I See Two USB Ports on the P2 Eval

What are they for?
The greatest thing about logic is that, once you have followed the thought train, it is then your own.

Comments

  • 11 Comments sorted by Date Added Votes
  • One is for a USB data connection and 500ma power to the board, the other one is for power only with a greater 2A current capacity. See https://docs.google.com/document/d/1gIKAfx5slcwjrAvHnbn5VNReY2SbQxtYkgO8cIzjyyY/edit#heading=h.6frgvwkw4djo
  • One provides power, and optionally can have it's data pins connected to the P2 for software USB.
    The other is the normal USB serial connection (via FTDI chip) to pins 62/63 for programming/etc.
  • Roy Eltham wrote: »
    One provides power, and optionally can have it's data pins connected to the P2 for software USB.
    The other is the normal USB serial connection (via FTDI chip) to pins 62/63 for programming/etc.
    Does that mean that the board can't be powered off of the USB serial connection? Does it require a separate USB power connector to the other USB port?
  • David Betz wrote: »
    Roy Eltham wrote: »
    One provides power, and optionally can have it's data pins connected to the P2 for software USB.
    The other is the normal USB serial connection (via FTDI chip) to pins 62/63 for programming/etc.

    Does that mean that the board can't be powered off of the USB serial connection? Does it require a separate USB power connector to the other USB port?

    No, both USB connectors can power the board.
    pmrobert wrote: »
    One is for a USB data connection and 500ma power to the board, the other one is for power only with a greater 2A current capacity. See https://docs.google.com/document/d/1gIKAfx5slcwjrAvHnbn5VNReY2SbQxtYkgO8cIzjyyY/edit#heading=h.6frgvwkw4djo

    In science there is no authority. There is only experiment.
    Life is unpredictable. Eat dessert first.
  • kwinn wrote: »
    David Betz wrote: »
    Roy Eltham wrote: »
    One provides power, and optionally can have it's data pins connected to the P2 for software USB.
    The other is the normal USB serial connection (via FTDI chip) to pins 62/63 for programming/etc.

    Does that mean that the board can't be powered off of the USB serial connection? Does it require a separate USB power connector to the other USB port?

    No, both USB connectors can power the board.
    That's good. Don't want a rats nest of cables on my desk!

  • II ordered this one from amazon to do the brute force power.
    https://www.amazon.com/gp/product/B074KHX8CP/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
    Infernal Machine
  • Roy ElthamRoy Eltham Posts: 2,521
    edited December 2 Vote Up0Vote Down
    The problem is that most computer USB board can't deliver very much power (unless you have those new fangled power delivery USB 3.1 ports), so you'll probably want to power the board from a good usb charger/power source if you plan to do anything more than the most basic stuff.
    Especially if you are going to hang daughter boards off of it with more chips needing power.

    Publison, it's interesting how the main title of that amazon link says 3A, but the description text below says 2.5A.
  • Roy Eltham wrote: »
    The problem is that most computer USB board can't deliver very much power (unless you have those new fangled power delivery USB 3.1 ports), so you'll probably want to power the board from a good usb charger/power source if you plan to do anything more than the most basic stuff.
    I'm sure my experiments will mostly involve blinking LEDs and printing stuff to the serial port. :smile:
  • jmgjmg Posts: 12,616
    edited December 2 Vote Up0Vote Down
    David Betz wrote: »
    Roy Eltham wrote: »
    One provides power, and optionally can have it's data pins connected to the P2 for software USB.
    The other is the normal USB serial connection (via FTDI chip) to pins 62/63 for programming/etc.
    Does that mean that the board can't be powered off of the USB serial connection? Does it require a separate USB power connector to the other USB port?

    I think that depends how ambitious you are... FWIR 100mA is default and 500mA is easily configured on most USB interfaces.
    However, P2 can draw above what those can deliver.
    Generic cables may struggle even with 500mA.
    Publison wrote: »
    II ordered this one from amazon to do the brute force power.
    https://www.amazon.com/gp/product/B074KHX8CP/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

    Good idea.
    Roy Eltham wrote: »
    Publison, it's interesting how the main title of that amazon link says 3A, but the description text below says 2.5A.

    I wonder if Parallax used highest current spec'd USB connectors ?
    When you get to 2/3.5/3A not everyone agrees on who can carry what current :)

    Digkiey specs variously 1A / 1.5A / 1.8A /
    1.8A looks like the industry default, (for cheapest/highest volume stocks) which should be OK for P2

    Wurth Electronics Inc. 629105150521 specs 1A/3A, but comes at a relatively high price. It does spec 30 mΩ max & has nice solid looking body-pins.

    A good cable, with proper copper conductors, is likely to have most influence. Fatter copper on the PCB on GND/PWR can only help too...
  • VonSzarvasVonSzarvas Posts: 1,310
    edited December 2 Vote Up0Vote Down
    Yes, they are 1.8A rated. (The USB sockets)
  • Roy Eltham wrote: »

    Publison, it's interesting how the main title of that amazon link says 3A, but the description text below says 2.5A.

    By Jove, I think you are right! I can't zoom the see the actual printing.

    Infernal Machine
Sign In or Register to comment.