I am having trouble trying to get my program to continually send the string "move 200"
while I hold down a button. I have the button set to auto repeat however it only sends once the button is released not while it is holding down. However while being held down the counter is adding how many times the message should have been sent. I am at a lost.
mainwindow.cpp
void MainWindow::on_forwardButton_clicked()
{
if(arduino->isWritable()){
arduino->write(command.toStdString().c_str());
qDebug() << i;
}else{
qDebug() << "Couldn't write to serial!";
}
ui->label->setText("Moving");
i++;
}
mainwindow.h
ifndef MAINWINDOW_H
define MAINWINDOW_H
include <QMainWindow>
include <QDialog>
include <QSerialPort>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private slots:
void on_forwardButton_clicked();
private:
Ui::MainWindow *ui;
QSerialPort *arduino; //makes arduino a pointer to the SerialPort
bool arduino_is_available;
QString command = "move 200";
bool buttonReleased = false;
};
endif // MAINWINDOW_H
Code added following @dtech suggestion
pButtonTimer = new QTimer;
connect(pButtonTimer, SIGNAL(timeout()), this, SLOT(sendData()));
int i = 0;
void MainWindow::on_forwardButton_pressed()
{
pButtonTimer->start(1000);
ui->label->setText("Moving");
qDebug() << "Button Pushed";
}
void MainWindow::on_forwardButton_released()
{
pButtonTimer->stop();
}
void MainWindow::sendData(){
i++; //used to count how many times the command should have been sent
qDebug() << i << "sendData is running"; //notifies me the function has been called
if(arduino->isWritable()){
arduino->write(command.toStdString().c_str());
qDebug() << i << "arduino is writable with command " << command; //lets me know the Arduino is writable
}
else{qDebug() << "Couldn't write to serial!";}
}
After releasing the button the serial monitor in the Arduino then shows everything sent and the robot moves
I suggest you expand on your design somewhat:
QTimer
with an interval depending on the rate you want to send the string at, and the timer to the function that sends the stringEvents are sent only once, thus the handlers will be executed only once, if you want to keep on repeating it, you will have to use a timer or some other event driven way. You cannot use a loop as that would block the GUI thread and your application will stop responding.
Sure, you could use the button's auto repeat, and there is the option to adjust the triggering and repeating intervals, but a solution that puts a line between logic and GUI is better. You should really rely on the GUI for storing data or controlling the internal logic. The GUI should only be a front end.
You need more work on the serial port though. If you are going to use it from the GUI thread, you will have to use the non-blocking API. Which will require to extend on your implementation a little bit more. There is a good example on how to achieve that, you only need to modify it to simply enable the sending of further payloads once the previous payload has been successfully sent. In pseudo code:
on button press
start timer
on button release
stop timer
onTimeout
if (can send)
send
can send = false
onBytesWritten
accumulate bytes
if (payload is completed)
can send = true
reset payload byte counter
Of course, you will also have to do some error checking, you can't just expect it to work. The example linked contains basic error handling.