Bluetooth Low Energy

Hello ........

I am writing some logging software running on raspberry pi using QT. I have successfully interfaced with all the sensors using a wired serial port and a standard bluetooth to serial device (HC-05) . The sensors all output text data via a serial port.

I now want to use a blue tooth low energy device, the module I am using is the BT4.0 HM-10, which acts a pass through device for the serial text data.


I have been partially successful in using the heartlistener code as a reference, however, as soon as I

Code:

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m_control->connectToDevice();

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I start to receive the following output in the console:

qt.bluetooth.bluez: cannot find matching characteristic for notification/indication

This is before I

Code:

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m_control->discoverServices();

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After doing service discovery and using a slot to catch characteristic changed signal I am able to output the line of text from the custom service of the HM-10 module BUT this happens even before I enable change notifications for the characteristic. i.e. if I take the code out from this function I still get notifications:

Code:

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void leConnection::serviceStateChanged(QLowEnergyService::ServiceState s)

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I should add all this code is being run on ubuntu and not the raspberry pi, for which I use a cross complier when I have the final code.


I have tried disabling notifications but I still get change notifications processed by:

Code:

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void leConnection::updateSerialValue(const QLowEnergyCharacteristic &c, const QByteArray &value)

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Any help or tips much appreciated.


Paul





Full code:

Code:

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#include "leconnection.h"
 
 leConnection::leConnection()
{
 
  // connect(m_deviceDiscoveryAgent, SIGNAL(finished()), this, SLOT(scanFinished()));
 
   hm10Name = "MainStart"; //HMSoft
 
   hm10Address = "A4:D5:78:69:C0:AF"; //A4:D5:78:69:C0:AF
 
   hm10ServiceId = "0000FFE0-0000-1000-8000-00805F9B34FB";
 
   ptrHM10serial = new QBluetoothUuid(hm10ServiceId);
 
   hm10CharId    = "0000FFE1-0000-1000-8000-00805F9B34FB";
 
   ptrHM10Char = new QBluetoothUuid(hm10CharId);
 
 
 
   ptrQBluetoothDeviceInfo = new QBluetoothDeviceInfo(QBluetoothAddress(hm10Address),hm10Name,0);
 
   qDebug() << "created ptrQBluetoothDeviceInfo Object :) ";
 
   m_control = new QLowEnergyController(*ptrQBluetoothDeviceInfo, this);
 
   m_control->connectToDevice();
 
   m_service=0;
 
 
  connect(m_control, SIGNAL(connected()),
           this, SLOT(deviceConnected()));
 
   connect(m_control, SIGNAL(error(QLowEnergyController::Error)),
           this, SLOT(controllerError(QLowEnergyController::Error)));
 
 
   connect(m_control, SIGNAL(serviceDiscovered(QBluetoothUuid)),
           this, SLOT(serviceDiscovered(QBluetoothUuid)));
 
 
   connect(m_control, SIGNAL(discoveryFinished()),
           this, SLOT(serviceScanDone()));
 
 
   connect(m_control, SIGNAL(disconnected()),
           this, SLOT(deviceDisconnected()));
 
  }
 
 
  void leConnection::deviceConnected()
  {
      qDebug() << "Success Device Connected .......  " << ptrQBluetoothDeviceInfo->name();
 
      m_control->discoverServices();
 
  }
 
  void leConnection::controllerError(QLowEnergyController::Error error)
  {
      qDebug() << "Cannot connect to remote device.";
 
      qDebug() << "Controller Error:" << error;
  }
 
 
  void leConnection::serviceDiscovered(const QBluetoothUuid &gatt)
 
  {
      qDebug()  << "service"   << gatt.toString();
 
  }
 
 
 
void leConnection::connectToService(const QString &address)
 
{
 
 
}
 
 
void leConnection::serviceScanDone()
{
 
 
   qDebug() << "Services Scan Done for ..... "   << ptrHM10serial->toString();
 
 
   m_service = m_control->createServiceObject(*ptrHM10serial,this);
 
   m_service->discoverDetails();
 
 
   connect(m_service, SIGNAL(characteristicChanged(QLowEnergyCharacteristic,QByteArray)),
                  this, SLOT(updateSerialValue(QLowEnergyCharacteristic,QByteArray)));
 
 
   connect(m_service, SIGNAL(stateChanged(QLowEnergyService::ServiceState)),
                  this, SLOT(serviceStateChanged(QLowEnergyService::ServiceState)));
 
 
   connect(m_service, SIGNAL(descriptorWritten(QLowEnergyDescriptor,QByteArray)),
                  this, SLOT(confirmedDescriptorWrite(QLowEnergyDescriptor,QByteArray)));
}
 
 
void leConnection::serviceStateChanged(QLowEnergyService::ServiceState s)
 
{
 
   qDebug() <<  "gets to here 4 "  << s;
 
    switch (s) {
 
    case QLowEnergyService::ServiceDiscovered:
 
    {
 
 
        const QLowEnergyCharacteristic hm10Char = m_service->characteristic(*ptrHM10Char);
 
 
         qDebug() <<  hm10Char.value() << "lllllllll";
 
 
         const QLowEnergyDescriptor m_notificationDesc =
 
                                    hm10Char.descriptor(QBluetoothUuid::ClientCharacteristicConfiguration);
 
               if (m_notificationDesc.isValid())
 
              {
                   qDebug() <<  "gets to here 4yyyyyyyyyyyyyyyyyyy ";
 
                   m_service->writeDescriptor(m_notificationDesc, QByteArray::fromHex("0100"));
 
              }
 
     break;
 
 
    }
    default:
 
        //nothing for now
        break;
    }
 
}
 
 
 
void leConnection::updateSerialValue(const QLowEnergyCharacteristic &c, const QByteArray &value)
 
 
{
 
    qDebug() << c.uuid();
 
 
    qDebug() << value;                                                      // part victron line
 
}
 
 
 
 
void leConnection::confirmedDescriptorWrite(const QLowEnergyDescriptor &d, const QByteArray &value)
{
 
    qDebug() <<  "gets to here 6 "  <<  value ;
 
    if (value == QByteArray("0100"))
    {
        qDebug()  << " testing";
    }
 
 
    if (d.isValid() && d == m_notificationDesc && value == QByteArray("0000"))
 
    {
        //disabled notifications -> assume disconnect intent
 
        m_control->disconnectFromDevice();
 
        delete m_service;
 
        m_service = 0;
    }
 
}
 
 
 
void leConnection::deviceDisconnected()
{
 
    qDebug() << "Remote device disconnected";
}
 
 
leConnection::~leConnection()
{
 
}

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