be used independently of the advertising type.

RE: Trouble with directed advertising

dingari — Mon, 06 Mar 2017 13:42:41 GMT

Ok, that's what I was starting to think. So the real difference between directed advertising and advertising with a whitelist is:

Directed: Advertise only to one specific peer and allow only that peer to send a connection request.
Whitelist: Advertise to at least one specific peer. (Anyone is allowed to send a connection request though?)

RE: Trouble with directed advertising

FormerMember — Mon, 06 Mar 2017 12:04:48 GMT

When using directed advertising, it is only the device specified in the directed advertising packet that is allowed to send a connect request to the advertiser.

If your device is not a HID device, I would think that you have to write own software for controlling/maintaining the link with your device. That is how it is for Windows, Android, and iOS as well.

RE: Trouble with directed advertising

dingari — Mon, 06 Mar 2017 11:15:58 GMT

Ok, I've now tried adding the HID service to my application configured as a keyboard and voilá, it auto-connects. It doesn't seem to have anything to do with directed advertising, since the connection isn't established until the peripheral enters fast advertising. So, what exactly are we doing directed advertising for?

But my peripheral is neither a keyboard or mouse. Is there no way of getting this behavior otherwise?

RE: Trouble with directed advertising

FormerMember — Mon, 06 Mar 2017 10:35:36 GMT

I would think that the behavior you are seeing is related to the HID service. In Windows, Android, iOS(?), devices with HID functionality is handled by the OS itself. So therefore, it would not be strange if Linux does the same.

Perhaps it is not enough for a a device to only have the HID appearance, perhaps it also needs the related services?

RE: Trouble with directed advertising

dingari — Mon, 06 Mar 2017 10:07:14 GMT

I've just now tried flashing the ble_app_hids_keyboard example to another peripheral device I have handy. It shows the same behavior as my Logitech mouse (connects automatically). I'm going to look through the code in the example and see if I'm missing anything. But could it be because it is an HID, and my peripheral does not register as an HID? Is the central treating them differently?

Edit: I tried setting my peripheral's GAP appearance to both Generic HID and HID Keyboard but it is not auto-connecting. So I guess it's not that.

RE: Trouble with directed advertising

FormerMember — Mon, 06 Mar 2017 09:39:24 GMT

What is the peripheral application you are using? Could you try to use one of the HID examples in the SDK, ble_app_hids_keyaboard or ble_app_hids_mouse? Does that change anything?

RE: Trouble with directed advertising

dingari — Mon, 06 Mar 2017 09:17:57 GMT

Hi Kristin, When I'm using my Logitech mouse, I don't specifically need to be scanning on the Linux central, it just connects. But I just tried this with my peripheral: Connect & bond -> restart peripheral -> open scanning dialog on Linux central, but no connection.

RE: Trouble with directed advertising

FormerMember — Fri, 03 Mar 2017 12:41:55 GMT

When your device starts to advertise directed advertising, could you double check that the Linux central is scanning?