Add example exercising the GattClient API.

BLE_GattClient/.mbed

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+ROOT=.
+TARGET=NRF52_DK

BLE_GattClient/BLEProcess.h

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+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2015 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 GATT_EXAMPLE_BLE_PROCESS_H_
+#define GATT_EXAMPLE_BLE_PROCESS_H_
+
+#include <stdint.h>
+#include <stdio.h>
+
+#include "events/Eventqueue.h"
+#include "platform/Callback.h"
+#include "platform/NonCopyable.h"
+
+#include "ble/BLE.h"
+#include "ble/Gap.h"
+#include "ble/GapAdvertisingParams.h"
+#include "ble/GapAdvertisingData.h"
+#include "ble/FunctionPointerWithContext.h"
+
+/**
+ * Handle initialization and shutdown of the BLE Instance.
+ *
+ * Setup advertising payload and manage advertising state.
+ * Delegate to GattClientProcess once the connection is established.
+ */
+class BLEProcess : private mbed::NonCopyable<BLEProcess> {
+public:
+    /**
+     * Construct a BLEProcess from an event queue and a ble interface.
+     *
+     * Call start() to initiate ble processing.
+     */
+    BLEProcess(events::EventQueue &event_queue, BLE &ble_interface) :
+        _event_queue(event_queue),
+        _ble_interface(ble_interface),
+        _post_init_cb() {
+    }
+
+    ~BLEProcess()
+    {
+        stop();
+    }
+
+    /**
+     * Initialize the ble interface, configure it and start advertising.
+     */
+    bool start()
+    {
+        printf("Ble process started.\r\n");
+
+        if (_ble_interface.hasInitialized()) {
+            printf("Error: the ble instance has already been initialized.\r\n");
+            return false;
+        }
+
+        _ble_interface.onEventsToProcess(
+            makeFunctionPointer(this, &BLEProcess::schedule_ble_events)
+        );
+
+        ble_error_t error = _ble_interface.init(
+            this, &BLEProcess::when_init_complete
+        );
+
+        if (error) {
+            printf("Error: %u returned by BLE::init.\r\n", error);
+            return false;
+        }
+
+        return true;
+    }
+
+    /**
+     * Close existing connections and stop the process.
+     */
+    void stop()
+    {
+        if (_ble_interface.hasInitialized()) {
+            _ble_interface.shutdown();
+            printf("Ble process stopped.");
+        }
+    }
+
+    /**
+     * Subscription to the ble interface initialization event.
+     *
+     * @param[in] cb The callback object that will be called when the ble
+     * interface is initialized.
+     */
+    void on_init(mbed::Callback<void(BLE&, events::EventQueue&)> cb)
+    {
+        _post_init_cb = cb;
+    }
+
+private:
+    /**
+     * Sets up adverting payload and start advertising.
+     *
+     * This function is invoked when the ble interface is initialized.
+     */
+    void when_init_complete(BLE::InitializationCompleteCallbackContext *event)
+    {
+        if (event->error) {
+            printf("Error %u during the initialization\r\n", event->error);
+            return;
+        }
+        printf("Ble instance initialized\r\n");
+
+        Gap &gap = _ble_interface.gap();
+        ble_error_t error = gap.setAdvertisingPayload(make_advertising_data());
+        if (error) {
+            printf("Error %u during gap.setAdvertisingPayload\r\n", error);
+            return;
+        }
+
+        gap.setAdvertisingParams(make_advertising_params());
+
+        gap.onConnection(this, &BLEProcess::when_connection);
+        gap.onDisconnection(this, &BLEProcess::when_disconnection);
+
+        start_advertising();
+
+        if (_post_init_cb) {
+            _post_init_cb(_ble_interface, _event_queue);
+        }
+    }
+
+    /**
+     * Start the gatt client process when a connection event is received.
+     */
+    void when_connection(const Gap::ConnectionCallbackParams_t *connection_event)
+    {
+        printf("Connected.\r\n");
+    }
+
+    /**
+     * Stop the gatt client process when the device is disconnected then restart
+     * advertising.
+     */
+    void when_disconnection(const Gap::DisconnectionCallbackParams_t *event)
+    {
+        printf("Disconnected.\r\n");
+        start_advertising();
+    }
+
+    /**
+     * Setup the advertising parameters.
+     */
+    void setup_advertising()
+    {
+        Gap &gap = _ble_interface.gap();
+        gap.setAdvertisingPayload(make_advertising_data());
+        gap.setAdvertisingParams(make_advertising_params());
+    }
+
+    /**
+     * Start the advertising process; it ends when a device connects.
+     */
+    void start_advertising()
+    {
+        ble_error_t error = _ble_interface.gap().startAdvertising();
+        if (error) {
+            printf("Error %u during gap.startAdvertising.\r\n", error);
+        } else {
+            printf("Advertising started.\r\n");
+        }
+    }
+
+    /**
+     * Schedule processing of events from the BLE middleware in the event queue.
+     */
+    void schedule_ble_events(BLE::OnEventsToProcessCallbackContext *event)
+    {
+        _event_queue.call(mbed::callback(&event->ble, &BLE::processEvents));
+    }
+
+    /**
+     * Build data advertised by the BLE interface.
+     */
+    static GapAdvertisingData make_advertising_data(void)
+    {
+        static const uint8_t device_name[] = "GattClient";
+        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)
+        );
+
+        return advertising_data;
+    }
+
+    /**
+     * Build advertising parameters used by the BLE interface.
+     */
+    static GapAdvertisingParams make_advertising_params(void)
+    {
+        return GapAdvertisingParams(
+            /* type */ GapAdvertisingParams::ADV_CONNECTABLE_UNDIRECTED,
+            /* interval */ GapAdvertisingParams::MSEC_TO_ADVERTISEMENT_DURATION_UNITS(500),
+            /* timeout */ 0
+        );
+    }
+
+    events::EventQueue &_event_queue;
+    BLE &_ble_interface;
+    mbed::Callback<void(BLE&, events::EventQueue&)> _post_init_cb;
+};
+
+
+#endif /* GATT_EXAMPLE_BLE_PROCESS_H_ */

BLE_GattClient/README.md

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+# BLE Gatt Client example
+
+This application demonstrates detailed uses of the GattClient APIs. 
+
+When the application is started it advertises itself to its environment with the 
+device name `GattClient`. Once you have connected to the device with your mobile 
+phone, the application starts a discovery of the GATT server exposed by your 
+mobile phone. 
+
+After the discovery, this application reads the value of the characteristics 
+discovered and subscribes to the characteristics emitting notifications or 
+indications. 
+
+The device prints the value of any indication or notification received from the 
+mobile phone.
+
+# Running the application
+
+## Requirements
+
+You may use a generic BLE scanners:
+
+- [nRF Master Control Panel](https://play.google.com/store/apps/details?id=no.nordicsemi.android.mcp) for Android.
+
+- [LightBlue](https://itunes.apple.com/gb/app/lightblue-bluetooth-low-energy/id557428110?mt=8) for iPhone.
+
+Hardware requirements are in the [main readme](https://github.com/ARMmbed/mbed-os-example-ble/blob/master/README.md).
+
+## Building instructions
+
+Building instructions for all samples are in the [main readme](https://github.com/ARMmbed/mbed-os-example-ble/blob/master/README.md).
+
+