How to use QLowEnergyService::writeCharacteristic in different thread?

[swjqq]

How to solve this problem?

Here is my code:

class WriteCharacteristicThread : public QThread
{
    Q_OBJECT

public:
    WriteCharacteristicThread(QByteArray *buffer = nullptr, int packetSize = 244, int delayMs = 100, QLowEnergyService *service = nullptr, QString uuidStr = "")
    {
        m_service = service;
        if (m_service != nullptr)
        {
            m_characteristic = m_service->characteristic(QBluetoothUuid(uuidStr));
        }

        m_buffer = buffer;
        m_packetSize = packetSize;
        m_delayMs = delayMs;
    }

signals:
    void writeSizeChanged(int size);

protected:
    void run() override
    {
        if (!m_service || !m_characteristic.isValid() || !m_buffer || !m_buffer->size())
        {
            return;
        }

        QList<QByteArray> blocks;
        for (int i = 0; i < m_buffer->size(); i += m_packetSize)
        {
            blocks.append(m_buffer->mid(i, m_packetSize));
        }

        for (int i = 0; i < blocks.size(); i++)
        {
            m_service->writeCharacteristic(m_characteristic, blocks[i]);
            m_writeSize += blocks[i].size();
            emit writeSizeChanged(m_writeSize);

            msleep(m_delayMs);
        }
    }

private:
    QByteArray *m_buffer = nullptr;
    int m_packetSize = 244;
    QLowEnergyService *m_service = nullptr;
    QLowEnergyCharacteristic m_characteristic;
    int m_delayMs = 0;
    int m_writeSize = 0;
};

[Paul Colby]

Hi @swjqq,

I see nothing in your thread that's creating any QObject's with non-null parents, nor setting any child/parent relationships (they could be there, but I don't see it).

Have you tried stepping through the code with a debugger to see which line is causing the error?

Also, do you have any code connect'd to the WriteCharacteristicThread::writeSizeChanged() signal? If so, you might want to try using the Qt::QueuedConnection connection type explicitly.

Cheers.

[swjqq]

@Paul-Colby Thanks for your reply.

Have you tried stepping through the code with a debugger to see which line is causing the error?

This error occurs when the WriteCharacteristicThread::run() function executes.

Also, do you have any code connect'd to the WriteCharacteristicThread::writeSizeChanged() signal? If so, you might want to try using the Qt::QueuedConnection connection type explicitly.

[jsulm]

@swjqq Please post code as text, not pictures. m_service and m_characteristic are not allocated in your thread.