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HealthThermometerService.h
1 /* mbed Microcontroller Library
2  * Copyright (c) 2006-2013 ARM Limited
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef __BLE_HEALTH_THERMOMETER_SERVICE_H__
18 #define __BLE_HEALTH_THERMOMETER_SERVICE_H__
19 
20 #include "ble/BLE.h"
21 
22 #if BLE_FEATURE_GATT_SERVER
23 
24 /**
25 * @class HealthThermometerService
26 * @brief BLE Health Thermometer Service. This service provides the location of the thermometer and the temperature.
27 * Service: https://developer.bluetooth.org/gatt/profiles/Pages/ProfileViewer.aspx?u=org.bluetooth.profile.health_thermometer.xml
28 * Temperature Measurement: https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.temperature_measurement.xml
29 * Temperature Type: https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.temperature_type.xml
30 */
31 class HealthThermometerService {
32 public:
33  /**
34  * @brief Location of sensor on the body.
35  */
36  enum SensorLocation_t {
37  LOCATION_ARMPIT = 1, /*!< Armpit. */
38  LOCATION_BODY, /*!< Body. */
39  LOCATION_EAR, /*!< Ear. */
40  LOCATION_FINGER, /*!< Finger. */
41  LOCATION_GI_TRACT, /*!< GI tract */
42  LOCATION_MOUTH, /*!< Mouth. */
43  LOCATION_RECTUM, /*!< Rectum. */
44  LOCATION_TOE, /*!< Toe. */
45  LOCATION_EAR_DRUM, /*!< Eardrum. */
46  };
47 
48 public:
49  /**
50  * @brief Add the Health Thermometer Service to an existing BLE object, initialize with temperature and location.
51  * @param[in] _ble Reference to the BLE device.
52  * @param[in] initialTemp Initial value in celsius.
53  * @param[in] _location
54  */
55  HealthThermometerService(BLE &_ble, float initialTemp, uint8_t _location) :
56  ble(_ble),
57  valueBytes(initialTemp),
58  tempMeasurement(GattCharacteristic::UUID_TEMPERATURE_MEASUREMENT_CHAR, (TemperatureValueBytes *)valueBytes.getPointer(), GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_INDICATE),
59  tempLocation(GattCharacteristic::UUID_TEMPERATURE_TYPE_CHAR, &_location) {
60 
61  GattCharacteristic *hrmChars[] = {&tempMeasurement, &tempLocation, };
62  GattService hrmService(GattService::UUID_HEALTH_THERMOMETER_SERVICE, hrmChars, sizeof(hrmChars) / sizeof(GattCharacteristic *));
63 
64  ble.gattServer().addService(hrmService);
65  }
66 
67  /**
68  * @brief Update the temperature being broadcast.
69  *
70  * @param[in] temperature
71  * Floating point value of the temperature.
72  *
73  */
74  void updateTemperature(float temperature) {
75  valueBytes.updateTemperature(temperature);
76  ble.gattServer().write(tempMeasurement.getValueHandle(), valueBytes.getPointer(), sizeof(TemperatureValueBytes));
77  }
78 
79  /**
80  * @brief Update the location.
81  * @param loc
82  * New location value.
83  */
84  void updateLocation(SensorLocation_t loc) {
85  ble.gattServer().write(tempLocation.getValueHandle(), reinterpret_cast<uint8_t *>(&loc), sizeof(uint8_t));
86  }
87 
88 private:
89  /* Private internal representation for the bytes used to work with the vaulue of the temperature characteristic. */
90  struct TemperatureValueBytes {
91  static const unsigned OFFSET_OF_FLAGS = 0;
92  static const unsigned OFFSET_OF_VALUE = OFFSET_OF_FLAGS + sizeof(uint8_t);
93  static const unsigned SIZEOF_VALUE_BYTES = sizeof(uint8_t) + sizeof(float);
94 
95  static const unsigned TEMPERATURE_UNITS_FLAG_POS = 0;
96  static const unsigned TIMESTAMP_FLAG_POS = 1;
97  static const unsigned TEMPERATURE_TYPE_FLAG_POS = 2;
98 
99  static const uint8_t TEMPERATURE_UNITS_CELSIUS = 0;
100  static const uint8_t TEMPERATURE_UNITS_FAHRENHEIT = 1;
101 
102  TemperatureValueBytes(float initialTemperature) : bytes() {
103  /* Assumption: temperature values are expressed in celsius */
104  bytes[OFFSET_OF_FLAGS] = (TEMPERATURE_UNITS_CELSIUS << TEMPERATURE_UNITS_FLAG_POS) |
105  (false << TIMESTAMP_FLAG_POS) |
106  (false << TEMPERATURE_TYPE_FLAG_POS);
107  updateTemperature(initialTemperature);
108  }
109 
110  void updateTemperature(float temp) {
111  uint32_t temp_ieee11073 = quick_ieee11073_from_float(temp);
112  memcpy(&bytes[OFFSET_OF_VALUE], &temp_ieee11073, sizeof(float));
113  }
114 
115  uint8_t *getPointer(void) {
116  return bytes;
117  }
118 
119  const uint8_t *getPointer(void) const {
120  return bytes;
121  }
122 
123 private:
124  /**
125  * @brief A very quick conversion between a float temperature and 11073-20601 FLOAT-Type.
126  * @param temperature The temperature as a float.
127  * @return The temperature in 11073-20601 FLOAT-Type format.
128  */
129  uint32_t quick_ieee11073_from_float(float temperature) {
130  uint8_t exponent = 0xFE; //Exponent is -2
131  uint32_t mantissa = (uint32_t)(temperature * 100);
132 
133  return (((uint32_t)exponent) << 24) | mantissa;
134  }
135 
136 private:
137  /* First byte: 8-bit flags. Second field is a float holding the temperature value. */
138  /* See https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.temperature_measurement.xml */
139  uint8_t bytes[SIZEOF_VALUE_BYTES];
140  };
141 
142 protected:
143  BLE &ble;
144  TemperatureValueBytes valueBytes;
145  ReadOnlyGattCharacteristic<TemperatureValueBytes> tempMeasurement;
146  ReadOnlyGattCharacteristic<uint8_t> tempLocation;
147 };
148 
149 #endif // BLE_FEATURE_GATT_SERVER
150 
151 #endif /* #ifndef __BLE_HEALTH_THERMOMETER_SERVICE_H__*/
HealthThermometerService::updateTemperature
void updateTemperature(float temperature)
Update the temperature being broadcast.
Definition: HealthThermometerService.h:74
GattService::UUID_HEALTH_THERMOMETER_SERVICE
UUID of the health thermometer.
Definition: GattService.h:84
BLE
Abstract away BLE-capable radio transceivers or SOCs.
Definition: BLE.h:139
HealthThermometerService::SensorLocation_t
SensorLocation_t
Location of sensor on the body.
Definition: HealthThermometerService.h:36
HealthThermometerService
BLE Health Thermometer Service.
Definition: HealthThermometerService.h:31
GattCharacteristic
Representation of a GattServer characteristic.
Definition: GattCharacteristic.h:94
GattCharacteristic::getValueHandle
GattAttribute::Handle_t getValueHandle(void) const
Get the characteristic&#39;s value attribute handle in the ATT table.
Definition: GattCharacteristic.h:1715
HealthThermometerService::updateLocation
void updateLocation(SensorLocation_t loc)
Update the location.
Definition: HealthThermometerService.h:84
GattService
Representation of a GattServer service.
Definition: GattService.h:38
ble
Entry namespace for all BLE API definitions.
HealthThermometerService::HealthThermometerService
HealthThermometerService(BLE &_ble, float initialTemp, uint8_t _location)
Add the Health Thermometer Service to an existing BLE object, initialize with temperature and locatio...
Definition: HealthThermometerService.h:55
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