How to handle a sudden disconnection of the master on the peripheral (NRF8001)

[Omnia]

Hello Nordic team,

I am working on a BLE RedBearLab shield (nrf8001) mounted on an Arduino board.

Consider that a connection is correctly made from a Master app to my nrf8001 (Peripheral) . The master have already subscribed to an advertising characteristic (with a notify mod) and every thing is fine.

If the Master suddenly stop running (for exemple if the Master is out of battery or just crashed…) I would like to know the proper way to inform my nrf8001 board that the subscription of the advertising characteristic previously made is not valid anymore.

How can I do that ? My first idea was to sent a packet every X period of time from my peripheral board with an acknowledgement and if I haven’t received any response before a pre-determined time , I can consider that the connection is lost. Is there any other/better way to do that ? How can I know that there is no more valid connection on the peripheral side?

Thanks, Regards,

[Omnia]

Thanks for your answer,

All your sentences are correct, I mean, it's what is happening.

• I not using any encryption on the link.
• The master has to subscribe again (At each reconnection) to the Characteristics that are Notify or Indicate.
• The subscription has to be done for every connection from the master when encryption is not used.

And effectively, if the master close properly the connection, the peripheral receive an ACI Disconnected Event to signal that the app has finished.

However, even if I think I understand what you said, what is the link between this and my problem? My goal is to receive an event from the peripheral side when I lost the master. To be able to get that, do I have to do an encryption on the link (for example a paring without man-in-the-middle (MITM) protection would work)?

I am little bite confused about what you call encryption. Do you have any example or document to help me to understand this concept and how it will resolve my problem?

Thanks,

[Ole Morten]

I'm not sure I understand what you mean; as I said initially you'll get a DisconnectedEvent once the Central device goes out of range or disconnects the link in any way, no matter if it crashes, runs out of battery or anything else. At that time, you can restart advertising again by sending the Connect command to the nRF8001. No encryption is needed for this.