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USB Host?

Discussion in 'Electronic Design' started by Nick, Jan 22, 2006.

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  1. Nick

    Nick Guest

    I need to write data to a USB device (a printer) from a MCU. I believe I
    need a USB host controller to do this, so USB-enabled PICs etc. won't be
    suitable.

    This is purely a one-on-one configuration, there will be no other USB
    devices or hubs connected, and the make/model of printer will be
    predetermined.

    What might be the easiest way to achieve this? It's for a commercial
    application, though production qty will be low (100s).

    Thanks,
    Nick
     
  2. larwe

    larwe Guest

    Depends on the scale of the application. If it already requires a
    32-bit MCU then you could go with a PPC or ARM part that has USB host
    on-chip.

    If you're trying to do it "writ small", look at USB and USB-On-The-Go
    controllers from Cypress, Atmel et al.
     
  3. Nick

    Nick Guest

    Thanks. This is indeed a small app from the MCU's perspective (8-bit is
    fine).
     

  4. Take a look at this product :
    http://www.ghielectronics.com/USBhost.htm

    For low volumes it's probably the only viable solution as there is a lot of software involved in
    doing USB host.

    Also look at USB On-The-Go (OTG) stuff, e.g. from Philips.
     
  5. Noone

    Noone Guest

    Nick;

    This is not so difficult as it might appear. Since you are supporting only one device, it is relatively easy. You will need to get a USB analyzer (borrow, rent, buy) and simply log the data exchange between the device an a PC. You will need to capture the enumeration sequences and the data transfer sequences.

    Attach a USB host chip (like the Cypress HS811) to your uC and then program the chip to elicit the same data exchanges as observed on the PC. The learning curve will be mostly getting familiar with the USB Host chip structure, configuration and usage.

    We have done this with a number of devices.

    Blakely
     
  6. Nick

    Nick Guest

    The USBwiz looks pretty much exactly what I'm looking for. Thanks.
     
  7. Noway2

    Noway2 Guest

    I have used the Philips isp1161A1, OTG controller. It has a few quirks
    but it does work. I would also suggest that you try to find a
    reference schematic implementation as this will show you some of the
    finer details of implementing a design that works, ie where to put the
    various filter capacitors, etc. I would also recommend that you find a
    specification on PCB layout for the USB host controller. I believe
    that Intel has published one for geared towards high speed USB, which
    is backwardly compatible with full speed devices like the 1161.
     
  8. Don't know if this is relevant to your particular printer but standard USB
    printers generally assume that their supplied PC driver software will be
    doing all the bit image graphic calculations for driving the print head and
    platten etc. The printer companies will not supply this info (I've tried).

    [Rant mode ON ... For non PC use, USB is a f****** grade #1, software
    abortion.
    And thinking about it for a mS ... even for PC use.
    There, I feel better now :)
     
  9. This would be relevant, if it weren't so blatantly wrong.

    The majority of consumer printers being too dumb to do their own
    rendering exhibits a random temporal coincidence with them having USB
    ports, at best. So-called "GDI printers", a.k.a. "Windows printers"
    have existed longer than USB has been the de-facto only printer port.

    The sanity of a printer's control protocol has next to nothing to do
    with its communication technology, with only one major exception: real
    honest-to-god network printers still tend to have usable programming
    languages, like PostScript.
     
  10. Guest

    I like the section in their docs on USB Mythology!
     
  11. Huh? Maybe I'm just tuned to the wrong frequency, but how does
    that section qualify as describing mythology?


    --
    Michael N. Moran (h) 770 516 7918
    5009 Old Field Ct. (c) 678 521 5460
    Kennesaw, GA, USA 30144 http://mnmoran.org

    "So often times it happens, that we live our lives in chains
    and we never even know we have the key."
    The Eagles, "Already Gone"

    The Beatles were wrong: 1 & 1 & 1 is 1
     
  12. Rich Grise

    Rich Grise Guest

    I was wondering the same thing. Maybe dan.ellis likes it because it
    gives a fairly comprehensible explanation of the USB Black Magick. ;-)

    Cheers!
    Rich
     
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