Help with understanding advertising choices

[Keith Brafford]

I am building a project that is based on the custom service example https://github.com/bjornspockeli/custom_ble_service_example but I don't like how it advertises in a way that only leaves 4 characters for my device name.

I grafted on the advertising method from ble_app_blinky as an alternate advertising function in my app (so I can go back and forth), and I get the full device name to show up in nRFConnect.  It doesn't work 100% yet--it won't launch into advertising again after a disconnect--but other than that think I like the result better.  Can someone help me understand why the blinky method leaves more space for the name, and what I am giving up by doing it that way?

Here's my "alt" advertising functions:

static uint8_t m_adv_handle = BLE_GAP_ADV_SET_HANDLE_NOT_SET; /**< Advertising handle used to identify an advertising set. */
static uint8_t m_enc_advdata[BLE_GAP_ADV_SET_DATA_SIZE_MAX]; /**< Buffer for storing an encoded advertising set. */
static uint8_t m_enc_scan_response_data[BLE_GAP_ADV_SET_DATA_SIZE_MAX]; /**< Buffer for storing an encoded scan data. */

/**@brief Struct that contains pointers to the encoded advertising data. */
static ble_gap_adv_data_t m_adv_data =
{
.adv_data =
{
  .p_data = m_enc_advdata,
  .len = BLE_GAP_ADV_SET_DATA_SIZE_MAX
},
.scan_rsp_data =
{
  .p_data = m_enc_scan_response_data,
  .len = BLE_GAP_ADV_SET_DATA_SIZE_MAX

}
};

static void advertising_init_alt(void)
{
  ret_code_t err_code;
  ble_advdata_t advdata;
  ble_advdata_t srdata;

  ble_uuid_t adv_uuids[] = {{CUSTOM_SERVICE_UUID, m_cus.uuid_type}};

  // Build and set advertising data.
  memset(&advdata, 0, sizeof(advdata));

  advdata.name_type = BLE_ADVDATA_FULL_NAME;
  advdata.include_appearance = true;
  advdata.flags = BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE;

  memset(&srdata, 0, sizeof(srdata));
  srdata.uuids_complete.uuid_cnt = sizeof(adv_uuids) / sizeof(adv_uuids[0]);
  srdata.uuids_complete.p_uuids = adv_uuids;

  err_code = ble_advdata_encode(&advdata, m_adv_data.adv_data.p_data, &m_adv_data.adv_data.len);
  APP_ERROR_CHECK(err_code);

  err_code = ble_advdata_encode(&srdata, m_adv_data.scan_rsp_data.p_data, &m_adv_data.scan_rsp_data.len);
  APP_ERROR_CHECK(err_code);

  ble_gap_adv_params_t adv_params;

  // Set advertising parameters.
  memset(&adv_params, 0, sizeof(adv_params));

  adv_params.primary_phy = BLE_GAP_PHY_1MBPS;
  adv_params.duration = APP_ADV_DURATION;
  adv_params.properties.type = BLE_GAP_ADV_TYPE_CONNECTABLE_SCANNABLE_UNDIRECTED;
  adv_params.p_peer_addr = NULL;
  adv_params.filter_policy = BLE_GAP_ADV_FP_ANY;
  adv_params.interval = APP_ADV_INTERVAL;

  err_code = sd_ble_gap_adv_set_configure(&m_adv_handle, &m_adv_data, &adv_params);
  APP_ERROR_CHECK(err_code);
}

static void advertising_start_alt(bool erase_bonds)
{
  ret_code_t err_code;

  if (erase_bonds == true)
  {
  delete_bonds();
  // Advertising is started by PM_EVT_PEERS_DELETED_SUCEEDED event
  }
  else
  { 

  err_code = sd_ble_gap_adv_start(m_adv_handle, APP_BLE_CONN_CFG_TAG);
  APP_ERROR_CHECK(err_code);
  }
}

[Keith Brafford]

I finally figured out how to add a scan response packet with the ble_advertising module, so I just moved the entire device name by itself there.  I also made the appearance field optional, so I can steal those bytes back if I need them. It was actually a lot easier than I was making it out to be earlier.

// remove the device name from the main advertising packet
//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;

init.srdata.name_type = BLE_ADVDATA_FULL_NAME;
#ifdef INCLUDE_APPEARANCE
init.srdata.include_appearance = true;
#endif

err_code = ble_advertising_init(&m_advertising, &init);