nRF52833 MAC Address ramdonly changing while advertising

RE: nRF52833 MAC Address ramdonly changing while advertising

Amanda Hsieh — Mon, 27 Nov 2023 17:43:33 GMT

Hi,

See https://docs.zephyrproject.org/2.0.0/reference/logging/index.html#logging-strings

-Amanda H.

RE: nRF52833 MAC Address ramdonly changing while advertising

Learner — Tue, 21 Nov 2023 16:20:51 GMT

Hi Amanda,

Apologies for not responding earlier. I was away on holiday.

Unfortunately, there is no specific way to reproduce this anomaly. In fact, it happens very rarely, perhaps once in few months. I have added some logging in my code so that if/when it happens I will share with you the logs. Please have a look at the attached code I added.

/**
 *****************************************************************************************************************************************************
 *  @brief  Reads the static BLE MAC address of the device (local) from the structure
 *          bt_hci_vs_static_addr then compare to the one stored in the FICR register.
 *          If the two do not match then a device reset is forced.
 *
 *  @return Non Zero - If the BLE MAC address is read successfully
 *          Zero     - If the BLE MAC address is NOT read successfully
 *
 *****************************************************************************************************************************************************
 */
int bluetooth_read_static_addr( void )
{
    struct bt_hci_vs_static_addr    addr[1];
    static char                     addr_str[BT_ADDR_STR_LEN];
    int                             addr_count;

    addr_count = bt_read_static_addr( addr, 1 );

    if ( addr_count > 0 )
    {
        bt_addr_to_str( &(addr[0].bdaddr), addr_str, sizeof(addr_str) );
        LOG_INF( "BT addr: %s\n", &addr_str );
        LOG_HEXDUMP_DBG( addr_str,  sizeof(addr_str),   "Static Addr" );

        /* Read the source (local?) MAC address from the FICR register */
        {
            uint8_t mac_address[6];
            unsigned int device_addr_0 = NRF_FICR->DEVICEADDR[0];
            unsigned int device_addr_1 = NRF_FICR->DEVICEADDR[1];

            LOG_INF( "device_addr_0 = 0x%X, device_addr_1 = 0x%X", device_addr_0, device_addr_1 );

            const uint8_t* part_0 = (const uint8_t*)(&device_addr_0);
            const uint8_t* part_1 = (const uint8_t*)(&device_addr_1);

            /* According to the BLE spec on valid MAC addresses, in Core Spec 5.3, Vol 6,
             * Part B, §1.3.2.1, the two MSB of the address must be equal to 1 for a static
             * device address. If you don't do this, it will not match what you get with the
             * bt_read_static_addr() and bt_conn_get_info() functions.
             */
            mac_address[5] = part_1[1] | 0xC0;
            mac_address[4] = part_1[0];
            mac_address[3] = part_0[3];
            mac_address[2] = part_0[2];
            mac_address[1] = part_0[1];
            mac_address[0] = part_0[0];

            LOG_HEXDUMP_DBG( mac_address,  sizeof(mac_address),   "FICR Static Addr" );

            /* compare the local MAC address with the one read from the FICR register */
            if ( memcmp( &(addr[0].bdaddr.val), mac_address, sizeof(mac_address) ) )
            {
                 LOG_WRN( "Local MAC address does not match FICR" );

                /* Maybe we should also raise an alarm to flag this event */
                /*!!!TBD event_AddHighPriority(EV_HOME_STATION_RESET); */

                /* Reboot system with a software reset to retrieve the static random MAC address from the FICR */
                system_Reset();
            }
        }
    }

    return addr_count;
}

Are you interested in any other specific logs ?

I noticed when I run the above code I see these errors

<err> log: argument 0 in source bt log message "BT addr: " missinglog_strdup().

See below the output of my code in the debugger window.

[00:00:25.395,416] <inf> bt: BT addr: C7:2A:7D:C9:44:39

[00:00:25.395,416] <inf> bt: device_addr_0 = 0x7DC94439, device_addr_1 = 0x70F3072A
[00:00:25.409,820] <inf> bt: BT addr: C7:2A:7D:C9:44:39

[00:00:25.409,820] <inf> bt: device_addr_0 = 0x7DC94439, device_addr_1 = 0x70F3072A
[00:00:26.231,933] <err> log: argument 0 in source bt log message "BT addr: " missinglog_strdup().
[00:00:26.232,696] <err> log: argument 0 in source bt log message "BT addr: " missinglog_strdup().
[00:00:26.281,250] <inf> bt: BT addr: C7:2A:7D:C9:44:39

[00:00:26.281,280] <inf> bt: device_addr_0 = 0x7DC94439, device_addr_1 = 0x70F3072A
[00:00:27.281,158] <inf> bt: BT addr: C7:2A:7D:C9:44:39

[00:00:27.281,188] <inf> bt: device_addr_0 = 0x7DC94439, device_addr_1 = 0x70F3072A
[00:00:27.281,860] <err> log: argument 0 in source bt log message "BT addr: " missinglog_strdup().
[00:00:27.283,172] <err> log: argument 0 in source bt log message "BT addr: " missinglog_strdup().
[00:00:28.281,066] <inf> bt: BT addr: C7:2A:7D:C9:44:39

[00:00:28.281,097] <inf> bt: device_addr_0 = 0x7DC94439, device_addr_1 = 0x70F3072A
[00:00:29.281,250] <inf> bt: BT addr: C7:2A:7D:C9:44:39

[00:00:29.281,280] <inf> bt: device_addr_0 = 0x7DC94439, device_addr_1 = 0x70F3072A
[00:00:29.284,210] <err> log: argument 0 in source bt log message "BT addr: " missinglog_strdup().
[00:00:29.285,308] <err> log: argument 0 in source bt log message "BT addr: " missinglog_strdup().
[00:00:30.281,158] <inf> bt: BT addr: C7:2A:7D:C9:44:39

[00:00:30.281,188] <inf> bt: device_addr_0 = 0x7DC94439, device_addr_1 = 0x70F3072A
[00:00:31.281,005] <inf> bt: BT addr: C7:2A:7D:C9:44:39

[00:00:31.281,005] <inf> bt: device_addr_0 = 0x7DC94439, device_addr_1 = 0x70F3072A
[00:00:31.286,132] <err> log: argument 0 in source bt log message "BT addr: " missinglog_strdup().
[00:00:31.287,200] <err> log: argument 0 in source bt log message "BT addr: " missinglog_strdup().

It seems that the error is caused by this line of code,

LOG_INF( "BT addr: %s\n", &addr_str );

Can you please explain why this error is manifesting itself now and how to get rid of it. I use LOG_INF throughout my code but I don't see this error except in the code attached above,

Thank you.

Kind regards

Mohamed

RE: nRF52833 MAC Address ramdonly changing while advertising

Amanda Hsieh — Wed, 08 Nov 2023 16:49:36 GMT

Hi,

[quote user="Learner"]As I stated in a previous message, the MAC address is very infrequent. The device can go for months without changing its address. I believe the change is occurring during advertising. The reason I noticed the change is because our proprietary application running under Windows 10 could not connect to the device anymore over BLE. So, I checked the list of BLE devices that the application can see and noticed the MAC address of the device has changed.[/quote]

That sounds so strange. With the information you provided, it's hard to say what could cause the issue. If there are device logs, sniffer logs, or reproduction instructions, they might help investigate the issue.

Regards,
Amanda H.

RE: nRF52833 MAC Address ramdonly changing while advertising

Learner — Tue, 07 Nov 2023 16:15:37 GMT

Hi Amanda,

[quote userid="77782" url="~/f/nordic-q-a/105268/nrf52833-mac-address-ramdonly-changing-while-advertising/454517"]Could you explain the frequency and in what situation it changes the MAC address, in advertising or in connection?[/quote]

As I stated in a previous message, the MAC address is very infrequent. The device can go for months without changing its address. I believe the change is occurring during advertising. The reason I noticed the change is because our proprietary application running under Windows 10 could not connect to the device anymore over BLE. So, I checked the list of BLE devices that the application can see and noticed the MAC address of the device has changed.

[quote userid="77782" url="~/f/nordic-q-a/105268/nrf52833-mac-address-ramdonly-changing-while-advertising/454517"]Which type of address do you use?[/quote]

The default Static Random.

[quote userid="77782" url="~/f/nordic-q-a/105268/nrf52833-mac-address-ramdonly-changing-while-advertising/454517"]Do you use a sample as a base to develop your application?[/quote]

No, I am using our own application.

Note, this is not an isolated case; other users on Devzone have experienced the same problem, see Case ID: 313249.

[quote userid="77782" url="~/f/nordic-q-a/105268/nrf52833-mac-address-ramdonly-changing-while-advertising/454517"]Could you provide the sniffer log and device log when you observe the MAC address change?[/quote]

It is going to be difficult because it may take months before the MAC address change can occur.

Kind regards

Mohamed

RE: nRF52833 MAC Address ramdonly changing while advertising

Amanda Hsieh — Tue, 07 Nov 2023 15:16:01 GMT

Hi,

[quote user="Learner"]my device was sometimes changing its MAC address without going through a reset. [/quote]

Could you explain the frequency and in what situation it changes the MAC address, in advertising or in connection? Which type of address do you use? Do you use CONFIG_BT_PRIVACY?

Do you use a sample as a base to develop your application? If so, what is that?

Could you provide the sniffer log and device log when you observe the MAC address change?

-Amanda H.

RE: nRF52833 MAC Address ramdonly changing while advertising

Learner — Tue, 07 Nov 2023 14:36:10 GMT

Hi Amanda,

Thank you. 👏

But you still have not commented on why, before I added the option BT_LE_ADV_OPT_USE_IDENTITY, my device was sometimes changing its MAC address without going through a reset. According to Nordic's documentation this is not the expected behaviour.

Kind regards

Mohamed

RE: nRF52833 MAC Address ramdonly changing while advertising

Amanda Hsieh — Tue, 07 Nov 2023 14:18:58 GMT

Hi Mohamed,

I got it.

Please don't hesitate to contact me if you need further help. 🙂

Regards,
Amanda H.

RE: nRF52833 MAC Address ramdonly changing while advertising

Learner — Tue, 07 Nov 2023 10:03:35 GMT

Good Morning Amanda,

First, the MAC address change I reported does not happen often. In fact my device can go on for weeks and months without changing its MAC address.

Second, when it does change its MAC address it does it without going through a reset.

Finally, I have added the option BT_LE_ADV_OPT_USE_IDENTITY as you suggested. I will be monitoring this in the coming weeks and months.

Kind regards

Mohamed

RE: nRF52833 MAC Address ramdonly changing while advertising

Amanda Hsieh — Mon, 06 Nov 2023 20:48:30 GMT

[quote user="Learner"]This suggests that if I don't use BT_LE_ADV_OPT_USE_IDENTITY option then the random static address can change but only after a reset.[/quote]

That's correct. Do you still see it change the address with this option?

-Amanda H.

RE: nRF52833 MAC Address ramdonly changing while advertising

Learner — Mon, 06 Nov 2023 10:16:51 GMT

Good Morning Amanda,

Thank you for your valuable support.

Please bear with me if I keep asking you the same question over and over again. This is because I believe the information contained in the link you sent me contradicts your answer.

https://devzone.nordicsemi.com/guides/nrf-connect-sdk-guides/b/software/posts/building-a-ble-application-on-ncs-comparing-and-contrasting-to-softdevice-based-ble-applications

According to the link above,

"... Note if you want to advertise using local identity (static address not new address every time you reset) you should use BT_LE_ADV_OPT_USE_IDENTITY option. "

This suggests that if I don't use BT_LE_ADV_OPT_USE_IDENTITY option then the random static address can change but only after a reset. Or am I understanding this wrong?

Kind regards

Mohamed

RE: nRF52833 MAC Address ramdonly changing while advertising

Amanda Hsieh — Fri, 03 Nov 2023 20:32:46 GMT

Yes.

If you want to advertise identity you could use BT_LE_ADV_OPT_USE_IDENTITY.

-Amanda H.

RE: nRF52833 MAC Address ramdonly changing while advertising

Learner — Fri, 03 Nov 2023 14:35:40 GMT

Hi Amanda,

Thank you for your support.

OK, I will add BT_LE_ADV_OPT_USE_IDENTITY to the BT_LE_ADV_PARAM parameters.

Are you saying if I don't use the BT_LE_ADV_OPT_USE_IDENTITY option in BT_LE_ADV_PARAM then the device can randomly change its MAC address at runtime without a reset or a power cycle?

As I already stated I am seeing the device changing its MAC address without a reset or a power cycle. Is this possible?

Kind regards

Mohamed

RE: nRF52833 MAC Address ramdonly changing while advertising

Amanda Hsieh — Fri, 03 Nov 2023 13:13:43 GMT

As I explained in the previous reply, you should use BT_LE_ADV_OPT_USE_IDENTITY option in the BT_LE_ADV_PARAM. Check the Advertising section in this guide.

RE: nRF52833 MAC Address ramdonly changing while advertising

Learner — Thu, 02 Nov 2023 10:31:11 GMT

Good Morning Amanda,

[quote userid="77782" url="~/f/nordic-q-a/105268/nrf52833-mac-address-ramdonly-changing-while-advertising/453564"]What is your application? Do you mean in the advertising? If so, how do you set the BT_LE_ADV_PARAM?[/quote]

Yes, I am referring to the MAC address in the advertising. My device is a connectable peripheral that other devices should be able to connect to over BLE.

This is what I am doing to set the advertising parameters,

#define BT_LE_ADV_CONN_SLOW BT_LE_ADV_PARAM((BT_LE_ADV_OPT_CONNECTABLE | BT_LE_ADV_OPT_SCANNABLE), BT_GAP_ADV_SLOW_INT_MIN, BT_GAP_ADV_SLOW_INT_MAX, NULL)

#define BT_LE_ADV_CONN_FAST BT_LE_ADV_PARAM((BT_LE_ADV_OPT_CONNECTABLE | BT_LE_ADV_OPT_SCANNABLE), BT_GAP_ADV_FAST_INT_MIN_2, BT_GAP_ADV_FAST_INT_MAX_2, NULL)

/* ble_ad[] Can be up to 29 bytes */ static uint8_t ble_ad[HB_BLE_AD_BUFF_SIZE_MAX] = { 0U };

/* legacy advertisements up to 31 bytes Max */ static const struct bt_data ad[] = { BT_DATA(BT_DATA_MANUFACTURER_DATA, &ble_ad[0], sizeof(ble_ad)) };

/* ble_sd[] Can be up to 29 bytes */ static uint8_t ble_sd[HB_BLE_SD_BUFF_SIZE_MAX] = { 0U };

/* legacy advertisements up to 31 bytes Max */
static const struct bt_data sd[] = { BT_DATA(BT_DATA_MANUFACTURER_DATA, &ble_sd[0], sizeof(ble_sd)) };

...

/* Start advertising */ bt_le_adv_start(BT_LE_ADV_CONN_SLOW, ad, ARRAY_SIZE(ad), sd, ARRAY_SIZE(sd));

[quote userid="77782" url="~/f/nordic-q-a/105268/nrf52833-mac-address-ramdonly-changing-while-advertising/453564"]If you want to advertise using local identity (static address not new address every time you reset) you should use BT_LE_ADV_OPT_USE_IDENTITY option. [/quote]

Sometimes, I am seeing the advertising MAC address changing at runtime without the device going through a reset. According to the documentation this should not happen. Then when I reset the device it reverts back to its old address.

Can you please explain what could be causing this?

[quote userid="92434" url="~/f/nordic-q-a/105268/nrf52833-mac-address-ramdonly-changing-while-advertising/453532"]

According to Nordic's Academy Bluetooth-address page,

"A random static address can be allocated and then fixed throughout the lifetime of the device. It can be altered at bootup, but not during runtime. "

[/quote]

I am still unclear about how an application can change a static random address at boot-up. Please clarify.

Kind regards

Mohamed

RE: nRF52833 MAC Address ramdonly changing while advertising

Amanda Hsieh — Wed, 01 Nov 2023 16:51:13 GMT

Hi,

[quote user="Learner"] why am I seeing the random static MAC address of my device changing at runtime?[/quote]

What is your application? Do you mean in the advertising? If so, how do you set the BT_LE_ADV_PARAM? If you want to advertise using local identity (static address not new address every time you reset) you should use BT_LE_ADV_OPT_USE_IDENTITY option. Check the Advertising section in this guide.

[quote user="Learner"]

"Factory information configuration registers (FICR) are pre-programmed in factory and cannot be erased by the user. "

However, you said in your reply a random static address can be changed at bootup. Please explain how.

[/quote]

You can set the application to use the random static address at bootuping the application.

-Amanda H.

RE: nRF52833 MAC Address ramdonly changing while advertising

Learner — Wed, 01 Nov 2023 14:12:12 GMT

Hi Amanda,

Thank you for your prompt response.

I do not want to set the MAC address. I am happy to use the default address.

[quote userid="77782" url="~/f/nordic-q-a/105268/nrf52833-mac-address-ramdonly-changing-while-advertising/453515"]The default address used by the Bluetooth Stacks in nRF52833 is a random static address obtained from the DEVICEADDR[n] FICR registers (random number programmed during chip manufacturing).[/quote]

According to Nordic's Academy Bluetooth-address page,

"A random static address can be allocated and then fixed throughout the lifetime of the device. It can be altered at bootup, but not during runtime. "

So, why am I seeing the random static MAC address of my device changing at runtime?

Then when I restart (hard reset) the device it reverts back to the original MAC address.

As far as I can make out, I am not doing anything in my application code to change it.

Please explain what could be happening.

Also, according to Nordic's documentation,

"Factory information configuration registers (FICR) are pre-programmed in factory and cannot be erased by the user. "

However, you said in your reply a random static address can be changed at bootup. Please explain how.

Thank you.

Kind regards

Mohamed

RE: nRF52833 MAC Address ramdonly changing while advertising

Amanda Hsieh — Wed, 01 Nov 2023 13:29:27 GMT

Hi,

What type of address would you like to set? Bluetooth Low Energy comes with different address types, which you can read about in our DevAcademy course: https://academy.nordicsemi.com/topic/bluetooth-address/

Only public address type is liable to a fee (to the IEEE registration authority), random addresses can be used freely. The default address used by the Bluetooth Stacks in nRF52833 is a random static address obtained from the DEVICEADDR[n] FICR registers (random number programmed during chip manufacturing).

If you want to set Resolvable Private Addresses, you could use CONFIG_BT_PRIVACY.

Regards,
Amanda H.