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USB Communication Using Qt

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  • Z Offline
    Z Offline
    ZapB
    wrote on last edited by
    #11

    On windows you refer to serial devices as \.\COM1, \.\COM2 etc. Which in C++ translates to

    @
    "\\.\COM1"
    @

    when you escape all those backslashes.

    Nokia Certified Qt Specialist
    Interested in hearing about Qt related work

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    • K Offline
      K Offline
      koahnig
      wrote on last edited by
      #12

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

      Vote the answer(s) that helped you to solve your issue(s)

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      • A Offline
        A Offline
        andre
        wrote on last edited by
        #13

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

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        • Z Offline
          Z Offline
          ZapB
          wrote on last edited by
          #14

          /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.

          Nokia Certified Qt Specialist
          Interested in hearing about Qt related work

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          • K Offline
            K Offline
            koahnig
            wrote on last edited by
            #15

            [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

            Vote the answer(s) that helped you to solve your issue(s)

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            • A Offline
              A Offline
              andre
              wrote on last edited by
              #16

              [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/

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              • K Offline
                K Offline
                koahnig
                wrote on last edited by
                #17

                [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.

                Vote the answer(s) that helped you to solve your issue(s)

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                • Z Offline
                  Z Offline
                  ZapB
                  wrote on last edited by
                  #18

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

                  Nokia Certified Qt Specialist
                  Interested in hearing about Qt related work

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                  • A Offline
                    A Offline
                    andre
                    wrote on last edited by
                    #19

                    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...

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                    • Z Offline
                      Z Offline
                      ZapB
                      wrote on last edited by
                      #20

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

                      Nokia Certified Qt Specialist
                      Interested in hearing about Qt related work

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                      • K Offline
                        K Offline
                        koahnig
                        wrote on last edited by
                        #21

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

                        Vote the answer(s) that helped you to solve your issue(s)

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                        • C Offline
                          C Offline
                          Candiman
                          wrote on last edited by
                          #22

                          @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.

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                          • Z Offline
                            Z Offline
                            ZapB
                            wrote on last edited by
                            #23

                            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.

                            Nokia Certified Qt Specialist
                            Interested in hearing about Qt related work

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                            • K Offline
                              K Offline
                              koahnig
                              wrote on last edited by
                              #24

                              @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.

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                              • AlicemirrorA Offline
                                AlicemirrorA Offline
                                Alicemirror
                                wrote on last edited by
                                #25

                                @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.

                                Enrico Miglino (aka Alicemirror)
                                Balearic Dynamics
                                Islas Baleares, Ibiza (Spain)
                                www.balearicdynamics.com

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                                • C Offline
                                  C Offline
                                  Candiman
                                  wrote on last edited by
                                  #26

                                  Great. Tnx Alicemirror.

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                                  • D Offline
                                    D Offline
                                    dan_geo
                                    wrote on last edited by
                                    #27

                                    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.

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                                    • C Offline
                                      C Offline
                                      Candiman
                                      wrote on last edited by
                                      #28

                                      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!

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                                      • D Offline
                                        D Offline
                                        dan_geo
                                        wrote on last edited by
                                        #29

                                        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.

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                                        • D Offline
                                          D Offline
                                          dcbasso
                                          wrote on last edited by
                                          #30

                                          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.

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