Switch between Public address and Static Random address.

[yaho4624]

Power-on reset will require pairing again.

I found this happening by doing bt_id_reset().

Is there a problem with the way the BD address is initialized?

How to initialize BD address:

    bt_enable(NULL);

    if (IS_ENABLED(CONFIG_BT_SETTINGS))
    {
        settings_load();
    }

    bt_addr_le_t get_addr[CONFIG_BT_ID_MAX];
    size_t count = CONFIG_BT_ID_MAX;
    memset(&get_addr, 0, sizeof(get_addr));

    bt_id_get(get_addr, &count);
    if(get_addr[BD_ADDRESS_INDEX_RANDOM].a.val[5] == 0 && get_addr[BD_ADDRESS_INDEX_RANDOM].a.val[4] == 0 &&
        get_addr[BD_ADDRESS_INDEX_RANDOM].a.val[3] == 0 && get_addr[BD_ADDRESS_INDEX_RANDOM].a.val[2] == 0 &&
        get_addr[BD_ADDRESS_INDEX_RANDOM].a.val[1] == 0 && get_addr[BD_ADDRESS_INDEX_RANDOM].a.val[0] == 0){
        bt_id_create(&addr, nullptr);
    }else{
        bt_id_reset(BD_ADDRESS_INDEX_RANDOM, &addr, nullptr);
    }

Build Option:

CONFIG_BT_SMP=1
CONFIG_BT_ID_MAX=2
CONFIG_BT_SETTINGS=1
CONFIG_BT_KEYS_OVERWRITE_OLDEST=1

[Simonr]

Hi

Since bt_id_reset() removes any connections and pairing keys and it seems like the connection and bonding is done with the random static address. I don't really see why you call this function at all in your application if you want to keep the pairing information throughout a power-on reset. I'd recommend not calling it during your initialization.

Best regards,

Simon

[yaho4624]

Hi

I believe I need to use bt_id_reset() to update the static random address stored in NVM at startup.

Which API should I use to update static random address?

Regards,

yaho4624

[Simonr]

Is there a reason you want to change the static random address between boot-ups? The random address is actually the one that is pre-programmed from the factory. This is why it remains the same even though you erase your device and re-program it. It is expected that the random address stays the same between boot-ups.

Best regards,

Simon

[yaho4624]

Hi

I recognize the following about BLE BD addresses.
・Public Address：Addresses corresponding to hardware written in OTP, etc.
・Static Random Address：Address that changes with each boot to prevent the device from being tracked.

Is this perception wrong?

Regards,

yaho4624

[Simonr]

Hi

That's not quite it I'm afraid.

Public address: A public address is a fixed address that is programmed into the device at the manufacturer. This is globally unique and can not be erased.

Random addresses: Much more common, does not require registration with IEEE and can be manually configured by the user. It's either programmed within the device or created during run time. A random static address can be allocated and then fixed throughout the lifetime of the device. It can be altered at boot-up but doesn't have to be. 

More details here. Do you need to mask/change the address to not be tracked for some specific reason? Using a resolvable or non-resolvable random private address is more used as it changes periodically

Best reagrds,

Simon