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 bleIn
00040      *               BLE object for the underlying controller.
00041      * @param callbackIn Callback invoked upon disconnection.
00042      * @param levelIn Alert level.
00043      */
00044     LinkLossService (BLE &bleIn, callback_t callbackIn, AlertLevel_t levelIn = NO_ALERT) :
00045         ble(bleIn),
00046         alertLevel(levelIn),
00047         callback(callbackIn),
00048         alertLevelChar(GattCharacteristic::UUID_ALERT_LEVEL_CHAR, reinterpret_cast<uint8_t *>(&alertLevel)) {
00049         static bool serviceAdded = false; /* We should only ever add one LinkLoss service. */
00050         if (serviceAdded) {
00051             return;
00052         }
00053 
00054         GattCharacteristic *charTable[] = {&alertLevelChar};
00055         GattService         linkLossService(GattService::UUID_LINK_LOSS_SERVICE, charTable, sizeof(charTable) / sizeof(GattCharacteristic *));
00056 
00057         ble.gattServer().addService(linkLossService);
00058         serviceAdded = true;
00059 
00060         ble.gap().onDisconnection(this, &LinkLossService::onDisconnectionFilter);
00061         ble.gattServer().onDataWritten(this, &LinkLossService::onDataWritten);
00062     }
00063 
00064     /**
00065      * Update the callback.
00066      */
00067     void setCallback(callback_t newCallback) {
00068         callback = newCallback;
00069     }
00070 
00071     /**
00072      * Update alertness level.
00073      */
00074     void setAlertLevel(AlertLevel_t newLevel) {
00075         alertLevel = newLevel;
00076     }
00077 
00078 protected:
00079     /**
00080      * This callback allows receiving updates to the AlertLevel characteristic.
00081      *
00082      * @param[in] params
00083      *     Information about the characteristic being updated.
00084      */
00085     virtual void onDataWritten(const GattWriteCallbackParams *params) {
00086         if (params->handle == alertLevelChar.getValueHandle()) {
00087             alertLevel = *reinterpret_cast<const AlertLevel_t *>(params->data);
00088         }
00089     }
00090 
00091     void onDisconnectionFilter(const Gap::DisconnectionCallbackParams_t *params) {
00092         if (alertLevel != NO_ALERT) {
00093             callback(alertLevel);
00094         }
00095     }
00096 
00097 protected:
00098     BLE          &ble;
00099     AlertLevel_t  alertLevel;
00100     callback_t    callback;
00101 
00102     ReadWriteGattCharacteristic<uint8_t>  alertLevelChar;
00103 };
00104 
00105 #endif /* __BLE_LINK_LOSS_SERVICE_H__ */