Bluetooth Connection Management Between Smartphone and Device

[GC92ES]

Hello,

I need assistance with managing the Bluetooth connection between a smartphone (both Android and iOS) and my device, which functions as a keyboard and mouse (via touchpad). Specifically, I need to know if it is possible to connect and then completely disconnect (dissociate) a smartphone from my device directly from the device itself, without having to do so from the smartphone.

I have noticed that the only way to dissociate and prevent a previously paired device from reconnecting after a reset is to dissociate it from the smartphone. Despite my efforts, I have not been able to find a way to remove any possibility of pairing from my device. I believe this issue is related to the way smartphones handle Bluetooth connections, but I need confirmation to inform my client that it is indeed impossible to completely dissociate a smartphone from the product without going through the smartphone.

What advice can you offer on this matter? I have tried removing the bonding, but the smartphone remembers the connection and continues to reconnect with a different MAC address each time I forget the address from my device.

Thank you for your help.

[Sigurd]

Hi!

Android:

We have the Bond Management Service that can be used to request deletion of the bond on the other device.

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.6.1/nrf/samples/bluetooth/peripheral_bms/README.html

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.6.1/nrf/libraries/bluetooth_services/services/bms.html#bms-readme

iOS: 

iOS doesn't expose the Bond Management Service to the application. See this post:  RE: Issue about ble_app_bms 

[GC92ES]

Thank you for the response, I would like to focus on:

Requesting device: It is the device that sends the request to delete the bond (in this case, the client, i.e., the smartphone).
Server: It is the device that receives the request and performs the bond deletion operation (in this case, the nRF device).

I have checked the example you sent, so I would like to understand: is there, for example, no way to delete the bonding directly from my device with the nrf52840 chip, or do I always have to request it from the smartphone? If I wanted, for example, to remove the bonding with that device through disconnection or a button press, does this example allow me to do that?

[GC92ES]

What if I change the MAC address with which my device presents itself to the smartphone? Could it solve the automatic reconnection problem?

[Sigurd]

Hi!

GC92ES said:

is there, for example, no way to delete the bonding directly from my device with the nrf52840 chip

If you want to remove the bonding information that is stored on the nRF52 device, you can use the function bt_unpair() for that. See step 2 here: https://academy.nordicsemi.com/courses/bluetooth-low-energy-fundamentals/lessons/lesson-5-bluetooth-le-security-fundamentals/topic/blefund-lesson-5-exercise-2/

[GC92ES]

Hi Sigurd, I already did that.

But when the smartphone is connected to my device without performing a disassociation from the smartphone, the smartphone maintains the bond with my device. 
What I want to understand before asking myself if I'm doing something wrong is whether it is impossible to use my device to command the smartphone to disconnect from it. From my device with NRF52, I have no control over the connections maintained by the smartphone, correct?

Thank you for your help!

[Sigurd]

Hi!

Correct, you don't have control from the peripheral on what bonds the phone stores or not.

[GC92ES]

Thank you Sigurd. This is the answer I was looking for, so to ensure a secure connection, I only can enforce that the user dissociates from the device. This way, no other device can connect until the current device is no longer "bonded."

This approach will help maintain security by preventing unauthorized connections.