Reading the central device name (smart phone) in nRF52DK(Peripheral) and printing on the terminal

RE: Reading the central device name (smart phone) in nRF52DK(Peripheral) and printing on the terminal

skulkarni — Thu, 18 Jul 2019 10:16:31 GMT

Thank you Vidar for the detailed explanation. Now I am am able to read the device name.

RE: Reading the central device name (smart phone) in nRF52DK(Peripheral) and printing on the terminal

Vidar Berg — Thu, 18 Jul 2019 07:38:35 GMT

Hi,

sd_ble_gatts_attr_get will only return information about local attributes. You have to use GATT client read procedure to get the device name from your connected phone, see GATTC Characteristic or Descriptor Value Read. But before you attempt to a GATT read you need to do a service discovery to find the attribute handles of the characteristics you want to access. You can use the database discovery module for this.

Below is a code snippet showing how you can configure the discovery module to search for the device name characteristic. Please refer to the GAP central examples in the SDK if you run into problems with adding the module to your project.

/**@brief Function for handling database discovery events.
 *
 * @details This function is a callback function to handle events from the database discovery module.
 *          Depending on the UUIDs that are discovered, this function forwards the events
 *          to their respective services.
 *
 * @param[in] p_event  Pointer to the database discovery event.
 */
static void db_disc_handler(ble_db_discovery_evt_t * p_evt)
{
    
    uint32_t err_code; 
    uint16_t att_handle;

    ble_gatt_db_char_t * p_chars = p_evt->params.discovered_db.charateristics;
    
    if (    (p_evt->evt_type == BLE_DB_DISCOVERY_COMPLETE)
        &&  (p_evt->params.discovered_db.srv_uuid.uuid == BLE_UUID_GAP)
        &&  (p_evt->params.discovered_db.srv_uuid.type == BLE_UUID_TYPE_BLE))
    {
        for (uint32_t i = 0; i < p_evt->params.discovered_db.char_count; i++)
        {
              if (p_chars[i].characteristic.uuid.uuid == BLE_UUID_GAP_CHARACTERISTIC_DEVICE_NAME)
              {
                  att_handle = p_chars[i].characteristic.handle_value;
                  /*Found Device name characteristic - Start read procedure*/
                  err_code = sd_ble_gattc_read(p_evt->conn_handle, att_handle, 0);
                  APP_ERROR_CHECK(err_code);
              }
        }
    }
    
}


/** @brief Function for initializing the database discovery module. */
static void db_discovery_init(void)
{
    static ble_uuid_t ble_uuid;

    ble_uuid.type = BLE_UUID_TYPE_BLE;
    ble_uuid.uuid = BLE_UUID_GAP;
    
    ret_code_t err_code = ble_db_discovery_init(db_disc_handler);
    APP_ERROR_CHECK(err_code);

    err_code = ble_db_discovery_evt_register(&ble_uuid);
    APP_ERROR_CHECK(err_code);
}

RE: Reading the central device name (smart phone) in nRF52DK(Peripheral) and printing on the terminal

skulkarni — Thu, 18 Jul 2019 04:01:33 GMT

Tried to get the device name using sd_ble_gatts_attr_get but it doent work.

static void on_ble_evt(ble_evt_t * p_ble_evt)
{
  case BLE_GAP_EVT_CONNECTED:
  m_conn_handle = p_ble_evt->evt.gap_evt.conn_handle;
  ble_uuid_t temp;
  temp.type = BLE_UUID_TYPE_BLE;
  temp.uuid = BLE_UUID_GAP_CHARACTERISTIC_DEVICE_NAME;
  err_code = sd_ble_gatts_attr_get(m_conn_handle, &temp, NULL);
  APP_ERROR_CHECK(err_code); // Fails here

RE: Reading the central device name (smart phone) in nRF52DK(Peripheral) and printing on the terminal

skulkarni — Tue, 16 Jul 2019 09:32:56 GMT

Yes. Just came to know that device name is part of the GATT primary service. I am looking for reading this attribute on connection.

RE: Reading the central device name (smart phone) in nRF52DK(Peripheral) and printing on the terminal

awneil — Tue, 16 Jul 2019 07:53:08 GMT

But isn't that name just for when other things are trying to connect to your phone - ie, when the phone is a "peripheral" ?

RE: Reading the central device name (smart phone) in nRF52DK(Peripheral) and printing on the terminal

skulkarni — Tue, 16 Jul 2019 07:44:18 GMT

nRF52 is programmed as peripheral. I have not set any name so by default it get recognized as "nrf " in my smart phone. My smart phone Bluetooth device name is "skulkarni" . When I try to pair (from Smart phone), I want to read central device name(skulkarni) in the peripheral. For some reasons i need to know the central device name.

RE: Reading the central device name (smart phone) in nRF52DK(Peripheral) and printing on the terminal

awneil — Tue, 16 Jul 2019 07:32:03 GMT

What "name" are you thinking of?