QList<DataArray> channelsData;

    // `data` contains i th channels data

    void addChannelData(unsigned int channel, DataArray data);

    Zoomer* zoomer;

    NumberFormat numberFormat;

    unsigned int sampleSize; // number of bytes in the selected number format

    double (MainWindow::*readSample)();

    // note that serialPort should already have enough bytes present

    void onNumOfChannelsChanged(int value);

    void onNumberFormatButtonToggled(int numberFormatId, bool checked);

    void selectNumberFormat(NumberFormat numberFormatId);

    void clearPlot();

    void spsTimerTimeout();

    void demoTimerTimeout();

    void enableDemo(bool enabled);