Demonstration of the GAP profile. It shows advertising, scanning and connecting. The demo will cycle through several modes and print over the serial connection information about current activity.

GAP - Advertising, Scanning, Connecting

Demonstration of GAP API usage. It shows advertising, scanning and connecting. The demo will cycle through several modes and print over the serial connection information about current activity.

Running the application

Requirements

The sample application can be seen on any BLE scanner on a smartphone. If you don't have a scanner on your phone, please install :

- nRF Master Control Panel for Android.

- LightBlue for iPhone.

Information about activity is printed over the serial connection - please have a client open. You may use:

- Tera Term

Hardware requirements are in the main readme.

Building instructions

Building instructions for all samples are in the main readme.

source/main.cpp

Committer:
mbed_official
Date:
4 months ago
Revision:
12:3993e2608615
Parent:
11:37872bf83624
Child:
16:4dd4ecbc8efb

File content as of revision 12:3993e2608615:

/* 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.
 */

#include <events/mbed_events.h>
#include <mbed.h>
#include "ble/BLE.h"

/** This example demonstrates all the basic setup required
 *  to advertise, scan and connect to other devices.
 *
 *  It contains a single class that performs both scans and advertisements.
 *
 *  The demonstrations happens in sequence, after each "mode" ends
 *  the demo jumps to the next mode to continue. There are several modes
 *  that show scanning and several showing advertising. These are configured
 *  according to the two arrays containing parameters. During scanning
 *  a connection will be made to a connectable device upon its discovery.
 */

static const uint8_t DEVICE_NAME[]        = "GAP_device";

/* Duration of each mode in milliseconds */
static const size_t MODE_DURATION_MS      = 6000;

/* Time between each mode in milliseconds */
static const size_t TIME_BETWEEN_MODES_MS = 2000;

/* how long to wait before disconnecting in milliseconds */
static const size_t CONNECTION_DURATION = 3000;

typedef struct {
    GapAdvertisingParams::AdvertisingType_t adv_type;
    uint16_t interval;
    uint16_t timeout;
} AdvModeParam_t;

typedef struct {
    uint16_t interval;
    uint16_t window;
    uint16_t timeout;
    bool active;
} ScanModeParam_t;

/** the entries in this array are used to configure our advertising
 *  parameters for each of the modes we use in our demo */
static const AdvModeParam_t advertising_params[] = {
    /*            advertising type                        interval  timeout */
    { GapAdvertisingParams::ADV_CONNECTABLE_UNDIRECTED,      40,/*ms*/ 3/*s*/},
    { GapAdvertisingParams::ADV_SCANNABLE_UNDIRECTED,       100,       4     },
    { GapAdvertisingParams::ADV_NON_CONNECTABLE_UNDIRECTED, 100,       0     }
};

/* when we cycle through all our advertising modes we will move to scanning modes */

/** the entries in this array are used to configure our scanning
 *  parameters for each of the modes we use in our demo */
static const ScanModeParam_t scanning_params[] = {
/* interval      window    timeout       active */
    {   4,/*ms*/   4,/*ms*/   0,/*s*/    false },
    { 160,       100,         3,         false },
    { 160,        40,         0,         true  },
    { 500,        10,         0,         false }
};

/* parameters to use when attempting to connect to maximise speed of connection */
static const GapScanningParams connection_scan_params(
    GapScanningParams::SCAN_INTERVAL_MAX,
    GapScanningParams::SCAN_WINDOW_MAX,
    3,
    false
);

/* get number of items in our arrays */
static const size_t SCAN_PARAM_SET_MAX =
    sizeof(scanning_params) / sizeof(GapScanningParams);
static const size_t ADV_PARAM_SET_MAX  =
    sizeof(advertising_params) / sizeof(GapAdvertisingParams);

static const char* to_string(Gap::Phy_t phy) {
    switch(phy.value()) {
        case Gap::Phy_t::LE_1M:
            return "LE 1M";
        case Gap::Phy_t::LE_2M:
            return "LE 2M";
        case Gap::Phy_t::LE_CODED:
            return "LE coded";
        default:
            return "invalid PHY";
    }
}

/** Demonstrate advertising, scanning and connecting
 */
class GAPDevice : private mbed::NonCopyable<GAPDevice>, public Gap::EventHandler
{
public:
    GAPDevice() :
        _ble(BLE::Instance()),
        _led1(LED1, 0),
        _set_index(0),
        _is_in_scanning_mode(false),
        _is_connecting(false),
        _on_duration_end_id(0),
        _scan_count(0) { };

    ~GAPDevice()
    {
        if (_ble.hasInitialized()) {
            _ble.shutdown();
        }
    };

    /** Start BLE interface initialisation */
    void run()
    {
        ble_error_t error;

        if (_ble.hasInitialized()) {
            printf("Ble instance already initialised.\r\n");
            return;
        }

        /* this will inform us off all events so we can schedule their handling
         * using our event queue */
        _ble.onEventsToProcess(
            makeFunctionPointer(this, &GAPDevice::schedule_ble_events)
        );

        /* handle timeouts, for example when connection attempts fail */
        _ble.gap().onTimeout(
            makeFunctionPointer(this, &GAPDevice::on_timeout)
        );

        /* handle gap events */
        _ble.gap().setEventHandler(this);

        error = _ble.init(this, &GAPDevice::on_init_complete);

        if (error) {
            printf("Error returned by BLE::init.\r\n");
            return;
        }

        /* to show we're running we'll blink every 500ms */
        _event_queue.call_every(500, this, &GAPDevice::blink);

        /* this will not return until shutdown */
        _event_queue.dispatch_forever();
    };

private:
    /** This is called when BLE interface is initialised and starts the first mode */
    void on_init_complete(BLE::InitializationCompleteCallbackContext *event)
    {
        if (event->error) {
            printf("Error during the initialisation\r\n");
            return;
        }

        /* print device address */
        Gap::AddressType_t addr_type;
        Gap::Address_t addr;
        _ble.gap().getAddress(&addr_type, addr);
        printf("Device address: %02x:%02x:%02x:%02x:%02x:%02x\r\n",
               addr[5], addr[4], addr[3], addr[2], addr[1], addr[0]);

        /* setup the default phy used in connection to 2M to reduce power consumption */
        Gap::PhySet_t tx_phys(/* 1M */ false, /* 2M */ true, /* coded */ false);
        Gap::PhySet_t rx_phys(/* 1M */ false, /* 2M */ true, /* coded */ false);
        ble_error_t err = _ble.gap().setPreferredPhys(&tx_phys, &rx_phys);
        if (err) {
            printf("INFO: GAP::setPreferedPhys failed with error code %s", BLE::errorToString(err));
        }

        /* all calls are serialised on the user thread through the event queue */
        _event_queue.call(this, &GAPDevice::demo_mode_start);
    };

    /** queue up start of the current demo mode */
    void demo_mode_start()
    {
        if (_is_in_scanning_mode) {
            /* when scanning we want to connect to a peer device so we need to
             * attach callbacks that are used by Gap to notify us of events */
            _ble.gap().onConnection(this, &GAPDevice::on_connect);
            _ble.gap().onDisconnection(this, &GAPDevice::on_disconnect);

            _event_queue.call(this, &GAPDevice::scan);
        } else {
            _event_queue.call(this, &GAPDevice::advertise);
        }

        /* for performance measurement keep track of duration of the demo mode */
        _demo_duration.start();
        /* keep track of our state */
        _is_connecting = false;

        /* queue up next demo mode */
        _on_duration_end_id = _event_queue.call_in(
            MODE_DURATION_MS, this, &GAPDevice::on_duration_end
        );

        printf("\r\n");
    }

    /** Set up and start advertising */
    void advertise()
    {
        ble_error_t error;
        GapAdvertisingData advertising_data;

        /* add advertising flags */
        advertising_data.addFlags(GapAdvertisingData::LE_GENERAL_DISCOVERABLE
                                  | GapAdvertisingData::BREDR_NOT_SUPPORTED);

        /* add device name */
        advertising_data.addData(
            GapAdvertisingData::COMPLETE_LOCAL_NAME,
            DEVICE_NAME,
            sizeof(DEVICE_NAME)
        );

        error = _ble.gap().setAdvertisingPayload(advertising_data);

        if (error) {
            printf("Error during Gap::setAdvertisingPayload\r\n");
            return;
        }

        /* set the advertising parameters according to currently selected set,
         * see @AdvertisingType_t for explanation of modes */
        GapAdvertisingParams::AdvertisingType_t adv_type =
            advertising_params[_set_index].adv_type;

        /* how many milliseconds between advertisements, lower interval
         * increases the chances of being seen at the cost of more power */
        uint16_t interval = advertising_params[_set_index].interval;

        /* advertising will continue for this many seconds or until connected */
        uint16_t timeout = advertising_params[_set_index].timeout;

        _ble.gap().setAdvertisingType(adv_type);
        _ble.gap().setAdvertisingInterval(interval);
        _ble.gap().setAdvertisingTimeout(timeout);

        error = _ble.gap().startAdvertising();

        if (error) {
            printf("Error during Gap::startAdvertising.\r\n");
            return;
        }

        printf("Advertising started (type: 0x%x, interval: %dms, timeout: %ds)\r\n",
               adv_type, interval, timeout);
    };

    /** Set up and start scanning */
    void scan()
    {
        ble_error_t error;

        /* scanning happens repeatedly, interval is the number of milliseconds
         * between each cycle of scanning */
        uint16_t interval = scanning_params[_set_index].interval;

        /* number of milliseconds we scan for each time we enter
         * the scanning cycle after the interval set above */
        uint16_t window = scanning_params[_set_index].window;

        /* how long to repeat the cycles of scanning in seconds */
        uint16_t timeout = scanning_params[_set_index].timeout;

        /* active scanning will send a scan request to any scanable devices that
         * we see advertising */
        bool active = scanning_params[_set_index].active;

        /* set the scanning parameters according to currently selected set */
        error = _ble.gap().setScanParams(interval, window, timeout, active);

        if (error) {
            printf("Error during Gap::setScanParams\r\n");
            return;
        }

        /* start scanning and attach a callback that will handle advertisements
         * and scan requests responses */
        error = _ble.gap().startScan(this, &GAPDevice::on_scan);

        if (error) {
            printf("Error during Gap::startScan\r\n");
            return;
        }

        printf("Scanning started (interval: %dms, window: %dms, timeout: %ds).\r\n",
               interval, window, timeout);
    };

    /** After a set duration this cycles to the next demo mode
     *  unless a connection happened first */
    void on_duration_end()
    {
        print_performance();

        /* alloted time has elapsed, move to next demo mode */
        _event_queue.call(this, &GAPDevice::demo_mode_end);
    };

    /** Look at scan payload to find a peer device and connect to it */
    void on_scan(const Gap::AdvertisementCallbackParams_t *params)
    {
        /* keep track of scan events for performance reporting */
        _scan_count++;

        /* don't bother with analysing scan result if we're already connecting */
        if (_is_connecting) {
            return;
        }

        /* parse the advertising payload, looking for a discoverable device */
        for (uint8_t i = 0; i < params->advertisingDataLen; ++i) {
            /* The advertising payload is a collection of key/value records where
             * byte 0: length of the record excluding this byte
             * byte 1: The key, it is the type of the data
             * byte [2..N] The value. N is equal to byte0 - 1 */
            const uint8_t record_length = params->advertisingData[i];
            if (record_length == 0) {
                continue;
            }
            const uint8_t type = params->advertisingData[i + 1];
            const uint8_t *value = params->advertisingData + i + 2;

            /* connect to a discoverable device */
            if ((type == GapAdvertisingData::FLAGS)
                && (*value & GapAdvertisingData::LE_GENERAL_DISCOVERABLE)) {

                /* abort timeout as the mode will end on disconnection */
                _event_queue.cancel(_on_duration_end_id);

                printf("We found a connectable device\r\n");

                ble_error_t error = _ble.gap().connect(
                    params->peerAddr, Gap::ADDR_TYPE_RANDOM_STATIC,
                    NULL, &connection_scan_params
                );

                if (error) {
                    printf("Error during Gap::connect\r\n");
                    /* since no connection will be attempted end the mode */
                    _event_queue.call(this, &GAPDevice::demo_mode_end);
                    return;
                }

                /* we may have already scan events waiting
                 * to be processed so we need to remember
                 * that we are already connecting and ignore them */
                _is_connecting = true;

                return;
            }

            i += record_length;
        }
    };

    /** This is called by Gap to notify the application we connected,
     *  in our case it immediately disconnects */
    void on_connect(const Gap::ConnectionCallbackParams_t *connection_event)
    {
        print_performance();

        printf("Connected in %dms\r\n", _demo_duration.read_ms());

        /* cancel the connect timeout since we connected */
        _event_queue.cancel(_on_duration_end_id);

        _event_queue.call_in(
            CONNECTION_DURATION, &_ble.gap(), &Gap::disconnect, Gap::REMOTE_USER_TERMINATED_CONNECTION
        );
    };

    /** This is called by Gap to notify the application we disconnected,
     *  in our case it calls demo_mode_end() to progress the demo */
    void on_disconnect(const Gap::DisconnectionCallbackParams_t *event)
    {
        printf("Disconnected\r\n");

        /* we have successfully disconnected ending the demo, move to next mode */
        _event_queue.call(this, &GAPDevice::demo_mode_end);
    };

    /**
     * Implementation of Gap::EventHandler::onReadPhy
     */
    virtual void onReadPhy(
        ble_error_t error,
        Gap::Handle_t connectionHandle,
        Gap::Phy_t txPhy,
        Gap::Phy_t rxPhy
    ) {
        if (error) {
            printf(
                "Phy read on connection %d failed with error code %s\r\n",
                connectionHandle,
                BLE::errorToString(error)
            );
        } else {
            printf(
                "Phy read on connection %d - Tx Phy: %s, Rx Phy: %s\r\n",
                connectionHandle,
                to_string(txPhy),
                to_string(rxPhy)
            );
        }
    }

    /**
     * Implementation of Gap::EventHandler::onPhyUpdateComplete
     */
    virtual void onPhyUpdateComplete(
        ble_error_t error,
        Gap::Handle_t connectionHandle,
        Gap::Phy_t txPhy,
        Gap::Phy_t rxPhy
    ) {
        if (error) {
            printf(
                "Phy update on connection: %d failed with error code %s\r\n",
                connectionHandle,
                BLE::errorToString(error)
            );
        } else {
            printf(
                "Phy update on connection %d - Tx Phy: %s, Rx Phy: %s\r\n",
                connectionHandle,
                to_string(txPhy),
                to_string(rxPhy)
            );
        }
    }

    /** called if timeout is reached during advertising, scanning
     *  or connection initiation */
    void on_timeout(const Gap::TimeoutSource_t source)
    {
        _demo_duration.stop();

        switch (source) {
            case Gap::TIMEOUT_SRC_ADVERTISING:
                printf("Stopped advertising early due to timeout parameter\r\n");
                break;
            case Gap::TIMEOUT_SRC_SCAN:
                printf("Stopped scanning early due to timeout parameter\r\n");
                break;
            case Gap::TIMEOUT_SRC_CONN:
                printf("Failed to connect after scanning %d advertisements\r\n", _scan_count);
                _event_queue.call(this, &GAPDevice::print_performance);
                _event_queue.call(this, &GAPDevice::demo_mode_end);
                break;
            default:
                printf("Unexpected timeout\r\n");
                break;
        }
    };

    /** clean up after last run, cycle to the next mode and launch it */
    void demo_mode_end()
    {
        /* reset the demo ready for the next mode */
        _scan_count = 0;
        _demo_duration.stop();
        _demo_duration.reset();

        /* cycle through all demo modes */
        _set_index++;

        /* switch between advertising and scanning when we go
         * through all the params in the array */
        if (_set_index >= (_is_in_scanning_mode? SCAN_PARAM_SET_MAX : ADV_PARAM_SET_MAX)) {
            _set_index = 0;
            _is_in_scanning_mode = !_is_in_scanning_mode;
        }

        _ble.shutdown();
        _event_queue.break_dispatch();
    };

    /** print some information about our radio activity */
    void print_performance()
    {
        /* measure time from mode start, may have been stopped by timeout */
        uint16_t duration = _demo_duration.read_ms();

        if (_is_in_scanning_mode) {
            /* convert ms into timeslots for accurate calculation as internally
             * all durations are in timeslots (0.625ms) */
            uint16_t interval_ts = GapScanningParams::MSEC_TO_SCAN_DURATION_UNITS(
                scanning_params[_set_index].interval
            );
            uint16_t window_ts = GapScanningParams::MSEC_TO_SCAN_DURATION_UNITS(
                scanning_params[_set_index].window
            );
            uint16_t duration_ts = GapScanningParams::MSEC_TO_SCAN_DURATION_UNITS(
                duration
            );
            /* this is how long we scanned for in timeslots */
            uint16_t rx_ts = (duration_ts / interval_ts) * window_ts;
            /* convert to milliseconds */
            uint16_t rx_ms = (rx_ts * GapScanningParams::UNIT_0_625_MS) / 1000;

            printf("We have scanned for %dms with an interval of %d"
                    " timeslot and a window of %d timeslots\r\n",
                    duration, interval_ts, window_ts);

            printf("We have been listening on the radio for at least %dms\r\n", rx_ms);

        } else /* advertising */ {

            /* convert ms into timeslots for accurate calculation as internally
             * all durations are in timeslots (0.625ms) */
            uint16_t interval_ts = GapAdvertisingParams::MSEC_TO_ADVERTISEMENT_DURATION_UNITS(
                advertising_params[_set_index].interval
            );
            uint16_t duration_ts = GapAdvertisingParams::MSEC_TO_ADVERTISEMENT_DURATION_UNITS(
                duration
            );
            /* this is how many times we advertised */
            uint16_t events = duration_ts / interval_ts;

            printf("We have advertised for %dms"
                   " with an interval of %d timeslots\r\n",
                   duration, interval_ts);

            /* non-scannable and non-connectable advertising
             * skips rx events saving on power consumption */
            if (advertising_params[_set_index].adv_type
                == GapAdvertisingParams::ADV_NON_CONNECTABLE_UNDIRECTED) {
                printf("We created at least %d tx events\r\n", events);
            } else {
                printf("We created at least %d tx and rx events\r\n", events);
            }
        }
    };

    /** Schedule processing of events from the BLE middleware in the event queue. */
    void schedule_ble_events(BLE::OnEventsToProcessCallbackContext *context)
    {
        _event_queue.call(mbed::callback(&context->ble, &BLE::processEvents));
    };

    /** Blink LED to show we're running */
    void blink(void)
    {
        _led1 = !_led1;
    };

private:
    BLE                &_ble;
    events::EventQueue  _event_queue;
    DigitalOut          _led1;

    /* Keep track of our progress through demo modes */
    size_t              _set_index;
    bool                _is_in_scanning_mode;
    bool                _is_connecting;

    /* Remember the call id of the function on _event_queue
     * so we can cancel it if we need to end the mode early */
    int                 _on_duration_end_id;

    /* Measure performance of our advertising/scanning */
    Timer               _demo_duration;
    size_t              _scan_count;
};

int main()
{
    GAPDevice gap_device;

    while (1) {
        gap_device.run();
        wait_ms(TIME_BETWEEN_MODES_MS);
        printf("\r\nStarting next GAP demo mode\r\n");
    };

    return 0;
}