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LinkLossService.h
1 /* mbed Microcontroller Library
2  * Copyright (c) 2006-2020 ARM Limited
3  *
4  * SPDX-License-Identifier: Apache-2.0
5  *
6  * Licensed under the Apache License, Version 2.0 (the "License");
7  * you may not use this file except in compliance with the License.
8  * You may obtain a copy of the License at
9  *
10  * http://www.apache.org/licenses/LICENSE-2.0
11  *
12  * Unless required by applicable law or agreed to in writing, software
13  * distributed under the License is distributed on an "AS IS" BASIS,
14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15  * See the License for the specific language governing permissions and
16  * limitations under the License.
17  */
18 
19 #ifndef __BLE_LINK_LOSS_SERVICE_H__
20 #define __BLE_LINK_LOSS_SERVICE_H__
21 
22 #include "ble/BLE.h"
23 #include "ble/Gap.h"
24 #include "ble/GattServer.h"
25 
26 #if BLE_FEATURE_GATT_SERVER
27 
28 /**
29 * @class LinkLossService
30 * @brief This service defines behavior when a link is lost between two devices.
31 * Service: https://developer.bluetooth.org/gatt/services/Pages/ServiceViewer.aspx?u=org.bluetooth.service.link_loss.xml
32 * Alertness Level Char: https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.alert_level.xml
33 */
35 {
36 public:
37  enum AlertLevel_t {
38  NO_ALERT = 0,
39  MILD_ALERT = 1,
40  HIGH_ALERT = 2
41  };
42 
43  typedef void (* callback_t)(AlertLevel_t level);
44 
45  /**
46  * @param bleIn
47  * BLE object for the underlying controller.
48  * @param callbackIn Callback invoked upon disconnection.
49  * @param levelIn Alert level.
50  */
51  LinkLossService(BLE &bleIn, callback_t callbackIn, AlertLevel_t levelIn = NO_ALERT) :
52  ble(bleIn),
53  alertLevel(levelIn),
54  callback(callbackIn),
55  alertLevelChar(GattCharacteristic::UUID_ALERT_LEVEL_CHAR, reinterpret_cast<uint8_t *>(&alertLevel)) {
56  static bool serviceAdded = false; /* We should only ever add one LinkLoss service. */
57  if (serviceAdded) {
58  return;
59  }
60 
61  GattCharacteristic *charTable[] = {&alertLevelChar};
62  GattService linkLossService(GattService::UUID_LINK_LOSS_SERVICE, charTable, sizeof(charTable) / sizeof(charTable[0]));
63 
64  ble.gattServer().addService(linkLossService);
65  serviceAdded = true;
66 
67  ble.gap().setEventHandler(this);
68  ble.gattServer().onDataWritten(this, &LinkLossService::onDataWritten);
69  }
70 
71  /**
72  * Update the callback.
73  */
74  void setCallback(callback_t newCallback) {
75  callback = newCallback;
76  }
77 
78  /**
79  * Update alertness level.
80  */
81  void setAlertLevel(AlertLevel_t newLevel) {
82  alertLevel = newLevel;
83  }
84 
85 protected:
86  /**
87  * This callback allows receiving updates to the AlertLevel characteristic.
88  *
89  * @param[in] params
90  * Information about the characteristic being updated.
91  */
92  virtual void onDataWritten(const GattWriteCallbackParams *params) {
93  if (params->handle == alertLevelChar.getValueHandle()) {
94  alertLevel = *reinterpret_cast<const AlertLevel_t *>(params->data);
95  }
96  }
97 
99  if (alertLevel != NO_ALERT) {
100  callback(alertLevel);
101  }
102  }
103 
104 protected:
105  BLE &ble;
106  AlertLevel_t alertLevel;
107  callback_t callback;
108 
110 };
111 
112 #endif // BLE_FEATURE_GATT_SERVER
113 
114 #endif /* __BLE_LINK_LOSS_SERVICE_H__ */
const uint8_t * data
Pointer to the data to write.
UUID of the Link Loss service.
GattAttribute::Handle_t getValueHandle() const
Get the characteristic&#39;s value attribute handle in the ATT table.
GATT Write event definition.
Representation of a GattServer characteristic.
Event produced when a disconnection is complete.
Definition: Events.h:639
Definition of the general handler of Gap related events.
Definition: Gap.h:303
GattAttribute::Handle_t handle
Handle of the attribute to which the write operation applies.
Representation of a GattServer service.
Entry namespace for all BLE API definitions.
Abstract away BLE-capable radio transceivers or SOCs.
Definition: BLE.h:137
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