App for bluetooth scanning

[SGaist]

Hi,

Are you reimplementing an equivalent to Apple's HomeKit ?

[Anonymous_Banned275]

@SGaist said in App for bluetooth scanning:

Apple's HomeKit

I am currently working on similar project - controlling a radio transceiver.
I am basically replacing "wired control" with wireless - bluetooth.
The key is - the controlled device - "the box" - has to be enabled to allow such control. In my case the control is limited by design. I can "set the frequency", but I cannot "key the transmitter" .
You could call that "device security".
AT present the box is expecting plain serial communication commands , pretty much "modem style". These commands could be encoded to provide for additional bluetooth security .
Is that what you are referring to as "security"?'' It would probably be interesting to code , but given limited range of bluetooth and me controlling only single bluetooth device , I would consider that little of overkill .

BUT - be aware that Qt / Linux implementation of bluetooth has a MAJOR issue - there is no option to scan / inquiry for physically present devices only.
There is a database of past devices and I have not found Qt/Linux way to delete non-existent devices from such database. .
I had to go back to HCI to clear this database.

[AndreaFurlani]

Thank you both for the replies.
@SGaist Yes I'm working on something similar.

@AnneRanch as security I mean something like "you cannot see information of the devices or a devices list on an external app because Bluetooth doesn't allow thing like this"

I was thinking something like this:

1. The app scan for devices to connect and I can choose the box (easy part, lot of examples in Qt);
2. Once connected, the box send to the app a list of all the actually connected devices which will be displayed in the app;
3. In the app I can select a device and a new window will appears with the buttons "on" and "off";
4. Once I select one of the options, the app will send to the box a signal "device x, command y";
5. The box reads the command and send it to the device that will perform the designated action

[SGaist]

Thanks for the clear picture.

Can you explain what you were thinking to do with regards to the use of signals ?

It seems that you have a pretty well defined API so I think you'll have a controller that will be responsible for the communication with the "hub" device. Is it so ?

[Anonymous_Banned275]

@AndreaFurlani said in App for bluetooth scanning:

The app scan for devices to connect and I can choose the box (easy part, lot of examples in Qt);
I am not sure what you call "the box" .
I do not want to be pedantic - but IMHO "home brew " terminology can became unnecessary issue in the long run.
During my , still ongoing , development I found that it is helpful to call "local (bluetooth) device " the one connected to your controller and "remote (bluetooth) device ".
I have found that "client /server" is little misleading when "two way communication" is involved , so does "home ".

Again - not that important when it is all "under one roof " .

I am not sure that monitoring the bluetooth "raw data" is best way to limit the function of the "remote device". But I came from "telecommunication background " and I always view the communication payload as "transparent ". In my case - I cannot "key-up" the remote transmitter device so I won't even attempt to send anything close to such command.

[AndreaFurlani]

@SGaist Since I'm quite new in Qt and specially in bluetooth, I have no idea on how my app can ask to the box for the list of devices, so my idea was like:

1- the app send a request signal to the box
2- the box answer back by sending a list containing all the devices connected
3- once the user has selected what to do with a device, the app send back a variable containing the device and the action to perform

[Anonymous_Banned275]

@AndreaFurlani said in App for bluetooth scanning:

@SGaist Since I'm quite new in Qt and specially in bluetooth, I have no idea on how my app can ask to the box for the list of devices, so my idea was like:

1- the app send a request signal to the box
2- the box answer back by sending a list containing all the devices connected
3- once the user has selected what to do with a device, the app send back a variable containing the device and the action to perform

OK, I am still missing something here .
Again , from my background :
in general - "communication" has three basic parts and for simplicity it is defined as communication in one direction only.

sender -> communication media ->receiver
or
source communication media sink / load

Where is your "box" in this scheme ? Does look like this ?

sender communication media (bluetooth) "receiver BOX sender " communication media ( actual media ?) receiver

where "BOX sender" is actually multiple senders ?

[SGaist]

Your box needs to have a protocol established.

See the exchanging data between devices part of the Bluetooth chapter in Qt's documentation.

You'll then have to establish a clear protocol for your "service".

[Anonymous_Banned275]

@SGaist said in App for bluetooth scanning:

Your box needs to have a protocol established.

See the exchanging data between devices part of the Bluetooth chapter in Qt's documentation.

You'll then have to establish a clear protocol for your "service".

Very helpful post .
Since I started by using btscanner example I was wondering why my "remote bluetooth device " is "identified as "SPP" . Now I have an answer.
After I get this "inquiry" mess cleaned - up my next step is indeed using "chat "...

[AndreaFurlani]

@SGaist Thank you very much. I'll try to read it and make some tries.

[AndreaFurlani]

Hello again, I returned Here since I'm still stuck. In this moment I'm trying to create a new bluetooth service (in the box code), where I'll ask for creating an retrieve a list of all connected devices (and I still have not idea on how to do it, I saw this in the documentation, maybe could be useful).
So in this way I can create another service (on the app code) where once retrieved the list will associate to a device a command (and again I still have not idea on how to do it) and send it back to the box to execute it.
Any idea on how I can do it?
Thank you again for all the help.

[SGaist]

Something is not clear, what will run on that box ?

[Anonymous_Banned275]

@AndreaFurlani I would suggest to take a look at examples. Start with "qtconnectivity" - btscanner.
It does the basics - scans for nearby bluetooth devices etc.
However it is scarcely documented - in code - and assumes some knowledge about bluetooth.
From my experience - do not assume that your "local bluetooth device " is enabled to be used to scan for "remote bluetooth devices".
I have two with different dongles with different "class of service" and the scan results are NOT the same.

Same for "remote bluetooth device" - my powered "remote device " with serial USB to bluetooth adapter" can be "found" , my powered remote "boom box" has to be activated to be found.
Beware of running active operating system "bluetooth manager" software - it actually over-rides , takes precedence, of SOME of your code.

[AndreaFurlani]

@SGaist The box is connected to some lights and sensors via zigbee or bluetooth. I need a list of all the connected devices to the box

[AndreaFurlani]

@AnneRanch thank you for the answer. I already watched all the bluetooth examples in Qt creator but no one of them is useful to understand how to create a new service and in particular how to do the things I need.

[Anonymous_Banned275]

@AndreaFurlani said in App for bluetooth scanning:

how to create a new service

Since bluetooth devices have "class of service" be careful using the term.
I am still unclear about your overall task . I think I asked for simple hardware picture before .
Let me make analogy with my project
local bt device (PC) -> bluetooth media communication path -> remote bt device (radio )

one on my "services" would be - set the radio frequency

so "my box - radio " would turn on correct frequency and display it on build-in LCD

Are you attempting to do similar tasks via your box ?

[SGaist]

@AndreaFurlani said in App for bluetooth scanning:

@SGaist The box is connected to some lights and sensors via zigbee or bluetooth. I need a list of all the connected devices to the box

Hence my question what software runs on that box ?

[AndreaFurlani]

Hello I'm back again. I made some progress in writing my code. Now the box starts the advertising without problem.
Here's the code:

void bluetoothDevice::start(bool debugMode, bool protocolDebug)
{
    //Personalized Service for connected bluetooth devices list

    static const QLatin1String serviceUuid("11223344-5566-7788-99aa-bbccddeeff00");
    //static const QLatin1String writeListUuid("11223344-5566-7788-99aa-bbccddeeff11");
    static const QLatin1String readListUuid("11223344-5566-7788-99aa-bbccddeeff11");

    // [Advertising Data]
        QLowEnergyAdvertisingData advertisingData;
        advertisingData.setDiscoverability(QLowEnergyAdvertisingData::DiscoverabilityGeneral);
        advertisingData.setIncludePowerLevel(true);
        advertisingData.setLocalName("BOX");
        advertisingData.setServices(QList<QBluetoothUuid>() << QBluetoothUuid(serviceUuid));

    // [Service Data]
        QLowEnergyCharacteristicData readList;

        readList.setUuid(QBluetoothUuid(readListUuid));
        readList.setProperties(QLowEnergyCharacteristic::Read);
        const QLowEnergyDescriptorData clientConfig(QBluetoothUuid::CharacteristicUserDescription,QByteArray(2, 0));
        readList.addDescriptor(clientConfig);


        //writeList.setUuid(QBluetoothUuid(writeListUuid));
        //writeList.setProperties(QLowEnergyCharacteristic::Write);


        QLowEnergyServiceData serviceData;
        serviceData.setType(QLowEnergyServiceData::ServiceTypePrimary);
        serviceData.setUuid(QBluetoothUuid(serviceUuid));
        serviceData.addCharacteristic(readList);
        //serviceData.addCharacteristic(writeList);


    // [Start Advertising]

        leController.reset(QLowEnergyController::createPeripheral());
        service_list.reset(leController->addService(serviceData));
        leController->startAdvertising(QLowEnergyAdvertisingParameters(), advertisingData,advertisingData);


    qCDebug(BLELog) << " Start BLE backend [...] ";

    ConnectionHandler connectionHandler;
    DeviceHandler m_deviceHandler;


    // TODO! Restore debug options.
    GenericDeviceIf::start(debugMode, protocolDebug);

    // Initialize reachable state to unreachable.
    DataModel::getInstance()->setDeviceCategoryReachable(_category, false);

    _endpoints = DataModel::getInstance() ->getEndpointsListByCategory(dataBaseClasses::ENDPOINT_CATEGORY_BLE);

    m_deviceHandler.setDevice(nullptr);
    qDeleteAll(devices);
    devices.clear();

    emit devicesChanged();

    qCDebug(BLELog) << "Scanning for devices...";

    discoveryAgent->start(QBluetoothDeviceDiscoveryAgent::LowEnergyMethod);

    emit scanningChanged();

    // [Retrieving the list of devices]

        characteristic = service_list->characteristic(QBluetoothUuid(readListUuid));

        for (const auto &e: _endpoints){
            L.append(QString(e->getMapping()).toUtf8());
        }

        if (L.empty())
            qCDebug(BLELog) << "No endpoints loaded in the list";

        for (const auto &list: L) {
            service_list -> writeCharacteristic(characteristic, list) ;
        }


}

In this way I am able to connect to the BOX using an external BLE scanner app on my phone and once connected I would like to see the content of "list".
With this code the problem is that I can see only the last MAC address in the list, how can I see the complete content?

[Habanvee]

I have been using Bluetooth LE Explorer.
But my Bluetooth is not turning on on windows 10 for 2 days any help.

Updated: Glad found the solution here for Bluetooth turning on issue.

[jsulm]

@Habanvee In what way is your question related to Qt?
You should rather ask in a Windows forum.