Mbed OS Reference | LinkLossService.h Source File

 /* mbed Microcontroller Library
  * Copyright (c) 2006-2020 ARM Limited
  *
  * SPDX-License-Identifier: Apache-2.0
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 
 #ifndef __BLE_LINK_LOSS_SERVICE_H__
 #define __BLE_LINK_LOSS_SERVICE_H__
 
 #include "ble/BLE.h"
 #include "ble/Gap.h"
 #include "ble/GattServer.h"
 
 #if BLE_FEATURE_GATT_SERVER
 
 /**
 * @class LinkLossService
 * @brief This service defines behavior when a link is lost between two devices.
 * Service:  https://developer.bluetooth.org/gatt/services/Pages/ServiceViewer.aspx?u=org.bluetooth.service.link_loss.xml
 * Alertness Level Char: https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.alert_level.xml
 */
 class LinkLossService : public ble::Gap::EventHandler
 {
 public:
     enum AlertLevel_t {
         NO_ALERT   = 0,
         MILD_ALERT = 1,
         HIGH_ALERT = 2
     };
 
     typedef void (* callback_t)(AlertLevel_t level);
 
     /**
      * @param bleIn
      *               BLE object for the underlying controller.
      * @param callbackIn Callback invoked upon disconnection.
      * @param levelIn Alert level.
      */
     LinkLossService(BLE &bleIn, callback_t callbackIn, AlertLevel_t levelIn = NO_ALERT) :
         ble(bleIn),
         alertLevel(levelIn),
         callback(callbackIn),
         alertLevelChar(GattCharacteristic::UUID_ALERT_LEVEL_CHAR, reinterpret_cast<uint8_t *>(&alertLevel)) {
         static bool serviceAdded = false; /* We should only ever add one LinkLoss service. */
         if (serviceAdded) {
             return;
         }
 
         GattCharacteristic *charTable[] = {&alertLevelChar};
         GattService         linkLossService(GattService::UUID_LINK_LOSS_SERVICE, charTable, sizeof(charTable) / sizeof(charTable[0]));
 
         ble.gattServer().addService(linkLossService);
         serviceAdded = true;
 
         ble.gap().setEventHandler(this);
         ble.gattServer().onDataWritten(this, &LinkLossService::onDataWritten);
     }
 
     /**
      * Update the callback.
      */
     void setCallback(callback_t newCallback) {
         callback = newCallback;
     }
 
     /**
      * Update alertness level.
      */
     void setAlertLevel(AlertLevel_t newLevel) {
         alertLevel = newLevel;
     }
 
 protected:
     /**
      * This callback allows receiving updates to the AlertLevel characteristic.
      *
      * @param[in] params
      *     Information about the characteristic being updated.
      */
     virtual void onDataWritten(const GattWriteCallbackParams *params) {
         if (params->handle == alertLevelChar.getValueHandle()) {
             alertLevel = *reinterpret_cast<const AlertLevel_t *>(params->data);
         }
     }
 
     void onDisconnectionComplete(const ble::DisconnectionCompleteEvent &) override {
         if (alertLevel != NO_ALERT) {
             callback(alertLevel);
         }
     }
 
 protected:
     BLE          &ble;
     AlertLevel_t  alertLevel;
     callback_t    callback;
 
     ReadWriteGattCharacteristic<uint8_t> alertLevelChar;
 };
 
 #endif // BLE_FEATURE_GATT_SERVER
 
 #endif /* __BLE_LINK_LOSS_SERVICE_H__ */
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