HealthThermometerService.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_HEALTH_THERMOMETER_SERVICE_H__
00018 #define __BLE_HEALTH_THERMOMETER_SERVICE_H__
00019 
00020 #include "BLEDevice.h"
00021 
00022 /* Health Thermometer Service */
00023 /* Service:  https://developer.bluetooth.org/gatt/profiles/Pages/ProfileViewer.aspx?u=org.bluetooth.profile.health_thermometer.xml */
00024 /* Temperature Measurement: https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.temperature_measurement.xml */
00025 /* Temperature Type: https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.temperature_type.xml */
00026 class HealthThermometerService {
00027 public:
00028     enum {
00029         LOCATION_ARMPIT = 1,
00030         LOCATION_BODY,
00031         LOCATION_EAR,
00032         LOCATION_FINGER,
00033         LOCATION_GI_TRACT,
00034         LOCATION_MOUTH,
00035         LOCATION_RECTUM,
00036         LOCATION_TOE,
00037         LOCATION_EAR_DRUM,
00038     };
00039 
00040 public:
00041 
00042     /**
00043      * @param[in] _ble         reference to the BLE device
00044      * @param[in] initialTemp  initial value in celsius
00045      * @param[in] _location
00046      */
00047     HealthThermometerService(BLEDevice &_ble, float initialTemp, uint8_t _location) :
00048         ble(_ble),
00049         valueBytes(initialTemp),
00050         tempMeasurement(GattCharacteristic::UUID_TEMPERATURE_MEASUREMENT_CHAR, valueBytes.getPointer(),
00051                         sizeof(TemperatureValueBytes), sizeof(TemperatureValueBytes),
00052                         GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_READ | GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_NOTIFY),
00053         tempLocation(GattCharacteristic::UUID_TEMPERATURE_TYPE_CHAR, (uint8_t *)&_location, sizeof(_location), sizeof(_location),
00054                      GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_READ) {
00055 
00056         GattCharacteristic *hrmChars[] = {&tempMeasurement, &tempLocation, };
00057         GattService         hrmService(GattService::UUID_HEALTH_THERMOMETER_SERVICE, hrmChars, sizeof(hrmChars) / sizeof(GattCharacteristic *));
00058 
00059         ble.addService(hrmService);
00060     }
00061 
00062     void updateTemperature(float temperature) {
00063         if (ble.getGapState().connected) {
00064             valueBytes.updateTemperature(temperature);
00065             ble.updateCharacteristicValue (tempMeasurement.getValueAttribute().getHandle(), valueBytes.getPointer(), sizeof(TemperatureValueBytes));
00066         }
00067     }
00068 
00069 private:
00070     /* Private internal representation for the bytes used to work with the vaulue of the heart-rate characteristic. */
00071     struct TemperatureValueBytes {
00072         static const unsigned OFFSET_OF_FLAGS    = 0;
00073         static const unsigned OFFSET_OF_VALUE    = OFFSET_OF_FLAGS + sizeof(uint8_t);
00074         static const unsigned SIZEOF_VALUE_BYTES = sizeof(uint8_t) + sizeof(float);
00075 
00076         static const unsigned TEMPERATURE_UNITS_FLAG_POS = 0;
00077         static const unsigned TIMESTAMP_FLAG_POS         = 1;
00078         static const unsigned TEMPERATURE_TYPE_FLAG_POS  = 2;
00079 
00080         static const uint8_t TEMPERATURE_UNITS_CELSIUS    = 0;
00081         static const uint8_t TEMPERATURE_UNITS_FAHRENHEIT = 1;
00082 
00083         TemperatureValueBytes(float initialTemperature) : bytes() {
00084             /* assumption: temperature values are expressed in Celsius */
00085             bytes[OFFSET_OF_FLAGS] =  (TEMPERATURE_UNITS_CELSIUS << TEMPERATURE_UNITS_FLAG_POS) |
00086                                       (false << TIMESTAMP_FLAG_POS) |
00087                                       (false << TEMPERATURE_TYPE_FLAG_POS);
00088             updateTemperature(initialTemperature);
00089         }
00090 
00091         void updateTemperature(float temp) {
00092             uint32_t temp_ieee11073 = quick_ieee11073_from_float(temp);
00093             memcpy(&bytes[OFFSET_OF_VALUE], &temp_ieee11073, sizeof(float));
00094         }
00095 
00096         uint8_t *getPointer(void) {
00097             return bytes;
00098         }
00099 
00100         const uint8_t *getPointer(void) const {
00101             return bytes;
00102         }
00103 
00104     private:
00105         /**
00106          * @brief A very quick conversion between a float temperature and 11073-20601 FLOAT-Type.
00107          * @param temperature The temperature as a float.
00108          * @return The temperature in 11073-20601 FLOAT-Type format.
00109          */
00110         uint32_t quick_ieee11073_from_float(float temperature) {
00111             uint8_t  exponent = 0xFE; //exponent is -2
00112             uint32_t mantissa = (uint32_t)(temperature * 100);
00113 
00114             return (((uint32_t)exponent) << 24) | mantissa;
00115         }
00116 
00117 
00118     private:
00119         /* First byte = 8-bit flags, Second field is a float holding the temperature value. */
00120         /* See --> https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.temperature_measurement.xml */
00121         uint8_t bytes[SIZEOF_VALUE_BYTES];
00122     };
00123 
00124 private:
00125     BLEDevice             &ble;
00126     TemperatureValueBytes  valueBytes;
00127     GattCharacteristic     tempMeasurement;
00128     GattCharacteristic     tempLocation;
00129 };
00130 
00131 #endif /* #ifndef __BLE_HEALTH_THERMOMETER_SERVICE_H__*/