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USB to Parallel adapter?

Discussion in 'Electronic Design' started by Terry Pinnell, Jun 27, 2006.

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  1. As a PC 'scope in my shed/workshop I use the 'ADC-200/50' from Pico
    It's one of their older products and so has a parallel port connector,
    not USB like the new stuff.

    The ancient W98 PC in the shed is very unreliable I'm replacing it
    with a mid-range laptop. But of course that won't have a parallel

    I phoned Pico Technology today and was surprised to be quoted a VAT
    inclusive price of £59 UKP (about $110 USD) for their adapter.

    The site says it's designed for only for Pico's products. But I
    already have 'their' parallel cable, so what are my chances of getting
    a 'standard' USB to parallel adapter, hopefully much cheaper, and
    simply then plugging in the old cable?
  2. Joerg

    Joerg Guest

    Hello Terry,
    Walmart has one that is claimed to be bidirectional. No idea how
    compatible it would be in this case:

    If you don't have Walmwart stores there are some in Germany.
  3. Jim Thompson

    Jim Thompson Guest

    "Walmwart" is what I call them too ;-)

    ...Jim Thompson
  4. I had the same problem with a Velleman (PCS500) scope. I ended up
    with a PCIMIA card to give me a real LPT port. That also works for my
    Xilinx cable too. No cheaper though.

    I originally got a usb to parallel adaptor which said it was IEEE1284
    (or some number), bidirectional. Good enough I thought but it wasn't.
    No drivers except for printers and not all printers work either so I
    now read.

    Personally I'd go for the real LPT route as it works with more stuff.
  5. I do not know if you have an equivalent of "Radioshack" in the UK, but
    if so, try buying a USB to parallel adapter, and return it if it does
    not work. There is no risk for you.

    I had a similar issue with a laptop and SERIAL port, and a Radioshack
    adapter worked. (and the one I bought new from ebay for 6 times less
    did not work).

  6. Joerg

    Joerg Guest

    Hello Jim,
    I don't like much going there because of their slow lines. But when it
    comes to mundane stuff such as pool chlorine their prices are hard to
    beat. And their Kilz paint is quite good and reasonably priced.

    It's also a good place to browse the toy and computer sections for ideas
    on who to make electronics cheaper.
  7. Guest

    It's also a good place to browse the toy and computer sections for ideas
    "on who to make electronics cheaper"
    Eh..? ;)
  8. Guest

    Why is it unreliable?

    Try re-formatting and installing Windows 2000. Failing that, make sure
    the CPU has sufficient thermal paste (I learned this the hard way!),
    and make sure the RAM is seated properly.

    Try running Prime95's torture test overnight too.

  9. Joerg

    Joerg Guest

    Ahem, "how". But "who" is also an interesting topic. Sometimes it's good
    to buy something and look what brand of LCD they used, and so on.
  10. Almost zero.
    The key is that the adapters should not really be described as 'USB to
    parallel' adapters, but as _printer_ adapters. They perform the operations
    associated with operation of the parallel port as a printer control
    device, fine. However they lack the abilities present in the 'real' port,
    where bits can be set/cleared/read at relatively precise times. It is
    actually good, that Pico have an adapter. Otherwise you would need to look
    at the cost of a PCMCIA parallel printer card instead. The same problem is
    present for things like many old scanners, homebrew milling machines, and
    some cameras, using the parallel port, which the 'off the shelf' USB
    adapters, will not drive.

    Best Wishes
  11. Si Ballenger

    Si Ballenger Guest

    Business grade laptops often have parallel ports (but more $$$).
    I'd just get the old computer running again, or get a new fast
    box and put a parallel port card in it. The USB to parallel
    adapters only work with printers (no bit banging).
  12. Jim Thompson

    Jim Thompson Guest

    I would think that one of you bit-bangers could design a USB-to-LPT
    device and then write software to take parallel port commands and
    convert them to USB (and back). No?

    ...Jim Thompson
  13. Joerg

    Joerg Guest

    Hello Jim,

    I was told by a (pretty good) Windows programmer that such a task of
    near realtime control via USB can quickly turn into a major nightmare.
    Deadline is near, stuff don't work, coffee, more coffee, Prozac...

    You have to deal with numerous intricacies of Windows, a product that
    isn't exactly known for flawlessness. Plus I guess the market potential
    for a bitbang capable device would be slim.
  14. <snip>

    There would be timing issues with the USB stack, plus you couldn't work
    around the timing issues with out knowing what they would be.
    But you could create a stack that could handle the timing for you, sort of
    extended instruction set. Then Open source publish it.
    I'm sure someone will write one, as the Parallel port is next on the list
    for obsolesance.

  15. Jim Thompson

    Jim Thompson Guest

    So bit-bangers aren't up to analog-level design ?:)

    ...Jim Thompson
  16. Si Ballenger

    Si Ballenger Guest

    Even if you got a new laptop with a parallel port, the O-scpoe
    software might not work with it. Hardware timing with XP will
    probably not be as quick and acurate as with win98, and the
    software may not have proper drivers to work with XP. I've got
    aToshiba laptop with a parallel port, and I haven't been able to
    bitbang it as of yet.
  17. Actually the USB bus is time sliced at 1ms chunks, so even the best case
    would be a 2ms + pulse when bit banging. A far cry from DOS and a fast PCI
    port. Thats why most attempts fail. You need smarts in the adaptor, but that
    affects copmpatibility.

  18. mc

    mc Guest

    Even if you got a new laptop with a parallel port, the O-scpoe
    Basically, the problem is that XP is a real operating system. 98 will
    happily drop down into a mode very much like DOS. XP will not; XP never
    gets out of the picture. That is why XP is considerably less crash-prone
    than 98.
  19. Many thanks for all those helpful replies. Quite a bit to think about.

    Getting the old W98 PC working reliably (perhaps under an alternative
    OS such a W2000 as Michael suggests) certainly seems the most cost
    effective solution. But, apart from its current unreliability, and my
    unwillingness to invest much more time on it, two other factors
    favouring a laptop are

    - Space; the 17" Ilyama and the largish PC tower would release some
    handy room

    - I'd like to play with the laptop in house and garden. (Although
    this will inevitably increase hassle from my wife about spending too
    long at my computer already <g>).

    A guy sat down opposite me on the train and opened up his HP laptop -
    which had a parallel port. He reckoned it was "a year or so old." So
    I'd think seriously about an older notebook, but for the warnings that
    even that might not work.
  20. OBones

    OBones Guest

    Look closely, some brand new laptops have the parallel port, but they
    most often are in the "desktop replacement" category.
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