S110 role switching

RE: S110 role switching

Ole Morten — Thu, 24 Oct 2013 09:02:51 GMT

I'm afraid I can't comment on that, so you should get in touch with our sales managers to get information on upcoming features. If you don't have their contact information, send me a PM with your location.

RE: S110 role switching

cocoa — Thu, 24 Oct 2013 08:07:15 GMT

Hi Ole,

any news about an implementation of Observer role in S110 ?

bye.

-c

RE: S110 role switching

Ole Morten — Thu, 24 Oct 2013 07:55:18 GMT

You would have to have some method to get the device to clear its existing Central, and be ready for a new one, for example a button press. But I'm not sure I see how this is any different for the dual-role-scenario.

If however you have more questions on this, I'd suggest that you create a support case, since that is more targeted towards this kind of discussion.

RE: S110 role switching

Ole Morten — Thu, 24 Oct 2013 07:53:43 GMT

You're right that it won't hide the device completely, but since you have full control over the advertising data, you can choose to just not include any data at all if you already have a bond and are advertising with whitelist. This will let other devices see that there is some advertiser here, and possibly locate it by using RSSI measurements, but they will not be able to connect or to get any information from it.

The reason that switching would be complicated is that both of the devices will have to be dual-role, and both have to switch at the same time, so there have to be some channel for them to coordinate this switch. If we talk about a tag and a phone, it would have to work something like this:

The tag continuously scans for advertisement packets, as a Central.
The phone continuously sends out advertisement packets, as a Peripheral.
When the phone comes into range, the tag would most likely have to connect to the phone to tell it to switch roles.
The phone would then start scanning for the tag.
The tag would have to start advertising.
The phone can then connect and they can transmit data.

Without the role switching, it would instead work like this:

The tag is continuously advertising with whitelist.
Once the phone comes into range, it can connect and data transfer can start.

The major problem with the first solution, in addition to the complicity, is that scanning is a power-hungry operation as compared to advertising. It requires the radio to be on in RX mode for relatively long periods of time.

However, since the roles that affect data transfer (GATT Server and GATT Client) is unrelated to the roles of Peripheral/Central, and as such, with the first solution, it would be possible to stop at step 3 and exchange data. This could be an option, but the current consumption is still a problem.

RE: S110 role switching

Leon Schmetz — Thu, 24 Oct 2013 07:45:45 GMT

And in case I have to exchange a master, how do I then get a new master on the whitelist? Especially when the slave is buried somewhere.

RE: S110 role switching

Leon Schmetz — Thu, 24 Oct 2013 07:41:09 GMT

Whitelisting does not hide the device from everybody passing. But if it is the best that can be done, it will have to do. After reading Robin Heydons book I did not think it would be so hard to implement.

RE: S110 role switching

Ole Morten — Thu, 24 Oct 2013 07:36:46 GMT

For questions on future features, you should talk to your sales representative.

However, this kind of role-switching is an extremely complicated way to achieve what you want, and I'd strongly recommend you to instead look into using whitelisting. As far as I can see, you should be able to achieve the exact same behavior as seen from the user's perspective, but without all the complications that this role-switching will infer.

If there is anything in particular that's unclear on how whitelisting works, I'd recommend you to search around a little here, since it has been discussed several places: https://devzone.nordicsemi.com/index.php/search?query=whitelist&option=com_easydiscuss&view=search&Itemid=479

If there is anything that is still unclear, I'd be happy if you could post it as a separate question, since that will make it easier for us to find it and answer.

RE: S110 role switching

Leon Schmetz — Wed, 23 Oct 2013 15:08:45 GMT

Heaving read this thread, I can tell you, I am looking for the exact same setup where devices switch roles. Let me explain. We are developing a device that will have a ble interface to configure settings. We want this device to be hidden. Hence we would like to implement the observer role. Now when a specific party advertises itself, this device should open up for this party only. For functional reasons we believe that roles must be switched to get the configuration job done.

So my question is, can this functionality be added to the softdevice?

thank you,

Leon

RE: S110 role switching

cocoa — Sat, 29 Jun 2013 13:14:50 GMT

Hi Ole, accepted as answer and, as suggested, I will create a new post about Manufacturer specific data. Thanks. -c

RE: S110 role switching

Ole Morten — Sat, 29 Jun 2013 10:21:06 GMT

If you have two devices, both capable of switching roles, you might be able to get this working, but then again, I'm having trouble understanding what you achieve by all this trouble, as it seems pretty excessive to me.

I'd absolutely looking into whitelisting and the addition of manufacturer specific data to solve this in some other way. Whitelisting will require that you either have been bonded with the other device, or that you know its Bluetooth address. Manufacturer specific data is data that you can add to your advertisement package, which the Central then can read for specific information about your peripheral. If you need further information on either of these, it might make most sense to post it as a separate question.

RE: S110 role switching

cocoa — Fri, 28 Jun 2013 09:24:46 GMT

If the device had the chance to switch from central to peripheral (and the other device from peripheral to central) do you think it could be possible ? Let me to be more clear : Device A is running as central - (scanner) Device B wake up as peripheral, start to advertise Device A recognize the right advertising , communicates the ok to B, changes role to peripheral Device B (as receives the OK) switch to Central

at the end : Device A is a Peripheral/Server Device B is a Central/Client

Admitting nRF51822 be a Central in a new release of S110.

Thank you.

RE: S110 role switching

Ole Morten — Fri, 28 Jun 2013 06:50:58 GMT

No, this isn't possible with the S110, and not actually with any BLE Peripheral or Central device as far as I can see.

You have to be advertising to be able to receive a connection request, since a Peripheral will only listen for packets right after having sent an advertisement. Also, a Scanner will not send any packets but only listen passively if it doesn't first receive any advertisement packages, so unfortunately I don't see how your suggested scheme could work with any BLE device.

RE: S110 role switching

cocoa — Fri, 28 Jun 2013 06:03:08 GMT

The aim is having a passive , non advertising, peripheral, who reacts only to a specific active scanning message without having a previous bonding.

Is it possible with S110 ?

RE: S110 role switching

Ole Morten — Fri, 28 Jun 2013 05:13:07 GMT

If the aim is to connect to a specific Central device, with which you have already bonded, you should look into whitelisting. This is the exact functionality this offers. For an example of how this can be implemented, I'd recommend you to take a look on the ble_app_proximity. It uses a bond manager API function to get a whitelist, which it then uses when advertising.

The S110 can do the Peripheral and Broadcaster roles only, and can not behave as an Observer. Also, an Observer would not normally be able to see other Central devices, so I'm not sure how useful that would have been.