Diff: source/main.cpp

Revision:

0:7373a1c9d5b4

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/source/main.cpp	Thu Jan 14 11:25:30 2021 +0000
@@ -0,0 +1,181 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2019 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 "ble/BLE.h"
+#include "ble/Gap.h"
+#include "pretty_printer.h"
+
+const static char DEVICE_NAME[] = "BATTERY";
+
+using namespace std::literals::chrono_literals;
+
+static events::EventQueue event_queue(/* event count */ 16 * EVENTS_EVENT_SIZE);
+
+class BatteryDemo : ble::Gap::EventHandler {
+public:
+    BatteryDemo(BLE &ble, events::EventQueue &event_queue) :
+        _ble(ble),
+        _event_queue(event_queue),
+        _battery_level(50),
+        _adv_data_builder(_adv_buffer)
+    {
+    }
+
+    void start()
+    {
+        /* mbed will call on_init_complete when when ble is ready */
+        _ble.init(this, &BatteryDemo::on_init_complete);
+
+        /* this will never return */
+        _event_queue.dispatch_forever();
+    }
+
+private:
+    /** Callback triggered when the ble initialization process has finished */
+    void on_init_complete(BLE::InitializationCompleteCallbackContext *params)
+    {
+        if (params->error != BLE_ERROR_NONE) {
+            print_error(params->error, "Ble initialization failed.");
+            return;
+        }
+
+        print_mac_address();
+
+        start_advertising();
+    }
+
+    void start_advertising()
+    {
+        /* create advertising parameters and payload */
+
+        ble::AdvertisingParameters adv_parameters(
+            /* you cannot connect to this device, you can only read its advertising data,
+             * scannable means that the device has extra advertising data that the peer can receive if it
+             * "scans" it which means it is using active scanning (it sends a scan request) */
+            ble::advertising_type_t::SCANNABLE_UNDIRECTED,
+            ble::adv_interval_t(ble::millisecond_t(1000))
+        );
+
+        _adv_data_builder.setFlags();
+        _adv_data_builder.setName(DEVICE_NAME);
+
+        /* we add the battery level as part of the payload so it's visible to any device that scans */
+        _adv_data_builder.setServiceData(GattService::UUID_BATTERY_SERVICE, {&_battery_level, 1});
+
+        /* setup advertising */
+
+        ble_error_t error = _ble.gap().setAdvertisingParameters(
+            ble::LEGACY_ADVERTISING_HANDLE,
+            adv_parameters
+        );
+
+        if (error) {
+            print_error(error, "_ble.gap().setAdvertisingParameters() failed");
+            return;
+        }
+
+        error = _ble.gap().setAdvertisingPayload(
+            ble::LEGACY_ADVERTISING_HANDLE,
+            _adv_data_builder.getAdvertisingData()
+        );
+
+        if (error) {
+            print_error(error, "_ble.gap().setAdvertisingPayload() failed");
+            return;
+        }
+
+        /* when advertising you can optionally add extra data that is only sent
+         * if the central requests it by doing active scanning */
+        _adv_data_builder.clear();
+        const uint8_t _vendor_specific_data[4] = { 0xAD, 0xDE, 0xBE, 0xEF };
+        _adv_data_builder.setManufacturerSpecificData(_vendor_specific_data);
+
+        _ble.gap().setAdvertisingScanResponse(
+            ble::LEGACY_ADVERTISING_HANDLE,
+            _adv_data_builder.getAdvertisingData()
+        );
+
+        /* start advertising */
+
+        error = _ble.gap().startAdvertising(ble::LEGACY_ADVERTISING_HANDLE);
+
+        if (error) {
+            print_error(error, "_ble.gap().startAdvertising() failed");
+            return;
+        }
+
+        /* we simulate battery discharging by updating it every second */
+        _event_queue.call_every(
+            1000ms,
+            [this]() {
+                update_battery_level();
+            }
+        );
+    }
+
+    void update_battery_level()
+    {
+        if (_battery_level-- == 10) {
+            _battery_level = 100;
+        }
+
+        /* update the payload with the new value */
+        ble_error_t error = _adv_data_builder.setServiceData(GattService::UUID_BATTERY_SERVICE, make_Span(&_battery_level, 1));
+
+        if (error) {
+            print_error(error, "_adv_data_builder.setServiceData() failed");
+            return;
+        }
+
+        /* set the new payload, we don't need to stop advertising */
+        error = _ble.gap().setAdvertisingPayload(
+            ble::LEGACY_ADVERTISING_HANDLE,
+            _adv_data_builder.getAdvertisingData()
+        );
+
+        if (error) {
+            print_error(error, "_ble.gap().setAdvertisingPayload() failed");
+            return;
+        }
+    }
+
+private:
+    BLE &_ble;
+    events::EventQueue &_event_queue;
+
+    uint8_t _battery_level;
+
+    uint8_t _adv_buffer[ble::LEGACY_ADVERTISING_MAX_SIZE];
+    ble::AdvertisingDataBuilder _adv_data_builder;
+};
+
+/* Schedule processing of events from the BLE middleware in the event queue. */
+void schedule_ble_events(BLE::OnEventsToProcessCallbackContext *context)
+{
+    event_queue.call(Callback<void()>(&context->ble, &BLE::processEvents));
+}
+
+int main()
+{
+    BLE &ble = BLE::Instance();
+    ble.onEventsToProcess(schedule_ble_events);
+
+    BatteryDemo demo(ble, event_queue);
+    demo.start();
+
+    return 0;
+}