USB Communication Using Qt

[koahnig]

Thanks ZapB
However, the serial com part is easy.
How does
@
"/dev/ttyUSB0"
@
translate on a windows system?
Is it
@"\\.\USB0"@ ?

[andre]

Could you not use QExtSerialPort to simply list the available ports, instead of guessing their names?

[ZapB]

/dev/ttyUSB0 is simply the name that the kernel (or udev or whatever else you are using) assigns to serial over USB devices ie when using a usb-serial convertor. So when using this type of device under windows the corresponding device is COM1.

If you are not using a usb-serial convertor then you have to use the libusb functionality for communicating - that is you cannot simply use COM1 etc.

[koahnig]

[quote author="Andre" date="1303983404"]Could you not use QExtSerialPort to simply list the available ports, instead of guessing their names?[/quote]

Not that I am aware off. Probably, you have to do it brute force by checking all com ports.

[quote author="ZapB" date="1303983794"]If you are not using a usb-serial convertor then you have to use the libusb functionality for communicating - that is you cannot simply use COM1 etc.[/quote]

That gives me something to chew on...

Thanks for your valuable responses

[andre]

[quote author="koahnig" date="1303984402"]
[quote author="Andre" date="1303983404"]Could you not use QExtSerialPort to simply list the available ports, instead of guessing their names?[/quote]

Not that I am aware off. Probably, you have to do it brute force by checking all com ports.

[/quote]

There is an enumerator in the source code: http://qextserialport.cvs.sourceforge.net/viewvc/qextserialport/qextserialport/

[koahnig]

[quote author="Andre" date="1303985184"]
There is an enumerator in the source code: http://qextserialport.cvs.sourceforge.net/viewvc/qextserialport/qextserialport/
[/quote]

you mean the enum on NamingConvention ?
I did not come across this yet. But it is nowherelse referenced. So it could be dead source.

[ZapB]

No, there is a device enumeration function in qextserialport that probes what serial devices you have available.

[andre]

I mean this class: http://qextserialport.cvs.sourceforge.net/viewvc/qextserialport/qextserialport/qextserialenumerator.h?revision=1.3&view=markup

Sure, old code, and not in the docs, but the code is there...

[ZapB]

BTW the sourceforge project is no longer active. The new home is "here":http://code.google.com/p/qextserialport/

[koahnig]

Got it!
Thanks again. Will try to use it. Apperently, it was not part of the example I have come across.

[Candiman]

@Koahnig, if I don't come right with libusb I can fall back on serial to USB as you suggested. Tnx for the link to qextserport.
@ZapB, tnx for the info serial to USB converter chip. If required I will modify my hardware and go the serial route.
I will post here again on completion of the project with info on how to do it for others that might find it useful.

[ZapB]

OK. For info, the QStateMachine framework can be very handy for controlling hardware devices so it may be worth a look in you case. Good luck with your project.

[koahnig]

@Candiman Thx for feedback. Good to know that it helped. Good luck with your project. Please make sure to post a link in this thread. I am interested to see the outcome.
@ZapB Thx for updated link. Wasn't aware of this. There seem to be a couple of derivatives of the source floating around. Actually I started out with one, but some things required reversal. So it is good to know where the original source code is. Have fun.

[Alicemirror]

@all

Hi, I have found this thread because I have a similar problem.

I have to communicate with a serial external device folowing a simple yet precise protocol. I have tried a fast test to develop the protocol using RXTCComm java library that works not so good and now I was searching for a Qt approach that is the final goal of the other side of the device.

I try to put all your advices together and see if a working stuff can be done. If it maybe useful I put the project on the project area so who is interested can follow. As the project is ready and setup it will be on projects.forum.nokia.com/mill-machine I will announce it on t the forum appropriate area and in the Qt embedded group.

Cheers.

Anticipating many thanks to all.

[Candiman]

Great. Tnx Alicemirror.

[dan_geo]

Hi. I have used rs232 communication in visual c++ 6.0
which work very well. But because of my problem with
transmit images trough socket in VC++ which is
too complicated than Qt implementation ( very simple ).
I need to implement rs232 comunication.
My interface have to use TCP socket for internet comunication and rs232 for comunicate with microcontroller
and electrical devices.

[Candiman]

Hi dan_geo, let me know if you get your RS232 comms working with Qt. I have had to shift focus to a different project but during the downtime over the December holidays and from Jan 2012 I will be putting effort into the USB via Qt project again since many of my projects can benefit from having a GUI that I can design with Qt. I decided not to go with the RS232 option because so many PCs these days don't have a serial port. USB to serial converters are cheap, but if I can communicate directly with my device using USB then I don't need any additional hardware / drivers etc.
Good luck!

[dan_geo]

I have not get rs232 comm. Next days i will try to
implement them in Qt. If you are a source, please
sent to me. About usb, this task i will do later
with PIC18F4455. At usb i understand that
for make a host usb is more complicated than
implement a usb client for example a controller.

[dcbasso]

What its the best to access USB port:

http://doc.qt.nokia.com/qtextended4.4/qserialport.html

http://code.google.com/p/qextserialport/

http://qt-apps.org/content/show.php/QSerialDevice?content=112039 (Updated)

Thanks.

[koahnig]

According to "this post":http://qt-project.org/forums/viewthread/15580/#90074 there is a wiki on "QtSerialPort":http://qt-project.org/wiki/QtSerialPort Apparently, the source is inherited from QSerialDevice.