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_READ | GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_NOTIFY),
00062         hrmLocation(GattCharacteristic::UUID_BODY_SENSOR_LOCATION_CHAR, &location),
00063         controlPoint(GattCharacteristic::UUID_HEART_RATE_CONTROL_POINT_CHAR, &controlPointValue) {
00064         setupService();
00065     }
00066 
00067     /**
00068      * @brief Constructor with a 16-bit HRM Counter value.
00069      *
00070      * @param[in] _ble
00071      *               Reference to the underlying BLEDevice.
00072      * @param[in] hrmCounter (8-bit)
00073      *               initial value for the hrm counter.
00074      * @param[in] location
00075      *               Sensor's location.
00076      */
00077     HeartRateService(BLEDevice &_ble, uint16_t hrmCounter, uint8_t location) :
00078         ble(_ble),
00079         valueBytes(hrmCounter),
00080         hrmRate(GattCharacteristic::UUID_HEART_RATE_MEASUREMENT_CHAR, valueBytes.getPointer(),
00081                 valueBytes.getNumValueBytes(), HeartRateValueBytes::MAX_VALUE_BYTES,
00082                 GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_NOTIFY),
00083         hrmLocation(GattCharacteristic::UUID_BODY_SENSOR_LOCATION_CHAR, &location),
00084         controlPoint(GattCharacteristic::UUID_HEART_RATE_CONTROL_POINT_CHAR, &controlPointValue) {
00085         setupService();
00086     }
00087 
00088     /**
00089      * @brief Set a new 8-bit value for heart rate.
00090      *
00091      * @param[in] hrmCounter
00092      *                  HeartRate in bpm.
00093      */
00094     void updateHeartRate(uint8_t hrmCounter) {
00095         valueBytes.updateHeartRate(hrmCounter);
00096         ble.updateCharacteristicValue (hrmRate.getValueAttribute().getHandle(), valueBytes.getPointer(), valueBytes.getNumValueBytes());
00097     }
00098 
00099     /**
00100      * Set a new 16-bit value for heart rate.
00101      *
00102      * @param[in] hrmCounter
00103      *                  HeartRate in bpm.
00104      */
00105     void updateHeartRate(uint16_t hrmCounter) {
00106         valueBytes.updateHeartRate(hrmCounter);
00107         ble.updateCharacteristicValue (hrmRate.getValueAttribute().getHandle(), valueBytes.getPointer(), valueBytes.getNumValueBytes());
00108     }
00109 
00110     /**
00111      * This callback allows the HeartRateService to receive updates to the
00112      * controlPoint Characteristic.
00113      *
00114      * @param[in] params
00115      *     Information about the characterisitc being updated.
00116      */
00117     virtual void onDataWritten(const GattCharacteristicWriteCBParams *params) {
00118         if (params->charHandle == controlPoint.getValueAttribute().getHandle()) {
00119             /* Do something here if the new value is 1; else you can override this method by
00120              * extending this class.
00121              * @NOTE: if you are extending this class, be sure to also call
00122              * ble.onDataWritten(this, &ExtendedHRService::onDataWritten); in
00123              * your constructor.
00124              */
00125         }
00126     }
00127 
00128 private:
00129     void setupService(void) {
00130         static bool serviceAdded = false; /* We should only ever need to add the heart rate service once. */
00131         if (serviceAdded) {
00132             return;
00133         }
00134 
00135         GattCharacteristic *charTable[] = {&hrmRate, &hrmLocation, &controlPoint};
00136         GattService         hrmService(GattService::UUID_HEART_RATE_SERVICE, charTable, sizeof(charTable) / sizeof(GattCharacteristic *));
00137 
00138         ble.addService(hrmService);
00139         serviceAdded = true;
00140 
00141         ble.onDataWritten(this, &HeartRateService::onDataWritten);
00142     }
00143 
00144 private:
00145     /* Private internal representation for the bytes used to work with the vaulue of the heart-rate characteristic. */
00146     struct HeartRateValueBytes {
00147         static const unsigned MAX_VALUE_BYTES  = 3; /* FLAGS + up to two bytes for heart-rate */
00148         static const unsigned FLAGS_BYTE_INDEX = 0;
00149 
00150         static const unsigned VALUE_FORMAT_BITNUM = 0;
00151         static const uint8_t  VALUE_FORMAT_FLAG   = (1 << VALUE_FORMAT_BITNUM);
00152 
00153         HeartRateValueBytes(uint8_t hrmCounter) : valueBytes() {
00154             updateHeartRate(hrmCounter);
00155         }
00156 
00157         HeartRateValueBytes(uint16_t hrmCounter) : valueBytes() {
00158             updateHeartRate(hrmCounter);
00159         }
00160 
00161         void updateHeartRate(uint8_t hrmCounter) {
00162             valueBytes[FLAGS_BYTE_INDEX]    &= ~VALUE_FORMAT_FLAG;
00163             valueBytes[FLAGS_BYTE_INDEX + 1] = hrmCounter;
00164         }
00165 
00166         void updateHeartRate(uint16_t hrmCounter) {
00167             valueBytes[FLAGS_BYTE_INDEX]    |= VALUE_FORMAT_FLAG;
00168             valueBytes[FLAGS_BYTE_INDEX + 1] = (uint8_t)(hrmCounter & 0xFF);
00169             valueBytes[FLAGS_BYTE_INDEX + 2] = (uint8_t)(hrmCounter >> 8);
00170         }
00171 
00172         uint8_t       *getPointer(void) {
00173             return valueBytes;
00174         }
00175 
00176         const uint8_t *getPointer(void) const {
00177             return valueBytes;
00178         }
00179 
00180         unsigned       getNumValueBytes(void) const {
00181             return 1 + ((valueBytes[FLAGS_BYTE_INDEX] & VALUE_FORMAT_FLAG) ? sizeof(uint16_t) : sizeof(uint8_t));
00182         }
00183 
00184 private:
00185         /* First byte = 8-bit values, no extra info, Second byte = uint8_t HRM value */
00186         /* See --> https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.heart_rate_measurement.xml */
00187         uint8_t valueBytes[MAX_VALUE_BYTES];
00188     };
00189 
00190 private:
00191     BLEDevice           &ble;
00192 
00193     HeartRateValueBytes  valueBytes;
00194     uint8_t              controlPointValue;
00195 
00196     GattCharacteristic                   hrmRate;
00197     ReadOnlyGattCharacteristic<uint8_t>  hrmLocation;
00198     WriteOnlyGattCharacteristic<uint8_t> controlPoint;
00199 };
00200 
00201 #endif /* #ifndef __BLE_HEART_RATE_SERVICE_H__*/