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2014-08-02
, 19:52
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Posts: 4,118 |
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@ Ruhrgebiet, Germany
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#33
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2014-08-03
, 04:20
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Joined on Mar 2011
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#34
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2014-08-03
, 08:36
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Posts: 252 |
Thanked: 221 times |
Joined on Jul 2010
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#35
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if you want to determine what is causing massive power drainage while using usb-rj45 adapter, ...
Well, our hostmode implementation isn't a "reference one" - damn you Nokia for carrying about some stupid certification, and pulling out official hostmode support on the last moment. As a result, the fact that we have hostmode at all - even with it's speed limited by unknown reasons to under what's our WiFi offers, constant high-speed problems, and such - it's a miracle.
/Estel
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2014-08-04
, 01:16
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Joined on Mar 2011
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#36
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The Following User Says Thank You to Estel For This Useful Post: | ||
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2014-08-04
, 21:41
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Posts: 252 |
Thanked: 221 times |
Joined on Jul 2010
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#37
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Syba will not on it own, but everything - no matter if it want it or not - will charge N900 at the time of hostmoding, if you use USB Y-cable. Thanks to it, yoiu connect +5V charging device (aka any_usb_charger) in parallel (with first USB device from N900 side, in this case, a network adapter or hub) to N900, and it is it.
This way, you can charger N900 while using any USB peripherial, even without hub, as long as N900 is able to give enough current to, at least, enumerate that device - because, you need to enumerate first and then, ONLY then, attach external power to Y-cable. Other way, enumeration will fail (no hardware risk, just no working connection).
All things that require more than 200mA current to even enumerate (some external hard drives, for example) require powered hub, as those may have power attached before enumerating client. Hub is required too - obviously - if you want to use more than one device at the same time.
I've got my small, ultra-lightweight powered hub for something like 2USD (charger not included, but hacking it to charge from any other 5V power source is a piece of cake), so it's rather feasible to just use one, and carry it alongside N900.
/Estel
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2014-08-05
, 07:16
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Joined on Mar 2011
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#38
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Ok, that's pretty useful info.
But let me get this straight. You recommend using a Y-splitter USB cable and any_charger_cable to power the peripherals and, simultaneously, the N900. However, you are not using a Y-splitter yourself - you use a powered hub to charge the peripherals, which implies that the N900 is not simultaneously charged. Correct?
Also, will the N900 be charged - no matter if it want it or not - even if the selected mode is not USB host+charging?
_________ ___| +5V |___ _______ ________<USB| USB |___ [N900 ] / |_Charger_| [_______] / Y-Cable --[qwerty_] / 3th end __________ | / |USB Client| | ___ ____|___ ___ | or | --<USB||ADAP|TOR|USB>------| USB HUB | |__________| (Female to Female)
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2014-08-06
, 00:57
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Posts: 252 |
Thanked: 221 times |
Joined on Jul 2010
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#39
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No, sorry for the confusion. Is use Y-splitter cable (to be precise, a femal-to-female USB adaptor, with additional cable soldered to +5V and ground USB pins) for every hostmode use. N900 is on the one end of such cable, as a host.
then, on the other end, I may have either device itself, or a powered or un-powered hub. In all those cases, I can charge N900 simultaneously, by plugging the "3th end" of Y-cable into power source, and selecting hostmode+charging.
Hoever, this way you can't use peripherals, that require more than 200 mA current to even enumerate - because you may connect "3th end" of Y-cable (and select hostmode_charging) only after device got successfully connected, already. No device will enumerate, if +5V from external source is present already, you may connect it only AFTER you have device connected and visible by system (as stated in hostmode "manual").
For such cases (devices that draw more than 200 mA to even enumerate properly), USB hub is a must. It doesn't have anything to do with using Y-cable, you still need one for charging devices.
BTW, powered USB hubs should *never* charge host device that they're connected to - if they do (I saw some that do), it is implementation fault. They shouldn't put current "upstream".
Now, if your passive (non-powered) hub (or active one, which doesn't have charger connected, so act as a passive at the moment) follows specification strictly, it *won't* give more than 100 mA to connected peripherals. It is because passive hub is powered by other usb host (normally, up to 500 mA), so it reserver 100 mA for itself, and gives 100 mA for every of fours possible clients. Now, most hubs are internally manufactured to allow connecting of 4 peripherals, no matter, how many ports they have in reality. 7-port hubs have seven ports not incidentally - they're two hubs connected in series, internally.
There are many passive hubs, that doesn't follow specifications strictly - and they will give every peripherals as much current as they need even in passive mode, as far as they got enough power from "upstream". Normally, they're worse choice (as they will flop if, for example, you connected them to PC, and 4x 500mA-requiring USB hard disks).
Hoever, for N900, they're better, as they allow you to have the same functionality as powered hub, just by using Y-cable, as described earlier.
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2014-08-06
, 09:51
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Joined on Mar 2011
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#40
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Good info again, thanks. I have a few small questions, if you don't mind, esp. after reading the threads about h-e-n and the likes:
Ok, I guess this is because the N900 can supply no more than 200 mA (this I got from my reading elsewhere).
Not to doubt you, but could you point to the "manual"?
I guess you mean no device will enumerate if external +5V is presented to the N900 while you're trying to enumerate.
Ok, so reading this and the below, you need a powered hub for these >200mA devices. This is because a) they cannot get >200mA from the N900, and b) the >200mA they could get from a +5V external source via the y-cable would not allow for enumeration on the N900. Correct?
Ok I guess here you mean that you connect a non-compliant passive hub to a PC, and since a PC port only gives up to 500mA (it is assumed compliant) and a USB hard disk wants >500mA, the USB hard disk doesn't work, and then the user is left wondering why.
So, bottom line, if you want to charge the N900 and be able to use >200mA peripherals, so you need a y-cable and a powered hub. Yes?
Thanks esp. for the schematic. I personally will buy a y-cable because they are $2-5 only; even videos about making them recommend not doing it on your own unless you can't wait for the order to arrive.
EDIT: To test my understanding of the matter, let me pose the following solution to the >200mA peripherals problem:
You connect a y-cable to the N900. You connect a passive non-compliant hub to one of the branches. You start hostmode and enumerate the hub. Then you connect a charger to the other branch.
Then you connect a >200mA peripheral to the hub. Logic: the charger gives >200mA to the peripheral via the y-cable and the non-compliant hub. The hub has already been enumerated so there is no more enumerating to be be done on the N900, which means there is no problem with the external +5V preventing enumerating. The hub enumerates the peripheral. The peripheral will enumerate and operate because it has sufficient current. Yes? No?
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