New association request on second Central connection

[Armando]

Hi,

I'm encountering a strange problem with the nRF52832 when it works as Central with two bonded Peripherals connection.

In particular I'm able to secure the connection with the first Peripherals by calling the pm_handler_secure_on_connection() function as soon as the BLE_GAP_EVT_CONNECTED event is sent by the softdevice.

When I establish the connection with the second one Peripheral (a smartphone) I receive a new association request on the smartphone display, please consider that the device was previously bonded.

If I accept the new pairing with the device (by pressing “OK” on the smartphone display, I use the Just Works method) a new bonding occurs and the connection is secured, after a disconnection I have to pair again.

I use the scan with policy WHITELIST and I call the  sd_ble_gap_connect() function when the NRF_BLE_SCAN_EVT_WHITELIST_ADV_REPORT occurs.

Any idea about the problem?

[Armando]

Hi Edvin,

the problem occurs with the Periperal 1 connected. 

The problem now occurs with a specific smartphone.

I have disabled the PEER RANKS module by putting the #define PM_PEER_RANKS_ENABLED 0 and now the problem seems solved.

I have tried to set again the #define PM_PEER_RANKS_ENABLED 1 in order to acquire the sniffer trace but the problem doesn't occurs now.

I will send you the sniffer trace if the problem occurs again. Can you help me to understand the aim of the PEER RANK module?

[Edvin]

The peer rank is used to keep track of what peers that are used and in what order they were stored. Later this is used to know what peer to delete if your peer manager is full, but you want to store bonding information for a new device. It shouldn't really cause trouble like this. Perhaps the issue was just that one of your device used old bonding data, while the new one had deleted the bonding data.That would cause the bonding information to be invalid for the connection, and you need to perform the pairing again.

BR,

Edvin

[Armando]

Hi Edvin,

I used the pm_peers_delete() to delete the bonding information on the Central Device and Peripheral 1 and the nRF Connect App to delete the donding information on the Peripheral 2 before every test.

[Edvin]

Then the problem was probably that the bonding data was deleted, so the phone had to pair again, if you did this on every startup.