Another Newbie USB Hardware Question

Discussion in 'Computer Information' started by Paul, Mar 12, 2008.

  1. Paul

    Paul Guest

    Look at page 23 here:

    http://www.toradex.com/downloads/Colibri_EvaluationBoard_Schematics_Rev2.1.pdf


    Can i replace the TPS2042 with one of these:

    http://www.analogictech.com/products/digitalfiles/AAT1275.pdf


    ???

    They look to be performing the same functions, giving
    the host controller an ENABLE line, and also giving an
    Over-current Fault or Flag condition. So it looks like
    i should be able to replace the TPS2042 with the AAT1275,
    even though the former chip is only a switch, and not
    a regulator too, right?


    Thanks in advance....
     
    Paul, Mar 12, 2008
    #1
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  2. Paul

    Paul Guest

    I'm all for helping you, but the thing is, this isn't how
    you approach engineering. You look at all the requirements,
    and then decide how the existing design meets those requirements,
    and which parts have to be changed. Or whether, in fact, the
    Colibri is so far removed from what you want to do, to be a
    poor starting point.

    Your question implies a change to the power distribution system.
    As if, certain rails are not available to the thing you are
    trying to design. You need to examine all the subsystems,
    their power requirements. Also, why the designer of the
    existing design, chose to do his power conversion and
    distribution in a particular way. You make a list of all
    the power requirements for the design, and *then* make
    the call as to where to put boost or buck converters etc.
    Maybe if other parts of the design need +5V, you need a
    bigger converter.

    You'll save yourself a lot of work, if you study the design
    first, and save schematic edits, for when all of your planning
    is finished. Making a change here, and a change there, may not
    cut it. And would be the mark of an amateur.

    The AAT1275 implies you want to run a USB port, off a battery.
    It seems a rather radical shift, and suggests you're about
    to pepper us with 20 more, context free, component change
    requests.

    Also, I expect you'll soon be asking "can anybody pick out
    a 2.2uH inductor for me?". The answer to that is "No". :)
    I hate picking inductors for stuff. Page 11 of the datasheet,
    goes through some of the technical issues. For the more
    complex boost or buck switchers, some designers prototype
    the design first, and optimize it (perhaps changing inductors,
    if they don't like how the prototype is behaving). In this
    case, since the output of the AAT1275 is not powering a part
    of the main board, you could use the design itself as your
    prototyping platform, paying for your mistakes with a PCB respin.

    Some component manufacturers, make available evaluation boards,
    and maybe you could get an eval board with the AAT1275 on it.
    The advantage there, is you'd get to see the inductor they
    chose, and also have a platform for testing the circuit before
    using it. (Loading the thing up to 500mA, and seeing whether
    it regulates properly.) Of course, an eval board costs money.

    What happens with some switching converter designs, is the
    designer poorly estimates the power requirements of the
    load, and the switching converter is optimized for one
    particular load point. Suddenly, the designer discovers
    what a poor choice the thing is, because it is so close
    to overload, or not being able to drive the load. I can't
    speak to the AAT1275, and how well it does its job, but
    adding a component like that to a design, increase the
    "risk" factor.

    Paul
     
    Paul, Mar 12, 2008
    #2
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  3. Paul

    CBFalconer Guest

    Paul wrote: ()
    One (or both) of you needs a more descriptive name.
     
    CBFalconer, Mar 12, 2008
    #3
  4. Paul

    Paul Guest


    Ok, now will someone with REAL knowledge/experience
    in USB chime in and actually answer my question?
     
    Paul, Mar 12, 2008
    #4
  5. Paul

    Paul Guest

    Yes, you can use it.

    Next question.

    Paul
     
    Paul, Mar 12, 2008
    #5
  6. Paul

    David Brown Guest

    Is it just me, or does this guy Paul Quiller represent a new low with
    his antisocial responses?

    Paul Nospam clearly spent a fair amount giving you (Paul Quiller)
    helpful advice, both in this thread and a previous thread. In both
    threads, when you couldn't understand the help you were given, you
    responded by insulting the poster. You don't just need to go back to
    college and learn how to do electronics engineering (hint - it's not
    just cutting and pasting from evaluation cards) - you need to go back to
    kindergarten and learn how to play nicely with other children.
     
    David Brown, Mar 12, 2008
    #6
  7. Paul

    Chris H Guest

    Not quite... the new low is that I am going to have to publicly agree
    with you again :)
    This is getting more common. There have been a couple of threads where
    new people have also said I don't care about the social norms and
    "rules" of this group I am going to do my own thing and if you don't
    like it you can go away.

    It is one thing old hands arguing for a change but newbies who don't
    know how and why things have developed the way they have just seem to be
    diving in with no social graces at all. You can tell the don't get out
    enough because if they behaved that way in a bar they would be in
    hospital more than the bar!

    The other thing is that many do not bother to look in the manuals much
    less the online help at the tool/chip vendors web site.

    How come they can find this group on Usenet (ITS NOT A GOOGLE GROUP
    Google is just the front end viewer) but cant search the Internet
    intelligently?

    I can recall back in the mid 1990's when AOL dumped its people onto the
    net thereby causing AOL users to be known as Arse-holes On Line. Now it
    seems that every halfwit and social miss-fit can find there way here and
    behave in a way they could not in a real social interaction.

    Incidentally David I had already drafted most of my next ESE column on
    this very subject. It seems to have got a lot worse over the last few
    months. Perhaps it is just the socially inadequate have coincided with
    a new term at collage and we seem to be having more of them.

    I recall some one else had a go about this a year back?
     
    Chris H, Mar 12, 2008
    #7
  8. Paul

    Chris H Guest

    In message
    I think that was the wrong answer to some good advice.
     
    Chris H, Mar 12, 2008
    #8
  9. On s.e.d.? I think I can safely say we've gone lower! :)

    But I agree, it's pretty bad - the worst I can recall in
    comp.arch.embedded actually.
    See "the September that never ended"

    <http://en.wikipedia.org/wiki/Eternal_September>
     
    John Devereux, Mar 12, 2008
    #9
  10. Paul

    sky465nm Guest

    Incidentally David I had already drafted most of my next ESE column on

    url?
    Well if schools allow first 16-18 year olds (college). Then add 13-15 years
    old aswell (elementary). And add millions of people without academic connection
    whatsoever from the strict commercial sphere. The end result can't be an
    suprise. Can't say 99% of the people in elementary I came as across as even
    trying to have reflection over matters or vision. And now they creeped back in.
     
    sky465nm, Mar 12, 2008
    #10
  11. Paul

    David Brown Guest

    I didn't notice that the cross-posting to s.e.d. - that group has its
    own special rules for behaviour!
     
    David Brown, Mar 12, 2008
    #11
  12. Paul

    David Brown Guest

    As that great Glaswegian philosopher Billy Connolly says, "hingen's too
    good for these people - it's a good kick up the arse they need".
     
    David Brown, Mar 12, 2008
    #12
  13. I can't even tell what he wants to do. It looks like he is reinventing the
    wheel. If I understand this right, all he needs is to go out and buy a USB
    hub.

    That, and to stop insulting people that give him far more information in a
    response then he gives in a question.
     
    Jeff Strickland, Mar 12, 2008
    #13
  14. Paul

    Paul Guest

    oh, so it's ok for the other Paul to insult me
    with a huge "this isn't how you do engineering" lecture,
    but i cannot insult him back for not answering/understanding my
    question? F-that!
     
    Paul, Mar 12, 2008
    #14
  15. Paul

    Paul Guest

    You write this as if you have NEVER copied and pasted
    parts of someone else's design: TOTAL B.S.

    I suppose you'll have me re-invent the wheel, too, eh?

    Maybe you have the time to do that one......
     
    Paul, Mar 12, 2008
    #15
  16. Paul

    CBFalconer Guest

    There are at least two Pauls in this thread. It would be helpful
    if one or more of them altered his name to include at least a last
    name initial. Ignoring the politeness issue.
     
    CBFalconer, Mar 12, 2008
    #16
  17. They just did in detail.

    Robert
     
    Robert Adsett, Mar 13, 2008
    #17
  18. Paul

    David Brown Guest

    Paul Nospam was giving helpful advice, based on what you wrote - your
    suggestions were *not* how to do engineering. He wasn't insulting you -
    he was stating the facts. The same applies to other helpful posters
    (such as Andrew Smallshaw) on previous threads. These are experienced
    engineers offering their time and knowledge to help a newcomer get
    started. Your insults were petty, unprovoked and childish. If people
    don't understand your questions, it is up to *you* to explain them more
    clearly.

    And even if Paul Nospam *had* insulted you, it's still OK for him but
    not for you. He is the teacher in this thread - you are the humble
    student. If accepting insults is the cost you have to pay to learn from
    others to help *you* with *your* problem, then you have to put up with
    that. If I post a question that makes me look like an idiot, and
    someone calls me an idiot and tells me a better way to do things, then
    I'm happy with that.
     
    David Brown, Mar 13, 2008
    #18
  19. Paul

    Paul Guest

    oh, there's only one way to engineer? Lemme guess,
    YOUR WAY.



    He wasn't insulting you -
    BULLSH**.

    Good teachers are respectful when teaching, always.

    Assholes teaches first begin by telling the student how
    dumb and foolish and stupid they are, THEN spout off....
    usually without answering the question because they aren't
    as knowledgable as they think!

    This is why most engineers are afraid to ask questions:
    THEY DON"T WANT TO LOOK BAD....THEY WANT TO APPEAR
    ALL-KNOWING. BS!
     
    Paul, Mar 14, 2008
    #19
  20. You sir, are a complete idiot. USB by definition is a certain design, any
    other design is not USB.

    If you want a USB device to do a particular thing, it must do it within the
    confines of the specification. The spec is widely available, and was given
    to you. You might not like it, but it was given.

    I don't know what you are trying to do, and don't care. But it strikes me,
    and everybody else, that you asked a question then argued the answer is
    wrong. You are the one lacking respect.

    USB is a spec. The spec defines the pinouts on the various connectors by
    signals that are carried and by physical size and shape. The spec says that
    Pin 1 is always <whatever>, Pin 2 is <whatever>, and so on.

    I don't even know what the question is, and I have arrived at the fact that
    you are an idiot by the responses you have given to people that are trying
    to help. Until you began hurling insults around, I did not think anybody was
    dissing you.

    Clearly the answer you received to your original post provided far more
    information than your question gave, and your first response was,
    <paraphrasing> "Okay, anybody that really knows want to take a stab at
    this?" When the answer was very detailed. I read the question you posted,
    and my instinct was that you need a USB hub -- all of the wheel-engineering
    has already been done yet you appear to want to reinvent the wheel.
     
    Jeff Strickland, Mar 14, 2008
    #20
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