GETTING NOTIFICATION ON SAME CHARACTERISTIC [ LED handler]

[sowmiya]

Hello ,

NRF52840 

sdk 15.2

 In my application using ble central example in nrf52840 , i am able to write data in led characteristics and getting notification on HVX using Button cccd handle and now i m trying to get notification data on led handle instead of button handle , is this possible to get notification on led handle from peripheral to central ?i have changed to led characteristics as below 

  

static void on_hvx(ble_lbs_c_t * p_ble_lbs_c, ble_evt_t const * p_ble_evt)
{
    // Check if the event is on the link for this instance
    if (p_ble_lbs_c->conn_handle != p_ble_evt->evt.gattc_evt.conn_handle)
    {
        return;
    }
    // Check if this is a Button notification.
  //  if (p_ble_evt->evt.gattc_evt.params.hvx.handle == p_ble_lbs_c->peer_lbs_db.button_handle)
   (p_ble_evt->evt.gattc_evt.params.hvx.handle == p_ble_lbs_c->peer_lbs_db.led_handle)
    {
//        if (p_ble_evt->evt.gattc_evt.params.hvx.len == 1)
//        {
            ble_lbs_c_evt_t ble_lbs_c_evt;

            ble_lbs_c_evt.evt_type                   = BLE_LBS_C_EVT_DISCOVERY_COMPLETE;
            ble_lbs_c_evt.conn_handle                = p_ble_lbs_c->conn_handle;
            ble_lbs_c_evt.params.button.button_state = p_ble_evt->evt.gattc_evt.params.hvx.data[0];
//            p_ble_lbs_c->evt_handler(p_ble_lbs_c, &ble_lbs_c_evt);
//        }
    }
}


/**@brief Function for handling Disconnected event received from the SoftDevice.
 *
 * @details This function check if the disconnect event is happening on the link
 *          associated with the current instance of the module, if so it will set its
 *          conn_handle to invalid.
 *
 * @param[in] p_ble_lbs_c Pointer to the Led Button Client structure.
 * @param[in] p_ble_evt   Pointer to the BLE event received.
 */
static void on_disconnected(ble_lbs_c_t * p_ble_lbs_c, ble_evt_t const * p_ble_evt)
{
    if (p_ble_lbs_c->conn_handle == p_ble_evt->evt.gap_evt.conn_handle)
    {
        p_ble_lbs_c->conn_handle                    = BLE_CONN_HANDLE_INVALID;
        p_ble_lbs_c->peer_lbs_db.button_cccd_handle = BLE_GATT_HANDLE_INVALID;
        p_ble_lbs_c->peer_lbs_db.button_handle      = BLE_GATT_HANDLE_INVALID;
        p_ble_lbs_c->peer_lbs_db.led_handle         = BLE_GATT_HANDLE_INVALID;
    }
}


void ble_lbs_on_db_disc_evt(ble_lbs_c_t * p_ble_lbs_c, ble_db_discovery_evt_t const * p_evt)
{
    // Check if the Led Button Service was discovered.
    if (p_evt->evt_type == BLE_DB_DISCOVERY_COMPLETE &&
        p_evt->params.discovered_db.srv_uuid.uuid == LBS_UUID_SERVICE &&
        p_evt->params.discovered_db.srv_uuid.type == p_ble_lbs_c->uuid_type)
    {
        ble_lbs_c_evt_t evt;

        evt.evt_type    = BLE_LBS_C_EVT_DISCOVERY_COMPLETE;
        evt.conn_handle = p_evt->conn_handle;

        for (uint32_t i = 0; i < p_evt->params.discovered_db.char_count; i++)
        {
            const ble_gatt_db_char_t * p_char = &(p_evt->params.discovered_db.charateristics[i]);
            switch (p_char->characteristic.uuid.uuid)
            {
                case LBS_UUID_LED_CHAR:
                    evt.params.peer_db.led_handle = p_char->characteristic.handle_value;
                    break;
                case LBS_UUID_BUTTON_CHAR:
                    evt.params.peer_db.button_handle      = p_char->characteristic.handle_value;
                    evt.params.peer_db.button_cccd_handle = p_char->cccd_handle;
                    break;

                default:
                    break;
            }
        }

        NRF_LOG_DEBUG("Led Button Service discovered at peer.");
        //If the instance has been assigned prior to db_discovery, assign the db_handles
        if (p_ble_lbs_c->conn_handle != BLE_CONN_HANDLE_INVALID)
        {
            if ((p_ble_lbs_c->peer_lbs_db.led_handle         == BLE_GATT_HANDLE_INVALID)&&
                (p_ble_lbs_c->peer_lbs_db.button_handle      == BLE_GATT_HANDLE_INVALID)&&
                (p_ble_lbs_c->peer_lbs_db.button_cccd_handle == BLE_GATT_HANDLE_INVALID))
            {
                p_ble_lbs_c->peer_lbs_db = evt.params.peer_db;
            }
        }

        p_ble_lbs_c->evt_handler(p_ble_lbs_c, &evt);

    }
}


uint32_t ble_lbs_c_init(ble_lbs_c_t * p_ble_lbs_c, ble_lbs_c_init_t * p_ble_lbs_c_init)
{
    uint32_t      err_code;
    ble_uuid_t    lbs_uuid;
    ble_uuid128_t lbs_base_uuid = {LBS_UUID_BASE};

    VERIFY_PARAM_NOT_NULL(p_ble_lbs_c);
    VERIFY_PARAM_NOT_NULL(p_ble_lbs_c_init);
    VERIFY_PARAM_NOT_NULL(p_ble_lbs_c_init->evt_handler);

    p_ble_lbs_c->peer_lbs_db.button_cccd_handle = BLE_GATT_HANDLE_INVALID;
    p_ble_lbs_c->peer_lbs_db.button_handle      = BLE_GATT_HANDLE_INVALID;
    p_ble_lbs_c->peer_lbs_db.led_handle         = BLE_GATT_HANDLE_INVALID;
    p_ble_lbs_c->conn_handle                    = BLE_CONN_HANDLE_INVALID;
    p_ble_lbs_c->evt_handler                    = p_ble_lbs_c_init->evt_handler;

    err_code = sd_ble_uuid_vs_add(&lbs_base_uuid, &p_ble_lbs_c->uuid_type);
    if (err_code != NRF_SUCCESS)
    {
        return err_code;
    }
    VERIFY_SUCCESS(err_code);

    lbs_uuid.type = p_ble_lbs_c->uuid_type;
    lbs_uuid.uuid = LBS_UUID_SERVICE;

    return ble_db_discovery_evt_register(&lbs_uuid);
}

void ble_lbs_c_on_ble_evt(ble_evt_t const * p_ble_evt, void * p_context)
{
    if ((p_context == NULL) || (p_ble_evt == NULL))
    {
        return;
    }

    ble_lbs_c_t * p_ble_lbs_c = (ble_lbs_c_t *)p_context;
    switch (p_ble_evt->header.evt_id)
    {
        case BLE_GATTC_EVT_HVX:
            on_hvx(p_ble_lbs_c, p_ble_evt);
            break;

        case BLE_GATTC_EVT_WRITE_RSP:
//            NRF_LOG_INFO("Write resp");
            on_write_rsp(p_ble_lbs_c, p_ble_evt);
            break;

        case BLE_GAP_EVT_DISCONNECTED:
            on_disconnected(p_ble_lbs_c, p_ble_evt);
            break;

        default:
            break;
    }
}


/**@brief Function for configuring the CCCD.
 *
 * @param[in] conn_handle The connection handle on which to configure the CCCD.
 * @param[in] handle_cccd The handle of the CCCD to be configured.
 * @param[in] enable      Whether to enable or disable the CCCD.
 *
 * @return NRF_SUCCESS if the CCCD configure was successfully sent to the peer.
 */
static uint32_t cccd_configure(uint16_t conn_handle, uint16_t handle_cccd, bool enable)
{
//    NRF_LOG_INFO("Configuring CCCD. CCCD Handle = %d, Connection Handle = %d",
//        handle_cccd,conn_handle);

    tx_message_t * p_msg;
    uint16_t       cccd_val = enable ? BLE_GATT_HVX_NOTIFICATION : 0;

    p_msg              = &m_tx_buffer[m_tx_insert_index++];
    m_tx_insert_index &= TX_BUFFER_MASK;

    p_msg->req.write_req.gattc_params.handle   = handle_cccd;
    p_msg->req.write_req.gattc_params.len      = WRITE_MESSAGE_LENGTH;
    p_msg->req.write_req.gattc_params.p_value  = p_msg->req.write_req.gattc_value;
    p_msg->req.write_req.gattc_params.offset   = 0;
    p_msg->req.write_req.gattc_params.write_op = BLE_GATT_OP_WRITE_REQ;
    p_msg->req.write_req.gattc_value[0]        = LSB_16(cccd_val);
    p_msg->req.write_req.gattc_value[1]        = MSB_16(cccd_val);
    p_msg->conn_handle                         = conn_handle;
    p_msg->type                                = WRITE_REQ;

    tx_buffer_process();
    return NRF_SUCCESS;
}


uint32_t ble_lbs_c_button_notif_enable(ble_lbs_c_t * p_ble_lbs_c)
{
    VERIFY_PARAM_NOT_NULL(p_ble_lbs_c);

    if (p_ble_lbs_c->conn_handle == BLE_CONN_HANDLE_INVALID)
    {
        printf("invalid");
        return NRF_ERROR_INVALID_STATE;
    }

    return cccd_configure(p_ble_lbs_c->conn_handle,
                         //p_ble_lbs_c->peer_lbs_db.button_cccd_handle,
                         // p_ble_lbs_c->peer_lbs_db.led_handle,
                          true);
   // return NRF_SUCCESS;
}

Thanks,

[Hung Bui]

Hi Sowmiya, 

Please show what exactly you modified to enable notification on the LED characteristic. We can't look into you full code to find what you modified. 

As far as I know you just need to enable notification when you declare the characteristic in ble_lbs_init() , so if you have    add_char_params.char_props.notify = 1; in the characteristic you add, it will be able to send notification. 

After that when you call the sd_ble_gatts_hvx() function, you need to set the handle to the handle of the LED characteristic instead of the button characteristic.