USB to Serial Converter

Discussion in 'Embedded Systems and Microcontrollers' started by Sparky49, Sep 17, 2013.

  1. Sparky49

    Thread Starter Active Member

    Jul 16, 2011
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    Hi all,

    I've recently got a new laptop, which is great, but unfortunately it comes with no serial port. I have a dev kit for the HCS12, which is also really great, but alas it connects only via serial.

    I have looked on Amazon, and have found several USB to serial converters, eg:

    http://www.amazon.co.uk/ABC-Product...&qid=1379434843&sr=8-1&keywords=usb+to+serial

    However, I was wondering if using the USB port would make Codewarrior a bit confused.

    Has anyone got any experience and/or thoughts on the matter? Can I compile and debug as usual, or will I have to go through some different procedure?

    Many thanks,

    Sparky
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,498
    2,364
    The main issue with USB to RS232 is how it handles the Hardware Handshake lines.
    There is only two communication lines on the USB, so it all depends on what the method at equip. at the end uses, if it uses XON/XOFF (S/W handshake) then it should be no problem.
    Or even if the RS232 Plug has them jumpered across.
    Max.
     
  3. Brownout

    Well-Known Member

    Jan 10, 2012
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    My homebrew serial programs don't work with USB-serial because I don't see the addresses allocated to the 'virtual' ports, and thus cannot program them into my code. I've never found a good solution, but I'm going to try the FT4232 demo board, which hosts the FTDI4232 chip. I'm a little more interested in the PIO features of the system, so I'll try those first.
     
  4. t06afre

    AAC Fanatic!

    May 11, 2009
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    I am sure you know somebody that has one or several you can use for testing. Hard to say yes or no. They often work nice then connected to a proper serial port. But then used as in say some simple PIC programmers they can be dodgy
     
  5. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    A good solution is to change the com port number in the device manager.
     
  6. Brownout

    Well-Known Member

    Jan 10, 2012
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    What does that do for me?
     
  7. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    I guess I misread your post, why would you need to know the address of the port? You need to open the port by its name, that is if you are using windows.
     
  8. Brownout

    Well-Known Member

    Jan 10, 2012
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    A protected OS won't allow that. I use inpout32 to get access to the machine ports at the kernal level. That requires I know that hardware address of the registers I want to write and read. If you know a better way, them I'm all ears.
     
  9. panic mode

    Senior Member

    Oct 10, 2011
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    what software you use there? I use mostly MS products (anything from VB6, C#, VB.NET etc.) and have no problems accessing serial port on any windows platform. don't care about addresses, just open port by name (such as COM1) after setting properties (baud rate, data bits, stop bits, handshaking, parity). it's rather trivial.
     
    kubeek likes this.
  10. Brownout

    Well-Known Member

    Jan 10, 2012
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    Ok, maybe I'm getting myself confused between serial port programs and other programs I've written using the printer port to emulate serial protocols other than standard UART. I have programs to emulate IEEE 1149 (JTAG) for hardware testing. I had to find a way to get around windows protection of the printer port. This page describes the problem and solution http://logix4u.net/parallel-port/16-inpout32dll-for-windows-982000ntxp I always assumed using the serial port would require a similar solution.

    Also, I didn't read the question correctly and didn't give much of a useful response. My apologies to the OP.
     
  11. panic mode

    Senior Member

    Oct 10, 2011
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    I've seen some commotion here and there about accessing LPT ports under protected OSs (NT based versions of Windows). from what I gather, it is the direct access to ports that some people are used to since DOS days (which was easy, but times have changed). i did not use LPT in a very long time but i imagine accessing it today would be same as using serial ports - no point in fighting the OS (i guess i will know when i try).

    in response to Sparky:
    i have bunch of USB-RS232 converters (more than 10). i use them all the time and as some get installed or deployed, i keep buying new ones. most work just fine, problem is with few that don't. for example i had some lemons from Ultra. they had included drives for all popular OSs and worked initially under XP, Vista, Win7, both 32 and 64 bit but there were some issues:
    at first i could only use them on separate machine because included drivers were incompatible with other units i had. this meant constant struggle and reloading drivers depending which unit was at hand. also windows updates would bring certified drivers after which the affected (bad) units would no longer work under Win7 and Ultra has no driver updates (which did not design product itself, just trying to market some cheap crap made by others). eventually i just gave those to my buddy who put them on couple machines running XP.

    my message is, be careful with what you choose. just because you have product claiming Win7 compatibility and including CD with driver, and no other units (no driver conflicts) you can still get screwed in the long run. if you ask me get only product from known brand and make sure the have decent driver support on their website.
     
    Last edited: Sep 18, 2013
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