HeartRateService.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_HEART_RATE_SERVICE_H__
00018 #define __BLE_HEART_RATE_SERVICE_H__
00019 
00020 #include "BLEDevice.h"
00021 
00022 /**
00023 * @class HeartRateService
00024 * @brief BLE Service for HeartRate. This BLE Service contains the location of the sensor, the heartrate in beats per minute. <br>
00025 * Service:  https://developer.bluetooth.org/gatt/services/Pages/ServiceViewer.aspx?u=org.bluetooth.service.heart_rate.xml <br>
00026 * HRM Char: https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.heart_rate_measurement.xml <br>
00027 * Location: https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.body_sensor_location.xml
00028 */
00029 class HeartRateService {
00030 public:
00031     /**
00032     * @enum SensorLocation
00033     * @brief Location of HeartRate sensor on body.
00034     */
00035     enum {
00036         LOCATION_OTHER  = 0, /*!< Other Location */
00037         LOCATION_CHEST ,     /*!< Chest */
00038         LOCATION_WRIST ,     /*!< Wrist */
00039         LOCATION_FINGER ,    /*!< Finger */
00040         LOCATION_HAND ,      /*!< Hand */
00041         LOCATION_EAR_LOBE ,  /*!< Earlobe */
00042         LOCATION_FOOT ,      /*!< Foot */
00043     };
00044 
00045 public:
00046     /**
00047      * @brief Constructor with 8bit HRM Counter value.
00048      *
00049      * @param[ref] _ble
00050      *               Reference to the underlying BLEDevice.
00051      * @param[in] hrmCounter (8-bit)
00052      *               initial value for the hrm counter.
00053      * @param[in] location
00054      *               Sensor's location.
00055      */
00056     HeartRateService(BLEDevice &_ble, uint8_t hrmCounter, uint8_t location) :
00057         ble(_ble),
00058         valueBytes(hrmCounter),
00059         hrmRate(GattCharacteristic::UUID_HEART_RATE_MEASUREMENT_CHAR, valueBytes.getPointer(),
00060                 valueBytes.getNumValueBytes(), HeartRateValueBytes::MAX_VALUE_BYTES,
00061                 GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_NOTIFY),
00062         hrmLocation(GattCharacteristic::UUID_BODY_SENSOR_LOCATION_CHAR, (uint8_t *)&location, sizeof(location), sizeof(location),
00063                     GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_READ),
00064         controlPoint(GattCharacteristic::UUID_HEART_RATE_CONTROL_POINT_CHAR, (uint8_t *)&controlPointValue,
00065                      sizeof(controlPointValue), sizeof(controlPointValue), GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_WRITE) {
00066         setupService();
00067     }
00068 
00069     /**
00070      * @brief Constructor with a 16-bit HRM Counter value.
00071      *
00072      * @param[in] _ble
00073      *               Reference to the underlying BLEDevice.
00074      * @param[in] hrmCounter (8-bit)
00075      *               initial value for the hrm counter.
00076      * @param[in] location
00077      *               Sensor's location.
00078      */
00079     HeartRateService(BLEDevice &_ble, uint16_t hrmCounter, uint8_t location) :
00080         ble(_ble),
00081         valueBytes(hrmCounter),
00082         hrmRate(GattCharacteristic::UUID_HEART_RATE_MEASUREMENT_CHAR, valueBytes.getPointer(),
00083                 valueBytes.getNumValueBytes(), HeartRateValueBytes::MAX_VALUE_BYTES,
00084                 GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_NOTIFY),
00085         hrmLocation(GattCharacteristic::UUID_BODY_SENSOR_LOCATION_CHAR, (uint8_t *)&location, sizeof(location), sizeof(location),
00086                     GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_READ),
00087         controlPoint(GattCharacteristic::UUID_HEART_RATE_CONTROL_POINT_CHAR, (uint8_t *)&controlPointValue,
00088                      sizeof(controlPointValue), sizeof(controlPointValue), GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_WRITE) {
00089         setupService();
00090     }
00091 
00092     /**
00093      * @brief Set a new 8-bit value for heart rate.
00094      *
00095      * @param[in] hrmCounter
00096      *                  HeartRate in bpm.
00097      */
00098     void updateHeartRate(uint8_t hrmCounter) {
00099         valueBytes.updateHeartRate(hrmCounter);
00100         ble.updateCharacteristicValue (hrmRate.getValueAttribute().getHandle(), valueBytes.getPointer(), valueBytes.getNumValueBytes());
00101     }
00102 
00103     /**
00104      * Set a new 16-bit value for heart rate.
00105      *
00106      * @param[in] hrmCounter
00107      *                  HeartRate in bpm.
00108      */
00109     void updateHeartRate(uint16_t hrmCounter) {
00110         valueBytes.updateHeartRate(hrmCounter);
00111         ble.updateCharacteristicValue (hrmRate.getValueAttribute().getHandle(), valueBytes.getPointer(), valueBytes.getNumValueBytes());
00112     }
00113 
00114     /**
00115      * This callback allows the HeartRateService to receive updates to the
00116      * controlPoint Characteristic.
00117      *
00118      * @param[in] params
00119      *     Information about the characterisitc being updated.
00120      */
00121     virtual void onDataWritten(const GattCharacteristicWriteCBParams *params) {
00122         if (params->charHandle == controlPoint.getValueAttribute().getHandle()) {
00123             /* Do something here if the new value is 1; else you can override this method by
00124              * extending this class.
00125              * @NOTE: if you are extending this class, be sure to also call
00126              * ble.onDataWritten(this, &ExtendedHRService::onDataWritten); in
00127              * your constructor.
00128              */
00129         }
00130     }
00131 
00132 private:
00133     void setupService(void) {
00134         static bool serviceAdded = false; /* We should only ever need to add the heart rate service once. */
00135         if (serviceAdded) {
00136             return;
00137         }
00138 
00139         GattCharacteristic *charTable[] = {&hrmRate, &hrmLocation, &controlPoint};
00140         GattService         hrmService(GattService::UUID_HEART_RATE_SERVICE, charTable, sizeof(charTable) / sizeof(GattCharacteristic *));
00141 
00142         ble.addService(hrmService);
00143         serviceAdded = true;
00144 
00145         ble.onDataWritten(this, &HeartRateService::onDataWritten);
00146     }
00147 
00148 private:
00149     /* Private internal representation for the bytes used to work with the vaulue of the heart-rate characteristic. */
00150     struct HeartRateValueBytes {
00151         static const unsigned MAX_VALUE_BYTES  = 3; /* FLAGS + up to two bytes for heart-rate */
00152         static const unsigned FLAGS_BYTE_INDEX = 0;
00153 
00154         static const unsigned VALUE_FORMAT_BITNUM = 0;
00155         static const uint8_t  VALUE_FORMAT_FLAG   = (1 << VALUE_FORMAT_BITNUM);
00156 
00157         HeartRateValueBytes(uint8_t hrmCounter) : valueBytes() {
00158             updateHeartRate(hrmCounter);
00159         }
00160 
00161         HeartRateValueBytes(uint16_t hrmCounter) : valueBytes() {
00162             updateHeartRate(hrmCounter);
00163         }
00164 
00165         void updateHeartRate(uint8_t hrmCounter) {
00166             valueBytes[FLAGS_BYTE_INDEX]    &= ~VALUE_FORMAT_FLAG;
00167             valueBytes[FLAGS_BYTE_INDEX + 1] = hrmCounter;
00168         }
00169 
00170         void updateHeartRate(uint16_t hrmCounter) {
00171             valueBytes[FLAGS_BYTE_INDEX]    |= VALUE_FORMAT_FLAG;
00172             valueBytes[FLAGS_BYTE_INDEX + 1] = (uint8_t)(hrmCounter & 0xFF);
00173             valueBytes[FLAGS_BYTE_INDEX + 2] = (uint8_t)(hrmCounter >> 8);
00174         }
00175 
00176         uint8_t       *getPointer(void) {
00177             return valueBytes;
00178         }
00179 
00180         const uint8_t *getPointer(void) const {
00181             return valueBytes;
00182         }
00183 
00184         unsigned       getNumValueBytes(void) const {
00185             return 1 + ((valueBytes[FLAGS_BYTE_INDEX] & VALUE_FORMAT_FLAG) ? sizeof(uint16_t) : sizeof(uint8_t));
00186         }
00187 
00188 private:
00189         /* First byte = 8-bit values, no extra info, Second byte = uint8_t HRM value */
00190         /* See --> https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.heart_rate_measurement.xml */
00191         uint8_t valueBytes[MAX_VALUE_BYTES];
00192     };
00193 
00194 private:
00195     BLEDevice           &ble;
00196     HeartRateValueBytes  valueBytes;
00197     uint8_t              controlPointValue;
00198     GattCharacteristic   hrmRate;
00199     GattCharacteristic   hrmLocation;
00200     GattCharacteristic   controlPoint;
00201 };
00202 
00203 #endif /* #ifndef __BLE_HEART_RATE_SERVICE_H__*/