This example uses the Health Thermometer Profile to send thermometer information: The canonical source for this example lives at https://github.com/ARMmbed/mbed-os-example-ble/tree/master/BLE_Thermometer

Thermometer

This example uses the Health Thermometer Profile to send thermometer information:

  • Sensor location: thermometer placement on the body. The default value in this application is the ear (``LOCATION_EAR``). The characteristic description shows the other possible values.
  • Temperature: the initial temperature is 39.6, and it's incremented by 0.1 every half second. It resets to 39.6 when it reaches 43.0.

For more information see:

  • Temperature Type: GATT characteristic details for temperature type (sensor location).

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.

Hardware requirements are in the main readme.

Building instructions

Building with mbed CLI

If you'd like to use mbed CLI to build this, then you should refer to the main readme. The instructions here relate to using the developer.mbed.org Online Compiler

In order to build this example in the mbed Online Compiler, first import the example using the ‘Import’ button on the right hand side.

Next, select a platform to build for. This must either be a platform that supports BLE, for example the NRF51-DK, or one of the following:

List of platforms supporting Bluetooth Low Energy

Or you must also add a piece of hardware and the supporting library that includes a Bluetooth Low Energy driver for that hardware, for example the K64F or NUCLEO_F401RE with the X-NUCLEO-IDB05A1

List of components supporting Bluetooth Low Energy.

Once you have selected your platform, compile the example and drag and drop the resulting binary onto your board.

For general instructions on using the mbed Online Compiler, please see the mbed Handbook

Checking for success

Note: Screens captures depicted below show what is expected from this example if the scanner used is *nRF Master Control Panel* version 4.0.5. If you encounter any difficulties consider trying another scanner or another version of nRF Master Control Panel. Alternative scanners may require reference to their manuals.

  • Build the application and install it on your board as explained in the building instructions.
  • Open the BLE scanner on your phone.
  • Start a scan.

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-Thermometer/raw-file/a27dfda81620/img/start_scan.png

figure 1 How to start scan using nRF Master Control Panel 4.0.5

  • Find your device; it should be named *Therm*.

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-Thermometer/raw-file/a27dfda81620/img/scan_results.png

figure 2 Scan results using nRF Master Control Panel 4.0.5

  • Establish a connection with your device.

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-Thermometer/raw-file/a27dfda81620/img/connection.png

figure 3 How to establish a connection using Master Control Panel 4.0.5

  • Discover the services and the characteristics on the device. The *Health Thermometer* service has the UUID `0x1809` and includes the *Temperature Measurement* characteristic which has the UUID `0x2A1C`.

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-Thermometer/raw-file/a27dfda81620/img/discovery.png

figure 4 Representation of the Thermometer service using Master Control Panel 4.0.5

  • Register for the notifications sent by the *Temperature Measurement* characteristic.

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-Thermometer/raw-file/a27dfda81620/img/register_to_notifications.png

figure 5 How to register to notifications using Master Control Panel 4.0.5

  • You should see the temperature value change every half second. It begins at 39.6, goes up to 43.0 (in steps of 0.1), resets to 39.6 and so on.

https://developer.mbed.org/teams/mbed-os-examples/code/mbed-os-example-ble-Thermometer/raw-file/a27dfda81620/img/notifications.png

figure 6 Notifications view using Master Control Panel 4.0.5

source/main.cpp

Committer:
mbed_official
Date:
2019-09-19
Revision:
81:921892507e54
Parent:
79:16042006e938

File content as of revision 81:921892507e54:

/* 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"
#include "ble/services/HealthThermometerService.h"
#include "pretty_printer.h"

DigitalOut led1(LED1, 1);

const static char DEVICE_NAME[] = "Therm";

static events::EventQueue event_queue(/* event count */ 16 * EVENTS_EVENT_SIZE);

class ThermometerDemo : ble::Gap::EventHandler {
public:
    ThermometerDemo(BLE &ble, events::EventQueue &event_queue) :
        _ble(ble),
        _event_queue(event_queue),
        _sensor_event_id(0),
        _thermometer_uuid(GattService::UUID_HEALTH_THERMOMETER_SERVICE),
        _current_temperature(39.6f),
        _thermometer_service(NULL),
        _adv_data_builder(_adv_buffer) { }

    void start() {
        _ble.gap().setEventHandler(this);

        _ble.init(this, &ThermometerDemo::on_init_complete);

        _event_queue.call_every(500, this, &ThermometerDemo::blink);

        _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();

        /* Setup primary service. */
        _thermometer_service = new HealthThermometerService(_ble, _current_temperature, HealthThermometerService::LOCATION_EAR);

        start_advertising();
    }

    void start_advertising() {
        /* Create advertising parameters and payload */

        ble::AdvertisingParameters adv_parameters(
            ble::advertising_type_t::CONNECTABLE_UNDIRECTED,
            ble::adv_interval_t(ble::millisecond_t(1000))
        );

        _adv_data_builder.setFlags();
        _adv_data_builder.setLocalServiceList(mbed::make_Span(&_thermometer_uuid, 1));
        _adv_data_builder.setAppearance(ble::adv_data_appearance_t::THERMOMETER_EAR);
        _adv_data_builder.setName(DEVICE_NAME);

        /* 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;
        }

        /* Start advertising */

        error = _ble.gap().startAdvertising(ble::LEGACY_ADVERTISING_HANDLE);

        if (error) {
            print_error(error, "_ble.gap().startAdvertising() failed");
            return;
        }
    }

    void update_sensor_value() {
        _current_temperature = (_current_temperature + 0.1f > 43.0f) ? 39.6f : _current_temperature + 0.1f;
        _thermometer_service->updateTemperature(_current_temperature);
    }

    void blink(void) {
        led1 = !led1;
    }

private:
    /* Event handler */

    virtual void onDisconnectionComplete(const ble::DisconnectionCompleteEvent&) {
        _event_queue.cancel(_sensor_event_id);
        _ble.gap().startAdvertising(ble::LEGACY_ADVERTISING_HANDLE);
    }

    virtual void onConnectionComplete(const ble::ConnectionCompleteEvent &event) {
        if (event.getStatus() == BLE_ERROR_NONE) {
            _sensor_event_id = _event_queue.call_every(1000, this, &ThermometerDemo::update_sensor_value);
        }
    }

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

    int _sensor_event_id;

    UUID _thermometer_uuid;

    float _current_temperature;
    HealthThermometerService *_thermometer_service;

    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);

    ThermometerDemo demo(ble, event_queue);
    demo.start();

    return 0;
}