Renaming connected device

[Thomas U]

Hello Nordic

I am developing a sensor application using nRF52833. The user must be able to connect to the nRF52833 and give it a new name. I have a name characteristic that the user will write the new name to. When the nRF52833 receives the new name, it should disconnect and start advertising the new name. Then the user will reconnect using the new name.

I have read a lot of post on this subject. But none of them seems to work for me. I get the general idea about how to do it:

• Set the new name using sd_ble_gap_device_name_set
• Restart the advertising, several ways to do it are described in posts

I am using: SDK 17.1.0

Code starting point: examples\ble_peripheral\ble_app_template

I can rename the nRF52833, but nothing happens until a power cycling takes place.

This is my code:

In the main file I check whether the user has requested a new name. Then I set the new name and run the advertisement initialization again (suggested in this forum)

 if (is_new_device_name_requested()) // if the user has requested a new name for this sensor, then go ahead and set it

    {

        NRF_LOG_INFO("setting new device name");

        set_device_name(DEVICE_NAME);

        advertising_init();

  }

The set_device_name function is shown below:

void set_device_name(uint8_t* first_name)
{
ret_code_t err_code;
ble_gap_conn_sec_mode_t sec_mode;

BLE_GAP_CONN_SEC_MODE_SET_OPEN(&sec_mode);

memset(full_device_name, 0, sizeof full_device_name);
strcpy(full_device_name, first_name);
strcat(full_device_name, general_par.last_device_name);

err_code = sd_ble_gap_device_name_set(&sec_mode,
(const uint8_t *)full_device_name,
strlen(full_device_name));
APP_ERROR_CHECK(err_code);
general_par.is_new_device_name_wanted = false;
}

The advertising_init function is shown below:

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;
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_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);
}

[Hieu]

Hi Thomas,

Please know that we got your ticket. I cannot see anything immediately wrong here. I will take a closer look at it this morning and come back with an estimation later in the afternoon, unless someone from the community have already helped you by then.

Hieu

[Thomas U]

Hi Hieu

Thank you for answering me so fast. My application doesn’t necessarily require that the NRF52 should disconnect and advertise the new name, when renamed. I would be sufficient that it advertises the new name after a disconnect. When I perform a disconnect from the BLE central the NRF52 do not advertise at all. It is silent until after a power cycle.

[Hieu]

Hi Thomas,

My apology that I didn't follow-up yesterday as I said I would. I will try to pinpoint what is wrong by the end of tomorrow, Thu 08 Dec.

[Hieu]

Hi Thomas,

Are you changing the name while advertising? I take a look at the design of the ble_advertising module and it seems it isn't intended for the "start > stop > update > start again" update method.

The module does come with a function that is intended to help updating advertising data. It is ble_advertising_advdata_update().

I have tested using your code, adjusting the bit that use advertising_init() to use that function instead, and I can successfully get the advertising device name to update.

One of our colleagues, Karl, also wrote a great blog on updating advertising data, which include a sample code using that function in nRF5 SDK v17.1.0. You can find it here:  How to update advertising data dynamically using BLE Advertising library 

Could you please tweak things to use that function instead, and let me know if it works/does not work?

[Thomas U]

Hi Hieu

I am changing the name while being in connected mode. I am now using: ble_advertising_advdata_update(). 

From Karls example I have used and modified the timer handler: static void adv_data_update_timer_handler(void * p_context). I have converted it to a normal function because i do not need timers to trigger it. I have deleted the manufacturer specific data, because I solely want to change the device name. The modified code is shown below:

static ble_advdata_t new_advdata;

static void adv_data_update(void)
{
    ret_code_t                  err_code;

    NRF_LOG_INFO("Updating advertising data!");
    
    err_code = ble_advertising_advdata_update(&m_advertising, &new_advdata, NULL);
    APP_ERROR_CHECK(err_code);  
    
    NRF_LOG_INFO("Advertising data updated!");
}

While the NRF52833 is connected a new name is given by the user and the function below is called:

void set_device_name(uint8_t* first_name)
{
    ret_code_t              err_code;
    ble_gap_conn_sec_mode_t sec_mode;

    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&sec_mode);
    
    memset(full_device_name, 0, sizeof full_device_name);
    strcpy(full_device_name, first_name);
    strcat(full_device_name, general_par.last_device_name);

    err_code = sd_ble_gap_device_name_set(&sec_mode,
                                          (const uint8_t *)full_device_name,
                                          strlen(full_device_name));
    APP_ERROR_CHECK(err_code);
    general_par.is_new_device_name_wanted = false;
}

Then I proceed to call the adv_data_update function. I have tried calling it from two code locations:

1. Subsequent to the device name change

2. After disconnection has occurred

Below i 2 code snippets showing where I have called adv_data_udpate.

    if (is_new_device_name_requested()) // if the user has requested a new name for this sensor, then go ahead and set it
    {
        NRF_LOG_INFO("setting new device name");
        set_device_name(DEVICE_NAME);
        adv_data_update();

/**@brief Function for handling BLE events.
 *
 * @param[in]   p_ble_evt   Bluetooth stack event.
 * @param[in]   p_context   Unused.
 */
static void ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context)
{
    ret_code_t err_code = NRF_SUCCESS;

    switch (p_ble_evt->header.evt_id)
    {
        case BLE_GAP_EVT_DISCONNECTED:
            NRF_LOG_INFO("Disconnected.");
            adv_data_update();
            // LED indication will be changed when advertising starts.
            break;

The result is the same. When I disconnect the NRF52833 will not advertise. A power cycle is needed before i start advertising again. Thank you for your help.