Advertising name change on the fly

RE: Advertising name change on the fly

Karl Ylvisaker — Tue, 30 Jan 2024 10:37:47 GMT

Hello Jeremy,

Please follow the approach detailed in this blogpost on how to dynamically update your advertising payload in the nRF5 SDK, and let me know if you encounter any issues or questions! :)

Best regards,
Karl

RE: Advertising name change on the fly

jhubbard13579 — Tue, 30 Jan 2024 00:16:05 GMT

I am seeing this exact problem. Is there an update on a solution to this?

RE: Advertising name change on the fly

Karl Ylvisaker — Fri, 15 May 2020 10:13:38 GMT

Hi again Dmitry,

I did some more testing, and uncovered that the advertising changes to shortened name version after a few iterations - which is why the name gets "stuck" at a shorter length.
I will look into the reason for why this happens, thank you for pointing this out to me.

Best regards,
Karl

RE: Advertising name change on the fly

Karl Ylvisaker — Wed, 13 May 2020 14:02:18 GMT

Hello again Dmitry,

With the details you provided I was finally able to recreate the behavior on my end.
I see now that changing from a longer name to a shorter one, and then back to the longer one only yields the same length as the shortest one used - this is not the intended behavior.
I will be discussing this with a colleague tomorrow.
I'll update you on what he says tomorrow.

Best regards,
Karl

RE: Advertising name change on the fly

Karl Ylvisaker — Tue, 12 May 2020 13:23:45 GMT

Hello Dmitry,

[quote user="dmitry_t"]Well, my bad. It seems it was somehow related to read back protection is set on my device. Now it's ok and I was able to use nRFConnect.[/quote]

I am glad you were able to resolve your issue with nRF Connect! I am however not sure that I fully understood what you meant by the readback part begin the cause of this.

Thank you for the very detailed description. I have allocated time to replicate this, using all the information you have provided, tomorrow. I can not see any reason why it should behave like this, especially considering the workaround you found.

I am looking forward to resolving this issue.

Best regards,
Karl

RE: Advertising name change on the fly

dmitry_t — Mon, 11 May 2020 06:16:04 GMT

Hi Karl,

[quote userid="87869" url="~/f/nordic-q-a/60843/advertising-name-change-on-the-fly/249009"]That does sound strange.[/quote]

Well, my bad. It seems it was somehow related to read back protection is set on my device. Now it's ok and I was able to use nRFConnect.

I removed my workaround in order to check by using nRFConnect how my device advertises itself when I change the adv name. Briefly, it behaves exactly the same I described earlier. Here are a few screenshot.

First I set the name CHWC12345, everything is ok

Then, I set the name as CHWC987, so far so good

Finally, I set the name as CHWC12345 again, however now I see just CHWC123

Thanks,
Dmitry.

RE: Advertising name change on the fly

Karl Ylvisaker — Fri, 08 May 2020 14:59:38 GMT

Hello Dmitry,

[quote user="dmitry_t"]Installation was successfully completed. The problem is when I tried to select my board from the list I have error: "Unsupported device with serial number '000685087661' and traits ["serialport"]". Most likely I forgot to do something, but I followed the video guide on your internet site.[/quote]

That does sound strange.
Could you open another ticket detailing the nRF Connect install issue? If you were following a tutorial or video when it happened, it would be great if you could pinpoint where it goes wrong.

[quote user="dmitry_t"]No hurry. My workaround works pretty well now.[/quote]

I am happy that you workaround solved the issue. I will look into this on monday, and try to replicate the exact behavior that you describe.

Best regards,
Karl

RE: Advertising name change on the fly

dmitry_t — Wed, 06 May 2020 07:14:25 GMT

Hello Karl,

[quote userid="87869" url="~/f/nordic-q-a/60843/advertising-name-change-on-the-fly/248286"] I read online that you will need to turn off and on again the Bluetooth functionality in windows to be certain that it is not using cached device names.[/quote]

I think it's ok with the list, because other nrf board, I use as data receiver, scans the same name and cannot find it, due to transmitter cuts the name.

[quote userid="87869" url="~/f/nordic-q-a/60843/advertising-name-change-on-the-fly/248286"]is there a problem with the installation that I might be able to help you resolve?[/quote]

Installation was successfully completed. The problem is when I tried to select my board from the list I have error: "Unsupported device with serial number '000685087661' and traits ["serialport"]". Most likely I forgot to do something, but I followed the video guide on your internet site.

[quote userid="87869" url="~/f/nordic-q-a/60843/advertising-name-change-on-the-fly/248286"]I will attempt to replicate this behavior tomorrow, with the procedure you have specified. I will get back to you with my results.[/quote]

No hurry. My workaround works pretty well now.

Thanks,

Dmitry

RE: Advertising name change on the fly

Karl Ylvisaker — Tue, 05 May 2020 16:23:15 GMT

Hello Dmitry,

[quote user="dmitry_t"]Correct. As soon as I fix length of adv name the board started working as expected -- other board is able to match advertising name, and I see exactly same name in Windows list. Sorry, I didn't have enough time to figure out how to use nRF Connect, I faced with some difficulties.[/quote]

I understand. I would still highly recommend making use of the nRF Connect - is there a problem with the installation that I might be able to help you resolve?
I am not familiar with using the windows bluetooth list, but I read online that you will need to turn off and on again the Bluetooth functionality in windows to be certain that it is not using cached device names.

[quote user="dmitry_t"]No it's not in preset list. In current version of the code I generate it as follows: fixed prefix which is constant string of 4 characters "ABCD" + ID of the device (uint32_t) which is converted to hex string with leading zeros the length is 12 chars, so overall I have the 16 chars in the string, however I had to add one extra character, otherwise I see only 15 chars in the broadcast adv name. To make the long story short this is the principle I use to compose the name string[/quote]

Thank you for the clarification.

[quote user="dmitry_t"]Sorry, I'm under NDA, but I believe it may be reproduced by following way:[/quote]

I understand. I will attempt to replicate this behavior tomorrow, with the procedure you have specified. I will get back to you with my results.

Let me know if you at any time would like me to make this ticket private.

Best regards,
Karl

RE: Advertising name change on the fly

dmitry_t — Tue, 05 May 2020 06:16:04 GMT

Hi Karl,

[quote userid="87869" url="~/f/nordic-q-a/60843/advertising-name-change-on-the-fly/247908"]but you said this workaround ensures that the full name is showing up?[/quote]

Correct. As soon as I fix length of adv name the board started working as expected -- other board is able to match advertising name, and I see exactly same name in Windows list. Sorry, I didn't have enough time to figure out how to use nRF Connect, I faced with some difficulties.

[quote userid="87869" url="~/f/nordic-q-a/60843/advertising-name-change-on-the-fly/247908"]Could you tell me how you do the name updates? Are you using the ble_gap_device_name_set() function, or are you stopping advertising, changing adv parameters and starting advertising again?[/quote]

I do it as I showed in function adv_start() in my original post. Stop advertising first, use ble_gap_device_name_set() to change parameters, set adv parameters using advertising_data_set() function and start adv again. This sequence I took from this thread.

[quote userid="87869" url="~/f/nordic-q-a/60843/advertising-name-change-on-the-fly/247908"]Could you also tell me how you are generating your new names? Is it following a preset list, or are you splicing a string with randoms numbers, or similar?[/quote]

No it's not in preset list. In current version of the code I generate it as follows: fixed prefix which is constant string of 4 characters "ABCD" + ID of the device (uint32_t) which is converted to hex string with leading zeros the length is 12 chars, so overall I have the 16 chars in the string, however I had to add one extra character, otherwise I see only 15 chars in the broadcast adv name. To make the long story short this is the principle I use to compose the name string

#define DEVNAMEPREFIX "ABCD"
char my_name[17] = {0};
snprintf(my_name, 17, "%s%012lx", DEVNAMEPREFIX, id); //id is hardcoded uint32_t

The length of the composed string for further use in sd_ble_gap_device_name_set can be obtained by two ways (I actually tried both, they both work) -- 1. use strlen(my_name), 2. use the value snprintf returns.

[quote userid="87869" url="~/f/nordic-q-a/60843/advertising-name-change-on-the-fly/247908"]Are you able to share your entire project code, so I attempt to replicate this on my end?[/quote]

Sorry, I'm under NDA, but I believe it may be reproduced by following way:

Start advertising with some generated name
Replace the name on the fly by shorter name
Replace the name on the fly by longer name --> at this step my second board cannot make a connection because adv name does not match to expected one, due to the first board cuts advertising name.

Thanks,

Dmitry.

RE: Advertising name change on the fly

Karl Ylvisaker — Mon, 04 May 2020 13:49:38 GMT

Hello again,

Sorry for my late reply - there was a national holiday here in Norway, but we are back now.

I looked over you code and I could not immediately see something wrong with it.
As far as I know, snprint() will normally append a null terminator at the end of its output, which we do not want in this case - but you said this workaround ensures that the full name is showing up?

Could you tell me how you do the name updates? Are you using the ble_gap_device_name_set() function, or are you stopping advertising, changing adv parameters and starting advertising again?
Could you also tell me how you are generating your new names? Is it following a preset list, or are you splicing a string with randoms numbers, or similar?

[quote user="dmitry_t"][/quote]

which gives me fixed length of adv string.

But I still don't understand why it behaves as it is.

No, changing of the device name should be completely fine as long as you do not exceed the 31 byte limit for advertising packets.

[quote user="dmitry_t"]Did I get it right that I need one extra board to monitor BLE traffic? At the moment I have only two nrf52833 pca10100 boards. I also checked sniffer tool binaries and did not find suitable for my board.[/quote]

Yes, you will need an additional device to act as the sniffer, and it needs to be one of the supported boards.
If you are using the nRF Connect desktop application now, then it is still a large improvement, and it will make things much easier than using the native Windows applications.
Please make sure to clear the found devices page when looking for the updated names, to ensure you are not seeing a cached version of the device.

[quote user="dmitry_t"]Two nrf boards are connected. windows pc is used just for checking the advertising name.[/quote]

Thank you for clarifying.

Are you able to share your entire project code, so I attempt to replicate this on my end?
If you would like, I could convert this ticket to a private one - so that it is only viewable to you and the support staff here at Nordic Semiconductor - if the code is sensitive.

Best regards,
Karl

RE: Advertising name change on the fly

dmitry_t — Thu, 30 Apr 2020 12:01:53 GMT

Alright, I did more tests and can be more specific now.

It seems like the length of the the advertising name must be not less than it was previous time.

For example, if I have "device_12345" as adv name I see "device_12345" in windows10 bluetooth device list. Now if I change it as "device_98765" I also see same string in the list. Next, If I change it to "device_456" I see same name again, but now if I change it as "device_67890" I'll see only "device_678". All changes were done on the fly. Is this expected behavior?

So, the issue not related to any connection with other board.

The workaround I implemented is:

snprintf(m_my_advertising_name, MAX_DEV_NAME_LEN, "%s%05lu", DEVNAMEPREFIX, id);

which gives me fixed length of adv string.

But I still don't understand why it behaves as it is.

RE: Advertising name change on the fly

dmitry_t — Thu, 30 Apr 2020 08:20:20 GMT

Hi Karl,

Thanks for reply.

> Have you got the nRF Connect for Desktop application, or a Sniffer tool installed?

No I have not. I just checked the sniffer tool and nRF Connect desktop application. Did I get it right that I need one extra board to monitor BLE traffic? At the moment I have only two nrf52833 pca10100 boards. I also checked sniffer tool binaries and did not find suitable for my board.

> Which device is connected - the two nRF boards, or an nRF board and the windows pc?

Two nrf boards are connected. windows pc is used just for checking the advertising name.

Two boards can connect base on advertising name match (event NRF_BLE_SCAN_EVT_FILTER_MATCH happens), after that some data is transferred followed by disconnect procedure.

My code mostly based on examples/ble_central_and_peripheral/experimental/ble_app_att_mtu_throughput.

RE: Advertising name change on the fly

Karl Ylvisaker — Thu, 30 Apr 2020 07:30:37 GMT

Hello,

[quote user=""]I check device name in Bluetootth devices list in Windows10 to make sure the name is correct.[/quote]

Have you got the nRF Connect for Desktop application, or a Sniffer tool installed?
If you have, you can check more accurately what the board is actually advertising - I would highly recommend using one of the above, instead of the windows Bluetooth device list. Could you try one of the two, and let me know if the board still fails to update its advertising information?

[quote user=""]Say, after disconnection I set name "device_98765", but in the Bluetooth device list in Windows10 I see only "device_9". I have no idea why.[/quote]

This might be the result of Windows caching the device information from its previous connection.

[quote user=""]But once another nrf board connected, transferred data and disconnected, it's no longer possible to set new advertising device name.[/quote]

If you are able to confirm with the nRF Connect or nRF Sniffer tool that the advertised name does not change, could you elaborate some more on the events leading up to this? I am not sure I understood the connection sequence you describe. Which device is connected - the two nRF boards, or an nRF board and the windows pc? -, and what data is being transferred?

Best regards,
Karl