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Free my P8x32A from USB — Parallax Forums

Free my P8x32A from USB

TheVigTheVig Posts: 41
edited 2012-10-30 21:04 in Propeller 1
Ok. So now I got my little project working and I thought I'd be able to power the thing from a 5V power supply via the USB connection, but it doesn't work.

What do I need to do to free my QuickStart from the USB?

Is it just connect a 4-9V power supply to Pin 40 and 39 on the header?

I don't want to release the smoke!

-Jim

Comments

  • TheVigTheVig Posts: 41
    edited 2012-10-30 16:08
    Took the risk. Connected up a 5V power supply to the Vin - Unregulated 4 to 9 VDC Input and YES!
  • prof_brainoprof_braino Posts: 4,313
    edited 2012-10-30 17:16
    Just DON'T plug it in to the USB when the batteries are connected. Its supposed to be bad for the PC
  • LawsonLawson Posts: 870
    edited 2012-10-30 17:25
    prof_braino wrote: »
    Just DON'T plug it in to the USB when the batteries are connected. Its supposed to be bad for the PC


    If I remember right, the quickstart has a diode to prevent Vin from feeding back to Vusb so it's safe to re-program while externally powered. The quickstart also has a transistor that only powers up the regulator and Propeller after the FTDI chip has been recognized by a computer. A pull-down resistor in the right spot can force the transistor on. (or by pass it with a PTC thermal fuse)

    Lawson
  • AribaAriba Posts: 2,690
    edited 2012-10-30 18:12
    TheVig wrote: »
    Ok. So now I got my little project working and I thought I'd be able to power the thing from a 5V power supply via the USB connection, but it doesn't work....
    -Jim

    This works if you connect the /USB_PWR_EN (pin 30) at the 40pin connector to Ground.
    As Lawson said the Power from USB is only enabled if the FTDI chip has detected a USB communication. But with connecting /USB_PWR_EN to Ground you mimic this.

    Andy
  • cavelambcavelamb Posts: 720
    edited 2012-10-30 18:42
    For portable play I usually run my QuickStarts this way...
    http://www.instructables.com/id/Battery-power-for-the-QuickStart-board/
    That sends battery power to the regulator just the way it was intended.

    But with the IR thingie installed that won't work (IR board is in the way).
    So note the wire from the IR board to pin 30 (USB PWR ENABLE) and the
    Quick gets plugged into a USB type wall wart.

    The wart doesn't talk to the Quick, so the Quick won't turn on USB power
    automatically. (Hence the jumper to pin 30)

    QS-IR.JPG


    Also, I've occasionally forgotten to remove battery power when plugging in the USB cable
    from my computer. I haven't blown up anything (yet) but the Quick is ALWAYS connected via
    a powered hub.

    Dunno if that's the saving grace, or as Lawson said, it's actually fairly protected?

    But I suspect it's a bad habit to get into. Very bad...
    QS-IR.JPG
    600 x 450 - 50K
  • phil kennyphil kenny Posts: 233
    edited 2012-10-30 20:43
    If you have a USB power adapter, it works quite well.

    Here is a link to one sold by Amazon:

    http://www.amazon.com/Coby-CA81-Power-Adapter-Charger/dp/B001PRKK6G

    Just be sure to connect pin 30 to ground, but only when using this external supply.

    phil
  • Duane DegnDuane Degn Posts: 10,588
    edited 2012-10-30 21:04
    I use four AA NiMH cells in a Radio Shack battery holder (one with a built in switch) to power my QuickStart boards.

    If you really want to free your QuickStart from USB use a pair of Wixels to program the Propeller wirelessly. Martin_H shows you how here.
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