Diff: ble/Gap.h

Revision:

710:b2e1a2660ec2

Child:

725:f4a355b35cf8

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ble/Gap.h	Fri Jun 19 15:53:28 2015 +0100
@@ -0,0 +1,886 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2013 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef __GAP_H__
+#define __GAP_H__
+
+#include "GapAdvertisingData.h"
+#include "GapAdvertisingParams.h"
+#include "GapScanningParams.h"
+#include "GapEvents.h"
+#include "CallChain.h"
+#include "FunctionPointerWithContext.h"
+
+using namespace mbed;
+
+/* Forward declarations for classes which will only be used for pointers or references in the following. */
+class GapAdvertisingParams;
+class GapScanningParams;
+class GapAdvertisingData;
+
+class Gap {
+public:
+    enum AddressType_t {
+        ADDR_TYPE_PUBLIC = 0,
+        ADDR_TYPE_RANDOM_STATIC,
+        ADDR_TYPE_RANDOM_PRIVATE_RESOLVABLE,
+        ADDR_TYPE_RANDOM_PRIVATE_NON_RESOLVABLE
+    };
+    typedef enum AddressType_t addr_type_t; /* @Note: deprecated. Use AddressType_t instead. */
+
+    static const unsigned ADDR_LEN = 6;
+    typedef uint8_t Address_t[ADDR_LEN]; /* 48-bit address, LSB format. */
+    typedef Address_t address_t;         /* @Note: deprecated. Use Address_t instead. */
+
+    enum TimeoutSource_t {
+        TIMEOUT_SRC_ADVERTISING      = 0x00, /**< Advertising timeout. */
+        TIMEOUT_SRC_SECURITY_REQUEST = 0x01, /**< Security request timeout. */
+        TIMEOUT_SRC_SCAN             = 0x02, /**< Scanning timeout. */
+        TIMEOUT_SRC_CONN             = 0x03, /**< Connection timeout. */
+    };
+
+    /**
+     * Enumeration for disconnection reasons. The values for these reasons are
+     * derived from Nordic's implementation; but the reasons are meant to be
+     * independent of the transport. If you are returned a reason which is not
+     * covered by this enumeration, then please refer to the underlying
+     * transport library.
+     */
+    enum DisconnectionReason_t {
+        CONNECTION_TIMEOUT                          = 0x08,
+        REMOTE_USER_TERMINATED_CONNECTION           = 0x13,
+        REMOTE_DEV_TERMINATION_DUE_TO_LOW_RESOURCES = 0x14,  /**< Remote Device Terminated Connection due to low resources.*/
+        REMOTE_DEV_TERMINATION_DUE_TO_POWER_OFF     = 0x15,  /**< Remote Device Terminated Connection due to power off. */
+        LOCAL_HOST_TERMINATED_CONNECTION            = 0x16,
+        CONN_INTERVAL_UNACCEPTABLE                  = 0x3B,
+    };
+
+    /* Describes the current state of the device (more than one bit can be set) */
+    struct GapState_t {
+        unsigned advertising : 1; /**< peripheral is currently advertising */
+        unsigned connected   : 1; /**< peripheral is connected to a central */
+    };
+
+    typedef uint16_t Handle_t; /* Type for connection handle. */
+
+    typedef struct {
+        uint16_t minConnectionInterval;      /**< Minimum Connection Interval in 1.25 ms units, see @ref BLE_GAP_CP_LIMITS.*/
+        uint16_t maxConnectionInterval;      /**< Maximum Connection Interval in 1.25 ms units, see @ref BLE_GAP_CP_LIMITS.*/
+        uint16_t slaveLatency;               /**< Slave Latency in number of connection events, see @ref BLE_GAP_CP_LIMITS.*/
+        uint16_t connectionSupervisionTimeout; /**< Connection Supervision Timeout in 10 ms units, see @ref BLE_GAP_CP_LIMITS.*/
+    } ConnectionParams_t;
+
+    enum Role_t {
+        PERIPHERAL  = 0x1, /**< Peripheral Role. */
+        CENTRAL     = 0x2, /**< Central Role.    */
+    };
+
+    struct AdvertisementCallbackParams_t {
+        Address_t            peerAddr;
+        int8_t               rssi;
+        bool                 isScanResponse;
+        GapAdvertisingParams::AdvertisingType_t type;
+        uint8_t              advertisingDataLen;
+        const uint8_t       *advertisingData;
+    };
+    typedef FunctionPointerWithContext<const AdvertisementCallbackParams_t *> AdvertisementReportCallback_t;
+
+    struct ConnectionCallbackParams_t {
+        Handle_t      handle;
+        Role_t        role;
+        AddressType_t peerAddrType;
+        Address_t     peerAddr;
+        AddressType_t ownAddrType;
+        Address_t     ownAddr;
+        const ConnectionParams_t *connectionParams;
+
+        ConnectionCallbackParams_t(Handle_t       handleIn,
+                                   Role_t         roleIn,
+                                   AddressType_t  peerAddrTypeIn,
+                                   const uint8_t *peerAddrIn,
+                                   AddressType_t  ownAddrTypeIn,
+                                   const uint8_t *ownAddrIn,
+                                   const ConnectionParams_t *connectionParamsIn) :
+            handle(handleIn),
+            role(roleIn),
+            peerAddrType(peerAddrTypeIn),
+            peerAddr(),
+            ownAddrType(ownAddrTypeIn),
+            ownAddr(),
+            connectionParams(connectionParamsIn) {
+            memcpy(peerAddr, peerAddrIn, ADDR_LEN);
+            memcpy(ownAddr, ownAddrIn, ADDR_LEN);
+        }
+    };
+
+    static const uint16_t UNIT_1_25_MS  = 1250; /**< Number of microseconds in 1.25 milliseconds. */
+    static const uint16_t UNIT_0_625_MS = 625;  /**< Number of microseconds in 0.625 milliseconds. */
+    static uint16_t MSEC_TO_GAP_DURATION_UNITS(uint32_t durationInMillis) {
+        return (durationInMillis * 1000) / UNIT_1_25_MS;
+    }
+    static uint16_t MSEC_TO_ADVERTISEMENT_DURATION_UNITS(uint32_t durationInMillis) {
+        return (durationInMillis * 1000) / UNIT_0_625_MS;
+    }
+    static uint16_t ADVERTISEMENT_DURATION_UNITS_TO_MS(uint16_t gapUnits) {
+        return (gapUnits * UNIT_0_625_MS) / 1000;
+    }
+
+    typedef void (*TimeoutEventCallback_t)(TimeoutSource_t source);
+    typedef void (*ConnectionEventCallback_t)(const ConnectionCallbackParams_t *params);
+    typedef void (*DisconnectionEventCallback_t)(Handle_t, DisconnectionReason_t);
+    typedef void (*RadioNotificationEventCallback_t)(bool radio_active); /* gets passed true for ACTIVE; false for INACTIVE. */
+
+    /*
+     * The following functions are meant to be overridden in the platform-specific sub-class.
+     */
+public:
+    /**
+     * Set the BTLE MAC address and type. Please note that the address format is
+     * LSB (least significant byte first). Please refer to Address_t.
+     *
+     * @return BLE_ERROR_NONE on success.
+     */
+    virtual ble_error_t setAddress(AddressType_t type, const Address_t address) {
+        return BLE_ERROR_NOT_IMPLEMENTED; /* default implementation; override this API if this capability is supported. */
+    }
+
+    /**
+     * Fetch the BTLE MAC address and type.
+     *
+     * @return BLE_ERROR_NONE on success.
+     */
+    virtual ble_error_t getAddress(AddressType_t *typeP, Address_t address) {
+        return BLE_ERROR_NOT_IMPLEMENTED; /* default implementation; override this API if this capability is supported. */
+    }
+
+    /**
+     * @return Minimum Advertising interval in milliseconds.
+     */
+    virtual uint16_t getMinAdvertisingInterval(void) const {
+        return 0; /* default implementation; override this API if this capability is supported. */
+    }
+
+    /**
+     * @return Minimum Advertising interval in milliseconds for non-connectible mode.
+     */
+    virtual uint16_t getMinNonConnectableAdvertisingInterval(void) const {
+        return 0; /* default implementation; override this API if this capability is supported. */
+    }
+
+    /**
+     * @return Maximum Advertising interval in milliseconds.
+     */
+    virtual uint16_t getMaxAdvertisingInterval(void) const {
+        return 0xFFFF; /* default implementation; override this API if this capability is supported. */
+    }
+
+    virtual ble_error_t stopAdvertising(void) {
+        return BLE_ERROR_NOT_IMPLEMENTED; /* default implementation; override this API if this capability is supported. */
+    }
+
+    /**
+     * Stop scanning. The current scanning parameters remain in effect.
+     *
+     * @retval BLE_ERROR_NONE if successfully stopped scanning procedure.
+     */
+    virtual ble_error_t stopScan() {
+        return BLE_ERROR_NOT_IMPLEMENTED; /* default implementation; override this API if this capability is supported. */
+    }
+
+    /**
+     * Create a connection (GAP Link Establishment).
+     *
+     * @param peerAddr
+     *          48-bit address, LSB format.
+     * @param peerAddrType
+     *          Address type of the peer.
+     * @param connectionParams
+     *         Connection parameters.
+     * @param scanParams
+     *          Paramters to be used while scanning for the peer.
+     * @return  BLE_ERROR_NONE if connection establishment procedure is started
+     *     successfully. The connectionCallback (if set) will be invoked upon
+     *     a connection event.
+     */
+    virtual ble_error_t connect(const Address_t           peerAddr,
+                                Gap::AddressType_t        peerAddrType,
+                                const ConnectionParams_t *connectionParams,
+                                const GapScanningParams  *scanParams) {
+        return BLE_ERROR_NOT_IMPLEMENTED; /* default implementation; override this API if this capability is supported. */
+    }
+
+    /**
+     * This call initiates the disconnection procedure, and its completion will
+     * be communicated to the application with an invocation of the
+     * disconnectionCallback.
+     *
+     * @param  reason
+     *           The reason for disconnection to be sent back to the peer.
+     */
+    virtual ble_error_t disconnect(Handle_t connectionHandle, DisconnectionReason_t reason) {
+        return BLE_ERROR_NOT_IMPLEMENTED; /* default implementation; override this API if this capability is supported. */
+    }
+
+    /**
+     * This call initiates the disconnection procedure, and its completion will
+     * be communicated to the application with an invocation of the
+     * disconnectionCallback.
+     *
+     * @param  reason
+     *           The reason for disconnection to be sent back to the peer.
+     *
+     * @note: this version of disconnect() doesn't take a connection handle. It
+     * will work reliably only for stacks which are limited to a single
+     * connection. This API should be considered *deprecated* in favour of the
+     * altertive which takes a connection handle. It will be dropped in the future.
+     */
+    virtual ble_error_t disconnect(DisconnectionReason_t reason) {
+        return BLE_ERROR_NOT_IMPLEMENTED; /* default implementation; override this API if this capability is supported. */
+    }
+
+    /**
+     * Get the GAP peripheral preferred connection parameters. These are the
+     * defaults that the peripheral would like to have in a connection. The
+     * choice of the connection parameters is eventually up to the central.
+     *
+     * @param[out] params
+     *               The structure where the parameters will be stored. Memory
+     *               for this is owned by the caller.
+     *
+     * @return BLE_ERROR_NONE if the parameters were successfully filled into
+     * the given structure pointed to by params.
+     */
+    virtual ble_error_t getPreferredConnectionParams(ConnectionParams_t *params) {
+        return BLE_ERROR_NOT_IMPLEMENTED; /* default implementation; override this API if this capability is supported. */
+    }
+
+    /**
+     * Set the GAP peripheral preferred connection parameters. These are the
+     * defaults that the peripheral would like to have in a connection. The
+     * choice of the connection parameters is eventually up to the central.
+     *
+     * @param[in] params
+     *               The structure containing the desired parameters.
+     */
+    virtual ble_error_t setPreferredConnectionParams(const ConnectionParams_t *params) {
+        return BLE_ERROR_NOT_IMPLEMENTED; /* default implementation; override this API if this capability is supported. */
+    }
+
+    /**
+     * Update connection parameters while in the peripheral role.
+     * @details In the peripheral role, this will send the corresponding L2CAP request to the connected peer and wait for
+     *          the central to perform the procedure.
+     * @param[in] handle
+     *              Connection Handle
+     * @param[in] params
+     *              Pointer to desired connection parameters. If NULL is provided on a peripheral role,
+     *              the parameters in the PPCP characteristic of the GAP service will be used instead.
+     */
+    virtual ble_error_t updateConnectionParams(Handle_t handle, const ConnectionParams_t *params) {
+        return BLE_ERROR_NOT_IMPLEMENTED; /* default implementation; override this API if this capability is supported. */
+    }
+
+    /**
+     * Set the device name characteristic in the GAP service.
+     * @param[in] deviceName
+     *              The new value for the device-name. This is a UTF-8 encoded, <b>NULL-terminated</b> string.
+     */
+    virtual ble_error_t setDeviceName(const uint8_t *deviceName) {
+        return BLE_ERROR_NOT_IMPLEMENTED; /* default implementation; override this API if this capability is supported. */
+    }
+
+    /**
+     * Get the value of the device name characteristic in the GAP service.
+     * @param[out]    deviceName
+     *                  Pointer to an empty buffer where the UTF-8 *non NULL-
+     *                  terminated* string will be placed. Set this
+     *                  value to NULL in order to obtain the deviceName-length
+     *                  from the 'length' parameter.
+     *
+     * @param[in/out] lengthP
+     *                  (on input) Length of the buffer pointed to by deviceName;
+     *                  (on output) the complete device name length (without the
+     *                     null terminator).
+     *
+     * @note If the device name is longer than the size of the supplied buffer,
+     *     length will return the complete device name length, and not the
+     *     number of bytes actually returned in deviceName. The application may
+     *     use this information to retry with a suitable buffer size.
+     */
+    virtual ble_error_t getDeviceName(uint8_t *deviceName, unsigned *lengthP) {
+        return BLE_ERROR_NOT_IMPLEMENTED; /* default implementation; override this API if this capability is supported. */
+    }
+
+    /**
+     * Set the appearance characteristic in the GAP service.
+     * @param[in] appearance
+     *              The new value for the device-appearance.
+     */
+    virtual ble_error_t setAppearance(GapAdvertisingData::Appearance appearance) {
+        return BLE_ERROR_NOT_IMPLEMENTED; /* default implementation; override this API if this capability is supported. */
+    }
+
+    /**
+     * Get the appearance characteristic in the GAP service.
+     * @param[out] appearance
+     *               The new value for the device-appearance.
+     */
+    virtual ble_error_t getAppearance(GapAdvertisingData::Appearance *appearanceP) {
+        return BLE_ERROR_NOT_IMPLEMENTED; /* default implementation; override this API if this capability is supported. */
+    }
+
+    /**
+     * Set the radio's transmit power.
+     * @param[in] txPower Radio transmit power in dBm.
+     */
+    virtual ble_error_t setTxPower(int8_t txPower) {
+        return BLE_ERROR_NOT_IMPLEMENTED; /* default implementation; override this API if this capability is supported. */
+    }
+
+    /**
+     * Query the underlying stack for permitted arguments for setTxPower().
+     *
+     * @param[out] valueArrayPP
+     *                 Out parameter to receive the immutable array of Tx values.
+     * @param[out] countP
+     *                 Out parameter to receive the array's size.
+     */
+    virtual void getPermittedTxPowerValues(const int8_t **valueArrayPP, size_t *countP) {
+        *countP = 0; /* default implementation; override this API if this capability is supported. */
+    }
+
+protected:
+    /* Override the following in the underlying adaptation layer to provide the functionality of scanning. */
+    virtual ble_error_t startRadioScan(const GapScanningParams &scanningParams) {
+        return BLE_ERROR_NOT_IMPLEMENTED; /* default implementation; override this API if this capability is supported. */
+    }
+
+    /*
+     * APIs with non-virtual implementations.
+     */
+public:
+    /**
+     * Returns the current GAP state of the device using a bitmask which
+     * describes whether the device is advertising and/or connected.
+     */
+    GapState_t getState(void) const {
+        return state;
+    }
+
+    /**
+     * Set the GAP advertising mode to use for this device.
+     */
+    void setAdvertisingType(GapAdvertisingParams::AdvertisingType_t advType) {
+        _advParams.setAdvertisingType(advType);
+    }
+
+    /**
+     * @param[in] interval
+     *              Advertising interval in units of milliseconds. Advertising
+     *              is disabled if interval is 0. If interval is smaller than
+     *              the minimum supported value, then the minimum supported
+     *              value is used instead. This minimum value can be discovered
+     *              using getMinAdvertisingInterval().
+     *
+     *              This field must be set to 0 if connectionMode is equal
+     *              to ADV_CONNECTABLE_DIRECTED.
+     *
+     * @note: Decreasing this value will allow central devices to detect a
+     * peripheral faster at the expense of more power being used by the radio
+     * due to the higher data transmit rate.
+     *
+     * @note: This API is now *deprecated* and will be dropped in the future.
+     * You should use the parallel API from Gap directly. A former call to
+     * ble.setAdvertisingInterval(...) should now be achieved using
+     * ble.gap().setAdvertisingInterval(...).
+     *
+     * @Note: [WARNING] This API previously used 0.625ms as the unit for its
+     * 'interval' argument. That required an explicit conversion from
+     * milliseconds using Gap::MSEC_TO_GAP_DURATION_UNITS(). This conversion is
+     * no longer required as the new units are milliseconds. Any application
+     * code depending on the old semantics would need to be updated accordingly.
+     */
+    void setAdvertisingInterval(uint16_t interval) {
+        if (interval == 0) {
+            stopAdvertising();
+        } else if (interval < getMinAdvertisingInterval()) {
+            interval = getMinAdvertisingInterval();
+        }
+        _advParams.setInterval(MSEC_TO_ADVERTISEMENT_DURATION_UNITS(interval));
+    }
+
+    /**
+     * @param[in] timeout
+     *              Advertising timeout (in seconds) between 0x1 and 0x3FFF (1
+     *              and 16383). Use 0 to disable the advertising timeout.
+     */
+    void setAdvertisingTimeout(uint16_t timeout) {
+        _advParams.setTimeout(timeout);
+    }
+
+    /**
+     * Start advertising.
+     */
+    ble_error_t startAdvertising(void) {
+        setAdvertisingData(); /* update the underlying stack */
+        return startAdvertising(_advParams);
+    }
+
+    /**
+     * Reset any advertising payload prepared from prior calls to
+     * accumulateAdvertisingPayload(). This automatically propagates the re-
+     * initialized adv payload to the underlying stack.
+     *
+     * Note: This should be followed by a call to setAdvertisingPayload() or
+     * startAdvertising() before the update takes effect.
+     */
+    void clearAdvertisingPayload(void) {
+        _advPayload.clear();
+        setAdvertisingData();
+    }
+
+    /**
+     * Accumulate an AD structure in the advertising payload. Please note that
+     * the payload is limited to 31 bytes. The SCAN_RESPONSE message may be used
+     * as an additional 31 bytes if the advertising payload proves to be too
+     * small.
+     *
+     * @param[in] flags
+     *              The flags to be added. Please refer to
+     *              GapAdvertisingData::Flags for valid flags. Multiple
+     *              flags may be specified in combination.
+     */
+    ble_error_t accumulateAdvertisingPayload(uint8_t flags) {
+        ble_error_t rc;
+        if ((rc = _advPayload.addFlags(flags)) != BLE_ERROR_NONE) {
+            return rc;
+        }
+
+        return setAdvertisingData();
+    }
+
+    /**
+     * Accumulate an AD structure in the advertising payload. Please note that
+     * the payload is limited to 31 bytes. The SCAN_RESPONSE message may be used
+     * as an additional 31 bytes if the advertising payload proves to be too
+     * small.
+     *
+     * @param  app
+     *         The appearance of the peripheral.
+     */
+    ble_error_t accumulateAdvertisingPayload(GapAdvertisingData::Appearance app) {
+        setAppearance(app);
+
+        ble_error_t rc;
+        if ((rc = _advPayload.addAppearance(app)) != BLE_ERROR_NONE) {
+            return rc;
+        }
+
+        return setAdvertisingData();
+    }
+
+    /**
+     * Accumulate an AD structure in the advertising payload. Please note that
+     * the payload is limited to 31 bytes. The SCAN_RESPONSE message may be used
+     * as an additional 31 bytes if the advertising payload proves to be too
+     * small.
+     *
+     * @param  app
+     *         The max transmit power to be used by the controller. This is
+     *         only a hint.
+     */
+    ble_error_t accumulateAdvertisingPayloadTxPower(int8_t power) {
+        ble_error_t rc;
+        if ((rc = _advPayload.addTxPower(power)) != BLE_ERROR_NONE) {
+            return rc;
+        }
+
+        return setAdvertisingData();
+    }
+
+    /**
+     * Accumulate a variable length byte-stream as an AD structure in the
+     * advertising payload. Please note that the payload is limited to 31 bytes.
+     * The SCAN_RESPONSE message may be used as an additional 31 bytes if the
+     * advertising payload proves to be too small.
+     *
+     * @param  type The type which describes the variable length data.
+     * @param  data data bytes.
+     * @param  len  length of data.
+     */
+    ble_error_t accumulateAdvertisingPayload(GapAdvertisingData::DataType type, const uint8_t *data, uint8_t len) {
+        if (type == GapAdvertisingData::COMPLETE_LOCAL_NAME) {
+            setDeviceName(data);
+        }
+
+        ble_error_t rc;
+        if ((rc = _advPayload.addData(type, data, len)) != BLE_ERROR_NONE) {
+            return rc;
+        }
+
+        return setAdvertisingData();
+    }
+
+    /**
+     * Setup a particular, user-constructed advertisement payload for the
+     * underlying stack. It would be uncommon for this API to be used directly;
+     * there are other APIs to build an advertisement payload (see above).
+     */
+    ble_error_t setAdvertisingPayload(const GapAdvertisingData &payload) {
+        _advPayload = payload;
+        return setAdvertisingData();
+    }
+
+    /**
+     * @return  Read back advertising data. Useful for storing and
+     *          restoring payload.
+     */
+    const GapAdvertisingData &getAdvertisingPayload(void) const {
+        return _advPayload;
+    }
+
+    /**
+     * Accumulate a variable length byte-stream as an AD structure in the
+     * scanResponse payload.
+     *
+     * @param[in] type The type which describes the variable length data.
+     * @param[in] data data bytes.
+     * @param[in] len  length of data.
+     */
+    ble_error_t accumulateScanResponse(GapAdvertisingData::DataType type, const uint8_t *data, uint8_t len) {
+        ble_error_t rc;
+        if ((rc = _scanResponse.addData(type, data, len)) != BLE_ERROR_NONE) {
+            return rc;
+        }
+
+        return setAdvertisingData();
+    }
+
+    /**
+     * Reset any scan response prepared from prior calls to
+     * accumulateScanResponse().
+     *
+     * Note: This should be followed by a call to setAdvertisingPayload() or
+     * startAdvertising() before the update takes effect.
+     */
+    void clearScanResponse(void) {
+        _scanResponse.clear();
+        setAdvertisingData();
+    }
+
+    /**
+     * Setup parameters for GAP scanning--i.e. observer mode.
+     * @param[in] interval
+     *              Scan interval (in milliseconds) [valid values lie between 2.5ms and 10.24s].
+     * @param[in] window
+     *              Scan Window (in milliseconds) [valid values lie between 2.5ms and 10.24s].
+     * @param[in] timeout
+     *              Scan timeout (in seconds) between 0x0001 and 0xFFFF, 0x0000 disables timeout.
+     * @param[in] activeScanning
+     *              Set to True if active-scanning is required. This is used to fetch the
+     *              scan response from a peer if possible.
+     *
+     * The scanning window divided by the interval determines the duty cycle for
+     * scanning. For example, if the interval is 100ms and the window is 10ms,
+     * then the controller will scan for 10 percent of the time. It is possible
+     * to have the interval and window set to the same value. In this case,
+     * scanning is continuous, with a change of scanning frequency once every
+     * interval.
+     *
+     * Once the scanning parameters have been configured, scanning can be
+     * enabled by using startScan().
+     *
+     * @Note: The scan interval and window are recommendations to the BLE stack.
+     */
+    ble_error_t setScanParams(uint16_t interval       = GapScanningParams::SCAN_INTERVAL_MAX,
+                              uint16_t window         = GapScanningParams::SCAN_WINDOW_MAX,
+                              uint16_t timeout        = 0,
+                              bool     activeScanning = false) {
+        ble_error_t rc;
+        if (((rc = _scanningParams.setInterval(interval)) == BLE_ERROR_NONE) &&
+            ((rc = _scanningParams.setWindow(window))     == BLE_ERROR_NONE) &&
+            ((rc = _scanningParams.setTimeout(timeout))   == BLE_ERROR_NONE)) {
+            _scanningParams.setActiveScanning(activeScanning);
+            return BLE_ERROR_NONE;
+        }
+
+        return rc;
+    }
+
+    /**
+     * Setup the scanInterval parameter for GAP scanning--i.e. observer mode.
+     * @param[in] interval
+     *              Scan interval (in milliseconds) [valid values lie between 2.5ms and 10.24s].
+     *
+     * The scanning window divided by the interval determines the duty cycle for
+     * scanning. For example, if the interval is 100ms and the window is 10ms,
+     * then the controller will scan for 10 percent of the time. It is possible
+     * to have the interval and window set to the same value. In this case,
+     * scanning is continuous, with a change of scanning frequency once every
+     * interval.
+     *
+     * Once the scanning parameters have been configured, scanning can be
+     * enabled by using startScan().
+     */
+    ble_error_t setScanInterval(uint16_t interval) {
+        return _scanningParams.setInterval(interval);
+    }
+
+    /**
+     * Setup the scanWindow parameter for GAP scanning--i.e. observer mode.
+     * @param[in] window
+     *              Scan Window (in milliseconds) [valid values lie between 2.5ms and 10.24s].
+     *
+     * The scanning window divided by the interval determines the duty cycle for
+     * scanning. For example, if the interval is 100ms and the window is 10ms,
+     * then the controller will scan for 10 percent of the time. It is possible
+     * to have the interval and window set to the same value. In this case,
+     * scanning is continuous, with a change of scanning frequency once every
+     * interval.
+     *
+     * Once the scanning parameters have been configured, scanning can be
+     * enabled by using startScan().
+     */
+    ble_error_t setScanWindow(uint16_t window) {
+        return _scanningParams.setWindow(window);
+    }
+
+    /**
+     * Setup parameters for GAP scanning--i.e. observer mode.
+     * @param[in] timeout
+     *              Scan timeout (in seconds) between 0x0001 and 0xFFFF, 0x0000 disables timeout.
+     *
+     * Once the scanning parameters have been configured, scanning can be
+     * enabled by using startScan().
+     */
+    ble_error_t setScanTimeout(uint16_t timeout) {
+        return _scanningParams.setTimeout(timeout);
+    }
+
+    /**
+     * Setup parameters for GAP scanning--i.e. observer mode.
+     * @param[in] activeScanning
+     *              Set to True if active-scanning is required. This is used to fetch the
+     *              scan response from a peer if possible.
+     *
+     * Once the scanning parameters have been configured, scanning can be
+     * enabled by using startScan().
+     */
+    void setActiveScanning(bool activeScanning) {
+        _scanningParams.setActiveScanning(activeScanning);
+    }
+
+    /**
+     * Start scanning (Observer Procedure) based on the parameters currently in
+     * effect.
+     *
+     * @param[in] callback
+     *              The application specific callback to be invoked upon
+     *              receiving every advertisement report. This can be passed in
+     *              as NULL, in which case scanning may not be enabled at all.
+     */
+    ble_error_t startScan(void (*callback)(const AdvertisementCallbackParams_t *params)) {
+        ble_error_t err = BLE_ERROR_NONE;
+        if (callback) {
+            if ((err = startRadioScan(_scanningParams)) == BLE_ERROR_NONE) {
+                onAdvertisementReport.attach(callback);
+            }
+        }
+
+        return err;
+    }
+
+    /**
+     * Same as above, but this takes an (object, method) pair for a callback.
+     */
+    template<typename T>
+    ble_error_t startScan(T *object, void (T::*callbackMember)(const AdvertisementCallbackParams_t *params)) {
+        ble_error_t err = BLE_ERROR_NONE;
+        if (object && callbackMember) {
+            if ((err = startRadioScan(_scanningParams)) == BLE_ERROR_NONE) {
+                onAdvertisementReport.attach(object, callbackMember);
+            }
+        }
+
+        return err;
+    }
+
+private:
+    ble_error_t setAdvertisingData(void) {
+        return setAdvertisingData(_advPayload, _scanResponse);
+    }
+
+private:
+    virtual ble_error_t setAdvertisingData(const GapAdvertisingData &, const GapAdvertisingData &) = 0;
+    virtual ble_error_t startAdvertising(const GapAdvertisingParams &)                             = 0;
+
+public:
+    /**
+     * Accessors to read back currently active advertising params.
+     */
+    GapAdvertisingParams &getAdvertisingParams(void) {
+        return _advParams;
+    }
+    const GapAdvertisingParams &getAdvertisingParams(void) const {
+        return _advParams;
+    }
+
+    /**
+     * Setup a particular, user-constructed set of advertisement parameters for
+     * the underlying stack. It would be uncommon for this API to be used
+     * directly; there are other APIs to tweak advertisement parameters
+     * individually.
+     */
+    void setAdvertisingParams(const GapAdvertisingParams &newParams) {
+        _advParams = newParams;
+    }
+
+    /* Event callback handlers. */
+public:
+    /**
+     * Setup a callback for timeout events. Refer to TimeoutSource_t for
+     * possible event types.
+     */
+    void onTimeout(TimeoutEventCallback_t callback) {timeoutCallback = callback;}
+
+    /**
+     * Setup a callback for connection events. Refer to ConnectionEventCallback_t.
+     */
+    void onConnection(ConnectionEventCallback_t callback) {connectionCallback = callback;}
+
+    /**
+     * Set the application callback for disconnection events.
+     * @param callback
+     *        Pointer to the unique callback.
+     */
+    void onDisconnection(DisconnectionEventCallback_t callback) {disconnectionCallback = callback;}
+
+    /**
+     * Append to a chain of callbacks to be invoked upon disconnection; these
+     * callbacks receive no context and are therefore different from the
+     * disconnectionCallback callback.
+     * @param callback
+     *        function pointer to be invoked upon disconnection; receives no context.
+     */
+    template<typename T>
+    void addToDisconnectionCallChain(T *tptr, void (T::*mptr)(void)) {disconnectionCallChain.add(tptr, mptr);}
+
+    /**
+     * Set the application callback for radio-notification events.
+     *
+     * Radio Notification is a feature that enables ACTIVE and INACTIVE
+     * (nACTIVE) signals from the stack that notify the application when the
+     * radio is in use. The signal is sent using software interrupt.
+     *
+     * The ACTIVE signal is sent before the Radio Event starts. The nACTIVE
+     * signal is sent at the end of the Radio Event. These signals can be used
+     * by the application programmer to synchronize application logic with radio
+     * activity. For example, the ACTIVE signal can be used to shut off external
+     * devices to manage peak current drawn during periods when the radio is on,
+     * or to trigger sensor data collection for transmission in the Radio Event.
+     *
+     * @param callback
+     *          The application handler to be invoked in response to a radio
+     *          ACTIVE/INACTIVE event.
+     */
+    virtual void onRadioNotification(RadioNotificationEventCallback_t callback) {radioNotificationCallback = callback;}
+
+protected:
+    Gap() :
+        _advParams(),
+        _advPayload(),
+        _scanningParams(),
+        _scanResponse(),
+        state(),
+        timeoutCallback(NULL),
+        connectionCallback(NULL),
+        disconnectionCallback(NULL),
+        radioNotificationCallback(),
+        onAdvertisementReport(),
+        disconnectionCallChain() {
+        _advPayload.clear();
+        _scanResponse.clear();
+    }
+
+    /* Entry points for the underlying stack to report events back to the user. */
+public:
+    void processConnectionEvent(Handle_t                  handle,
+                                Role_t                    role,
+                                AddressType_t             peerAddrType,
+                                const Address_t           peerAddr,
+                                AddressType_t             ownAddrType,
+                                const Address_t           ownAddr,
+                                const ConnectionParams_t *connectionParams) {
+        state.connected = 1;
+        if (connectionCallback) {
+            ConnectionCallbackParams_t callbackParams(handle, role, peerAddrType, peerAddr, ownAddrType, ownAddr, connectionParams);
+            connectionCallback(&callbackParams);
+        }
+    }
+
+    void processDisconnectionEvent(Handle_t handle, DisconnectionReason_t reason) {
+        state.connected = 0;
+        if (disconnectionCallback) {
+            disconnectionCallback(handle, reason);
+        }
+        disconnectionCallChain.call();
+    }
+
+    void processAdvertisementReport(const Address_t    peerAddr,
+                                    int8_t             rssi,
+                                    bool               isScanResponse,
+                                    GapAdvertisingParams::AdvertisingType_t  type,
+                                    uint8_t            advertisingDataLen,
+                                    const uint8_t     *advertisingData) {
+        AdvertisementCallbackParams_t params;
+        memcpy(params.peerAddr, peerAddr, ADDR_LEN);
+        params.rssi               = rssi;
+        params.isScanResponse     = isScanResponse;
+        params.type               = type;
+        params.advertisingDataLen = advertisingDataLen;
+        params.advertisingData    = advertisingData;
+        onAdvertisementReport.call(&params);
+    }
+
+    void processTimeoutEvent(TimeoutSource_t source) {
+        if (timeoutCallback) {
+            timeoutCallback(source);
+        }
+    }
+
+protected:
+    GapAdvertisingParams             _advParams;
+    GapAdvertisingData               _advPayload;
+    GapScanningParams                _scanningParams;
+    GapAdvertisingData               _scanResponse;
+
+    GapState_t                       state;
+
+protected:
+    TimeoutEventCallback_t           timeoutCallback;
+    ConnectionEventCallback_t        connectionCallback;
+    DisconnectionEventCallback_t     disconnectionCallback;
+    RadioNotificationEventCallback_t radioNotificationCallback;
+    AdvertisementReportCallback_t    onAdvertisementReport;
+    CallChain                        disconnectionCallChain;
+
+private:
+    /* disallow copy and assignment */
+    Gap(const Gap &);
+    Gap& operator=(const Gap &);
+};
+
+#endif // ifndef __GAP_H__
\ No newline at end of file