Reading data from Serial Port is extremely slow

serkan_tr

On the QT C++ side, I want to transfer the potentiometer data I got from Arduino to the slider on the screen. but 3-5 minutes after moving the potentiometer, the slider starts to move this is a huge delay codes i think it's an error in the code part:
arduino Code:

void setup() {
  Serial.begin(115200);
}
void loop(){
void loop() {
  uint8_t data = map(analogRead(A0),0,1023,0,255);
  Serial.write(data);
}

QT C++ code

joy = std::thread{std::bind(&MainWindow::setRxData, this)};
.
.
bool MainWindow::rxData(){
        while(true){
            if(serial_.waitForReadyRead(10)){
                uint8_t value;
                quint64 size = serial_.read((char*)&value, sizeof(value));
                qDebug() << "Read" << value << "bytes:";
                data_ch[0] =  value;
                sliderChange();
}}}

void MainWindow::sliderChange(){
    ui->slider_1->setValue(data_ch[0]);
}

JonB

@serkan_tr
Does it make any difference if you do not create a separate thread and use waitForReadyRead() but rather just use Qt's asynchronous serial calls instead?

serkan_tr

@JonB I do not fully understand

JonB

@serkan_tr
I do not know why you use std::thread, a while(true) loop and waitForReadyRead(). I suggested you try with Qt's QSerialPort asynchronous signals/slots and no separate thread to see whether that affected performance. I do not know whether that is an issue.

Furthermore (all related to your thread usage): do I understand that your MainWindow::rxData() runs in some other thread? But it calls ui->slider_1->setValue(), it is forbidden in Qt to access the main UI widgets from any other thread....

serkan_tr

@JonB
Thank you