From owner-freebsd-usb@FreeBSD.ORG Thu Jul 21 16:36:30 2011 Return-Path: Delivered-To: freebsd-usb@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id E2A40106568A for ; Thu, 21 Jul 2011 16:36:30 +0000 (UTC) (envelope-from m.e.sanliturk@gmail.com) Received: from mail-qy0-f175.google.com (mail-qy0-f175.google.com [209.85.216.175]) by mx1.freebsd.org (Postfix) with ESMTP id 9A7E78FC17 for ; Thu, 21 Jul 2011 16:36:30 +0000 (UTC) Received: by qyk30 with SMTP id 30so3934484qyk.13 for ; Thu, 21 Jul 2011 09:36:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=cqGMmifjcTf1vVtPTEiLoSAoFFWCrO2meNWBX1gUoM8=; b=pjr4ee6AKBbrbQ8vZvDmH6EMom9B9WvljnlI2YFki+EXY7GNCENqDBcoP9p4LQZqvG yLMGKIBme4FPbSdBom3Md8QfPxcweRofDvni6EZwAP7OLEt3a5Wa4/AOlXr63O0KpJAv Qh6Dx6qRDt4iSd13CcGxTPofMrZsmYHNT5TUM= MIME-Version: 1.0 Received: by 10.224.179.67 with SMTP id bp3mr430935qab.148.1311266189783; Thu, 21 Jul 2011 09:36:29 -0700 (PDT) Received: by 10.224.11.138 with HTTP; Thu, 21 Jul 2011 09:36:29 -0700 (PDT) In-Reply-To: <4E282DCE.2070403@uffe.org> References: <4E280986.8020701@uffe.org> <4E282DCE.2070403@uffe.org> Date: Thu, 21 Jul 2011 12:36:29 -0400 Message-ID: From: Mehmet Erol Sanliturk To: Uffe Jakobsen Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: freebsd-usb@freebsd.org Subject: Re: Off-Topic: question about usb-hub power X-BeenThere: freebsd-usb@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: FreeBSD support for USB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 21 Jul 2011 16:36:31 -0000 On Thu, Jul 21, 2011 at 9:50 AM, Uffe Jakobsen wrote: > > > On 2011-07-21 14:55, Mehmet Erol Sanliturk wrote: > >> >> >> On Thu, Jul 21, 2011 at 7:12 AM, Uffe Jakobsen > > wrote: >> >> Apologies if this is a kind of off-topic for this list - since it >> does not have anything to do with FreeBSD. >> >> The external USB-hubs (v2.0) that I've come across comes in two >> categories: >> >> Some are willing to deliver power (500mA pr. connector) even if the >> hub isn't connected to a computer - and some that doesn't do this - >> the hubs that I have purchased from Dlink falls into the last category. >> >> I looking for an USB hub that is willing to deliver power without it >> beeing connected to a computer in order to drive some external units >> - no it is not a mobile-phone ;-) >> >> Could anyone give me a hint what specs to look for ? - before I >> actually buy another hub - the Dlink ones were not a success... >> >> > >> I do not know whether the above answer is correct for you or not . >> >> > Hi Mehmet, > > Thanks for your answer - it has revealed that my initial inquiry was quite > inaccurate - my apologies for that. > > I'll try to fill out the gaps. > > The product I'm referring to is a Dlink DUB-H7 ( > http://www.dlink.com/products/?pid=149). A standard USB 2.0 hub with 7 > ports that can be powered from an external power supply. > > I do know how to determine if there is power on an usb connector (pins 1+4) > - also I know the math involved in making sure that the hub is not > overloaded - but that it not really the issue here. > > This usb-hub will (apparently like so many other usb-hubs) only apply power > to its connectors if it is connected to a computer (that is running) - and > that applies even if the external power supply is connected to the usb-hub. > > Let me give you an example: > You want to charge your mobile phone but you haven't brought the charger > itself. You've only got the micro-usb cable for the mobile phone and the > above mentioned Dlink hub - also you've got no computer at hand. > Now connecting the mobile phone to the usb-hub while the usb-hub is > connected to the external power supply will not make the mobile phone start > charging. This will only happen once you connect the "uplink" usb cable from > the usb-hub and to a computer and boot it up. > > Let me add here that this has nothing to do with the complexity and > internal logic of the mobile phone mobile phone and its software - it could > be any other device that can drain its power from an usb cable. > > I've previously owned an usb hub that would deliver power without beeing > connected to a running computer - but unfortunately that was lost during > relocation - and I do not remember the model/brand. > > Now I realize that this functionality is a part of the usb standard - and > that leads to my original question: > > It there anyway to determine this habit without unpacking and testing every > the usb-hub ? > > Kind regards Uffe > > > >From the Wikipedia page http://en.wikipedia.org/wiki/USB_hub : "However, there are many non-compliant hubs on the market which announce themselves to the host as self-powered despite really being bus-powered ." It seems that the above unit is NOT using the power supply . One way to learn a suitable model is that one of the subscribers of this list knowing that will answer over time . Personally I do not know . <-------- Forget this , please : I have a Targus 7-port Hub USB 2.0 Desktop Hub with a AC Adapter Barcode : 5 024442 863608 ( ACH82EU ) Targus Europe Ltd. http://www.targus.com/uk/ In that site , search Targus 7-Port USB Desktop Hub My unit is different than the above as model number . Therefore I can not say that they are exactly equivalent , but my expectation is that they will be similar with respect to power delivery to pins . I have measured voltage across pins 1 and 4 just only it is connected to AC power line ( without any connection to any computer , even USB connection cable is not plugged ) . It is giving 5.00 volts between these two pins . I checked by reverse measuring ( to see effect of sign ) . It is giving either 5.00 or -5.00 volts when measuring pins are reversed . It is very likely that you will be able to find that model . Unfortunately , within product definition documents , mostly there is no any clue about your question . Another very simple test may to use a USB light . In computer shops it is very likely that it is possible to find "open" units for inspection by customers . Attach a USB light such as http://www.amazon.com/Portable-Flexible-Light-Laptops-Notebooks/dp/B002WI8GG8/ref=sr_1_1?ie=UTF8&qid=1311265897&sr=8-1 If it gives light , means that pins are receiving power directly from AC power supply . My knowledge is so much . Thank you very much . Mehmet Erol Sanliturk