Why is my device name being truncated?

RE: Why is my device name being truncated?

Spacha — Wed, 17 Nov 2021 11:07:34 GMT

This is an old thread but thought to give an update in case someone stumbles upon this problem.

As mentioned before, the advertisement space is limited to 31 bytes including device appearance, name and other advertisement data. To have longer name, you need to get rid of something else (for example appearance, which gives some 4 bytes more space, or UUID, which gives a lot more).

Here's a demonstration of the advertising_init() function that is used to configure the advertisements. The comments show where you can give more space for the device name (appearance and UUID).

static void advertising_init(void)
{
    ret_code_t             err_code;
    ble_advertising_init_t init;

    memset(&init, 0, sizeof(init));

    init.advdata.name_type               = BLE_ADVDATA_FULL_NAME;
    init.advdata.include_appearance      = true; //<< To remove appearance, set this to false
    init.advdata.flags                   = BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE;
    
    //<< Comment out these 2 lines to remove the UUID from the advertisement
    //<< This gives a lot of space for the name.
    init.advdata.uuids_complete.uuid_cnt = sizeof(m_adv_uuids) / sizeof(m_adv_uuids[0]);
    init.advdata.uuids_complete.p_uuids  = m_adv_uuids;

    init.config.ble_adv_fast_enabled  = true;
    init.config.ble_adv_fast_interval = APP_ADV_INTERVAL;
    init.config.ble_adv_fast_timeout  = APP_ADV_DURATION;

    init.evt_handler = on_adv_evt;

    err_code = ble_advertising_init(&m_advertising, &init);
    APP_ERROR_CHECK(err_code);

    ble_advertising_conn_cfg_tag_set(&m_advertising, APP_BLE_CONN_CFG_TAG);
}

RE: Why is my device name being truncated?

Shimon_nohayo — Sun, 30 Jun 2019 11:21:43 GMT

I have a very similar problem,

Can you explain what do you mean by removing UUID?

Shimon

RE: Why is my device name being truncated?

Shimon_nohayo — Sun, 30 Jun 2019 11:18:27 GMT

I have a very similar problem,

Can you explain what do you mean by removing UUID?

Shimon

RE: Why is my device name being truncated?

Petter Myhre — Wed, 07 Feb 2018 12:15:13 GMT

31 bytes is maximum. If you want to have a longer device name you need to remove something else, UUID for example.

RE: Why is my device name being truncated?

purgoufr — Wed, 07 Feb 2018 07:52:29 GMT

I wrote function for advertising like that;

static void advertising_init(void)
{
    ret_code_t             err_code;
    ble_advertising_init_t init;

    memset(&init, 0, sizeof(init));

    init.advdata.name_type               = BLE_ADVDATA_FULL_NAME;
    init.advdata.include_appearance      = false;
    init.advdata.flags                   = BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE;
    init.advdata.uuids_complete.uuid_cnt = sizeof(m_adv_uuids) / sizeof(m_adv_uuids[0]);
    init.advdata.uuids_complete.p_uuids  = m_adv_uuids;

    init.config.ble_adv_fast_enabled  = true;
    init.config.ble_adv_fast_interval = APP_ADV_INTERVAL;
    init.config.ble_adv_fast_timeout  = APP_ADV_TIMEOUT_IN_SECONDS;

    init.evt_handler = on_adv_evt;

    err_code = ble_advertising_init(&m_advertising, &init);
    APP_ERROR_CHECK(err_code);

    ble_advertising_conn_cfg_tag_set(&m_advertising, APP_BLE_CONN_CFG_TAG);
}

But still I can not see full device name. When include_appearance is true I can see 4 charecter, When include_appearance is false I can see 8 charecter. I understand the data length calculation but I want to see full device name. So, Can I make the length more than 31 bytes? Or is there another way to see full device name?

RE: Why is my device name being truncated?

Eliot Stock — Fri, 18 Aug 2017 09:10:49 GMT

Bingo. Thank you.

RE: Why is my device name being truncated?

endnode — Thu, 17 Aug 2017 23:44:12 GMT

Here you go, \components\ble\common\ble_advdata.h file line #148 inside struct ble_advdata_t:

bool include_appearance; /**< Determines if Appearance shall be included. */

RE: Why is my device name being truncated?

endnode — Thu, 17 Aug 2017 23:40:37 GMT

There seems to be line #373 of \components\ble\ble_advertising\ble_advertising.c file saying:

p_advertising->advdata.include_appearance = p_init->advdata.include_appearance;

so I expect new parameter of some init structure called include_appearance which you just need to set properly when calling module. init or adv. start...

RE: Why is my device name being truncated?

Eliot Stock — Thu, 17 Aug 2017 23:39:37 GMT

Nothing's changed in what I'm attempting to advertise. What's changed is the SDK or the SD, I'm fairly sure. My question was, how do I omit the appearance from the advertising packet?

RE: Why is my device name being truncated?

endnode — Thu, 17 Aug 2017 23:33:43 GMT

On the picture you have (beside last Device Name AD) three AD objects. They come in Length-Tag-Value form where length counts also Tag. So by simple math 3+2+17+3(length bytes) = 25 bytes which leaves just 6 for whole Device Name AD element to be 31 in total. When you cut Length and Tag you have your 4 bytes so module is having this right. The question is which AD element has changed since previous version (and then by looking to changes in SDK code you should easily spot why and how to fix it).