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USB connection without a dock

  • @Sycol Provided you wish to use the Omega as a USB host, provide a stable 5V of sufficient current and connect the grounds together, that should work.

  • @Sycol said in USB connection without a dock:

    Ok, i'm still confused.
    Can I power a usb with external 5v and connect directly its D+ and D- to the Omega's D+, D- pins or it will fry it?

    In essence, yes. USB uses 5V on VBus, but the differential signaling on the data pins is lower voltage (probably around 3.3v actually) and would normally run right into a USB capable chip. Sometimes series resistors are used to improve line termination in a the case of particular chip or board, but knowing the ideal values would require information that is not available, and it's likely to work without at least if the wiring is geometrically clean and the cable relatively short.

  • @Sycol said in USB connection without a dock:

    Ok, i'm still confused.
    Can I power a usb with external 5v and connect directly its D+ and D- to the Omega's D+, D- pins or it will fry it?

    The Onion's solution is as easy as pie.


    PRO there is a Transient Voltage Suppressor (ESD protector / surge protector) device.
    CON there isn't any kind of fuse, ie. no current limit at all.
    (?) the metal case of USB connectors are not grounded.

    Hope this helps.

  • Definetly helpful 😉

    But this schematic suffers from the same problem as the one which I presume is for the original Omega Dock... what is that part number (or equivalent) for U1 so we can reproduce the design?

    In the case of this schematic, it's D12, D13 & D15. If it's as simple as.. "well, any TVS will do the job"... well that's just dandy... but I doubt that is the case. It is supposed to supress transient voltages... so what voltage should it kick in at? 3.3v? 5v? Somewhere inbetween? It's things like this that will make it more likely that it won't be put in at all, and hence things will go wrong(tm)!


  • @Peter-Feerick
    I have an Arduino Dock 2 only.
    Its USB protector is a 6 lead SOT-23 (like) SOT-363 (accordig to WereCatf) SMD.
    Unfortunately I can't find this marking code.
    Drawing is not to scale.
    Yes, there are lots of similar devices.
    Most of them are physically too small for me. This is also very important key point. 😉

    Sorry, I can't help to choose the right one.

  • @György-Farkas said in USB connection without a dock:

    Its USB protector is a 6 lead SOT-23 (like) SMD.

    I believe the 6-pin package is called SOT-363.

  • evettttt

  • If you want to include a TVS, simply find one that some other better documented design uses for USB protection. It's quite likely you'll see USB as an advertised usage on data sheets of some.

    While a TVS isn't a bad idea, if you don't plan to use the USB port other than rarely under controlled circumstances, you may well survive without having one. The published schematics of Mediatek's own Linkit Smart module appear to show the USB connector data lines routed directly to the SoC.

  • @György-Farkas Thank you. It helps A LOT.

    When I make it gives this error and it is not an IP conflict problem. Why do I get this error? How do we fix it? I'm waiting for your help

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    alt text0_1489356373995_photoo1.png

  • @ayhan-uçar I think you're in the wrong topic.

  • @György-Farkas Much appreciated... that does indeed start narrowing things down. Damn... why couldn't that be the real size... it would be a very easy to solder SMD part! 😄 As it is... doing a bit of digging, it seems like there are a bunch of them in different SMD form factors that suitable for USB (Torex XBP1002, Bourns CDSOT23-SRV05-4, Onsemi NUP4201MR6, Semtech RClamp0504F, etc) and would do the job... but they are either nearly $2 each, or minimum order 10, so looks like my Omega2 will just have to suck it up! 💪 😮

    @Chris-Stratton My unsuspecting Omega2+ is going to be permanently connected to a 3D printer and running OctoPrint. so I have no intention of going to the hassle of sourcing a TVS just for that, especially since I won't be plugging and unplugging it. It would have been different if it had been said "oh, it's this 50 cent part here... which doesn't need a microscope to solder" 😆

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