USB Interface

Discussion in 'General Electronics Chat' started by shearder, Apr 20, 2009.

  1. shearder

    Thread Starter New Member

    Apr 20, 2009
    3
    0
    Hi All

    I am new to this site and searches i have tried haven't given me what i want IF it is here already - is so, my apologies.

    Well, I am new to Programming and PIC controllers but i am really wanting to get into this so i can start making my own equipment.

    Let me give you a short description of what i want to do:

    I want to make a USB interface that I can program to act as an input device to the PC and output to 7seg LED or LCD. It can be 2 separate interfaces.

    So I hope someone can point me in the right direction in terms of CHEAPEST but good route - what IC to use etc.

    Many thanks in advance.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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  3. Papabravo

    Expert

    Feb 24, 2006
    10,166
    1,797
    You could use a PIC with specific USB hardware 18F4550(??), not sure about the part number or you could take a look at the MAX3420E and adapt that peripheral chip to any processor with an SPI port which gives you a wider choice of parts. Download the documents from www.usb.org for the protocol description. I'm guessing you want to enumerate as an HID (Human Interface Device) It will cost some bucks to get a vendor ID so a PC will recognize the device. I strongly recommend that you get a Beagle USB analyzer from Totalphase for $400.00 if you plan on doing any USB development in conjunction with a PC
     
  4. nucleargungus

    Member

    Apr 6, 2009
    23
    1
    Google "twittering toaster" and check out the iobridge.

    Robert
     
  5. shearder

    Thread Starter New Member

    Apr 20, 2009
    3
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    Do i need a vendor ID even if it is for my own personal use? i don't want to sell this stuff...
     
  6. Papabravo

    Expert

    Feb 24, 2006
    10,166
    1,797
    A PC is going to enumerate the device and it may refuse to talk to the device if it does not give an intelligent response to the vendor number question. Of course you could always pick somebody elses vendor Id but you run the risk of having the PC make invalid inferences. It is a true minefield -- I don't envy you at all. AFAIK there is no USB experimenters for my own use only category. Sorry
     
  7. shearder

    Thread Starter New Member

    Apr 20, 2009
    3
    0
    Thanks a stack for all the assistance and answers to my questions.
     
  8. n9352527

    AAC Fanatic!

    Oct 14, 2005
    1,198
    4
    The easiest route is to use USB UART chip, like FTDI245. You don't need to develop your own firmware or PC drivers. If you want to use PIC USB, this page http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2654 lists all available devices. Remember that you need to develop the USB firmware, the kernel driver and the user driver on the PC side. Microchip has examples of all these, check out the framework on the above link.

    You can get a VID:pID pair by sublicensing from Microchip, only if you use their chip. It is free, but there is no guarantee you are eligible to get one. Check this document http://ww1.microchip.com/downloads/en/AppNotes/Application%20for%20USB%20Vendor%20ID%20Sublicense.pdf

    Another, although questionable, route is to find someone that is willing to sell you a VID:pID pair, it cost a few thousand dollars to get a bulk of 64k pairs from usb.org, and they will never use all those pairs. There were a few of them a year back, but since according to usb.org it is illegal, most of them had stopped selling those pairs.
     
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