LinkLossService.h

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2006-2013 ARM Limited
00003  *
00004  * Licensed under the Apache License, Version 2.0 (the "License");
00005  * you may not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  *
00008  *     http://www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 
00017 #ifndef __BLE_LINK_LOSS_SERVICE_H__
00018 #define __BLE_LINK_LOSS_SERVICE_H__
00019 
00020 #include "ble/Gap.h"
00021 
00022 /**
00023 * @class LinkLossService
00024 * @brief This service defines behavior when a link is lost between two devices.
00025 * Service:  https://developer.bluetooth.org/gatt/services/Pages/ServiceViewer.aspx?u=org.bluetooth.service.link_loss.xml
00026 * Alertness Level Char: https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.alert_level.xml
00027 */
00028 class LinkLossService {
00029 public:
00030     enum AlertLevel_t {
00031         NO_ALERT   = 0,
00032         MILD_ALERT = 1,
00033         HIGH_ALERT = 2
00034     };
00035 
00036     typedef void (* callback_t)(AlertLevel_t level);
00037 
00038     /**
00039      * @param[ref] ble
00040      *               BLE object for the underlying controller.
00041      */
00042     LinkLossService (BLE &bleIn, callback_t callbackIn, AlertLevel_t levelIn = NO_ALERT) :
00043         ble(bleIn),
00044         alertLevel(levelIn),
00045         callback(callbackIn),
00046         alertLevelChar(GattCharacteristic::UUID_ALERT_LEVEL_CHAR, reinterpret_cast<uint8_t *>(&alertLevel)) {
00047         static bool serviceAdded = false; /* We should only ever add one LinkLoss service. */
00048         if (serviceAdded) {
00049             return;
00050         }
00051 
00052         GattCharacteristic *charTable[] = {&alertLevelChar};
00053         GattService         linkLossService(GattService::UUID_LINK_LOSS_SERVICE, charTable, sizeof(charTable) / sizeof(GattCharacteristic *));
00054 
00055         ble.gattServer().addService(linkLossService);
00056         serviceAdded = true;
00057 
00058         ble.gap().onDisconnection(this, &LinkLossService::onDisconnectionFilter);
00059         ble.gattServer().onDataWritten(this, &LinkLossService::onDataWritten);
00060     }
00061 
00062     /**
00063      * Update the callback.
00064      */
00065     void setCallback(callback_t newCallback) {
00066         callback = newCallback;
00067     }
00068 
00069     /**
00070      * Update alertness level.
00071      */
00072     void setAlertLevel(AlertLevel_t newLevel) {
00073         alertLevel = newLevel;
00074     }
00075 
00076 protected:
00077     /**
00078      * This callback allows receiving updates to the AlertLevel characteristic.
00079      *
00080      * @param[in] params
00081      *     Information about the characterisitc being updated.
00082      */
00083     virtual void onDataWritten(const GattWriteCallbackParams *params) {
00084         if (params->handle == alertLevelChar.getValueHandle()) {
00085             alertLevel = *reinterpret_cast<const AlertLevel_t *>(params->data);
00086         }
00087     }
00088 
00089     void onDisconnectionFilter(const Gap::DisconnectionCallbackParams_t *params) {
00090         if (alertLevel != NO_ALERT) {
00091             callback(alertLevel);
00092         }
00093     }
00094 
00095 protected:
00096     BLE          &ble;
00097     AlertLevel_t  alertLevel;
00098     callback_t    callback;
00099 
00100     ReadWriteGattCharacteristic<uint8_t>  alertLevelChar;
00101 };
00102 
00103 #endif /* __BLE_LINK_LOSS_SERVICE_H__ */