USvER
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Re: Doomed to use Powered Hubs

Tue Nov 01, 2011 5:37 pm

[quote]Quote from gbl08ma on November 1, 2011, 17:10
The advantage of using a microUSB plug is that it allows the Pi to be fed by a normal phone charger. It doesn\'t mean the Pi will implement the USB protocol on that micro port, though.
[/quote]
You don\'t uderstand me... There is no point to use MicroUSB plug if you don\'t trust to the power source...
But i think RasPi devs made very clever decision to offload power concerns to the PSU wich must conform to some concrete spec...

[quote]Quote from gbl08ma on November 1, 2011, 17:10
By the way, I just noticed it\'s microUSB and not miniUSB. That\'s bad for me, since I have a lot of miniUSB chargers and USB->miniUSB cables, but none that are microUSB. This means I\'ll have to buy some adapters... :(
Or I can hack the Pi by desoldering the microUSB connector and soldering a miniUSB one :)
[/quote]
Exactly!!! I have like 10 PSU and like 2 MiniUSB cables... And nan MicroUSB... And i gues guyz in nigeria have no either... Or you think they already buy some iPhone... ?

So almost all RasPi user will buy new one! Wich will definately conform to spec! Why we nead to double-ckeck that? Why we nead to cut it out?
When i buy new PSU i want it to power all my neads... And gues what i will nead not 1 but 2... Just because of some \"protection\"...
I love all this \"smart\" algorithms that think they smarter than user...

USvER
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Re: Doomed to use Powered Hubs

Tue Nov 01, 2011 5:41 pm

[quote]Quote from Lob0426 on November 1, 2011, 17:36
The Micro USB in the case of the RasPi is just for a power plug. The mention of specs for it were as to what current is it rated to carry. This plug will carry no data at all.
[/quote]
That is obvious! When i said USB spec i mean power section! And i mean not exact numbers but the assurance that PSU shuld give us a proper power that conform to the USB spec! So we don\'t nead to double check that!...

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Burngate
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Re: Doomed to use Powered Hubs

Tue Nov 01, 2011 5:43 pm

The LAN9512 data sheet states \"Full Power Management with individual or ganged
power control of each downstream port\".

[img]https://sites.google.com/site/burngateh ... s/9512.svg[/img]
so it\'s not full control, only on/off
And there\'s been no mention of what the HDMI port can be allowed, out of the total budget.
I would expect the fuse to be rated to blow before the reverse-power & over-voltage protection thingies die, or the copper tracks sparkle.

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Re: Doomed to use Powered Hubs

Tue Nov 01, 2011 5:53 pm

[quote]Quote from abishur on November 1, 2011, 01:48
[quote]Quote from carlosfm on October 31, 2011, 23:47
Something doesn\'t add up.
So the power to the USB ports is direct from the PSU?
We need a power switch on the board, so that we can turn the Pi off, along with all the connected USB devices.
I don\'t like to be disconnecting and connecting (power USB) cables or PSUs.
I\'ll have to put a power switch and so the mini USB power plug is no longer practical. Unless the input power trace on the PCB is visible (top or bottom layer) and can be cut.[/quote]

When the r-pi has power it\'s on, there is no off switch on the r-pi. That means that the only way for your usb to be getting power is if the r-pi is getting power and therefore on.

Ignoring that tid-bit, however, what he\'s actually describing is no different from a regular computer. You have the main PSU and from that PSU voltage independently runs to the processor and the peripherals. It\'s not as if the power for your USB ports on your desktop or laptop run through your processor :P[/quote]

I don\'t understand the last part of your post, the comparison is weird.
On a normal computer, when you shutdown (in the OS or the power switch) it goes to standby and powers off the USB devices and almost everything else.
How can you do this with the Pi (power off or standby), without disconnecting the power plug?
Do you Pi?

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abishur
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Re: Doomed to use Powered Hubs

Tue Nov 01, 2011 6:15 pm

[quote]Quote from carlosfm on November 1, 2011, 17:53
[quote]Quote from abishur on November 1, 2011, 01:48
Ignoring that tid-bit, however, what he\'s actually describing is no different from a regular computer. You have the main PSU and from that PSU voltage independently runs to the processor and the peripherals. It\'s not as if the power for your USB ports on your desktop or laptop run through your processor :P[/quote]

I don\'t understand the last part of your post, the comparison is weird.
On a normal computer, when you shutdown (in the OS or the power switch) it goes to standby and powers off the USB devices and almost everything else.
How can you do this with the Pi (power off or standby), without disconnecting the power plug?[/quote]

Ah re-reading your initial post, I think I was misunderstanding your basic complaint. Your actual statement is that you want a power switch on the board rather than plugging and unplugging the PSU.

I actually have a thread about adding our own in-line power switch here. Though I think it would be pretty awesome if that took one of the GPIO pairs and turned it into a power switch option. It would come jumpered out on the board so that as long as it had power it was running. Alternatively you could use your own normally open / latch close switch or button to turn the r-pi on/off through a case.
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Re: Doomed to use Powered Hubs

Tue Nov 01, 2011 6:27 pm

@USvER on one hand the Devs were smart to \"offload\" the power concerns to the PSU. But if you do not have access to a good quality PSU, as in some of the poorer countries, it could come back to bite them. And as has been pointed out, most of the USB style chargers I have seen are mini USB not micro.

OT:
As to conforming to concrete specifications. Definitely true in countries that have department or organizations to test electronics. In countries that do not have these resources it can be a real crap shoot as to quality. Knock offs are all over the place with misleading labels and logos that make them look like good quality PSU\'s. Hell they show up here in the U.S. through EBay and other places that low repute dealers can sell with little or no regulation. CAVEAT EMPTOR (LET THE BUYER BEWARE) is still true in the United States. This goes double for a good part of the rest of the world. Even Wal-Mart has had quality trouble with its imports, and it does a decent job of testing products. Remember the ultimate idea here is to get these into the hands of children all over the world, not just in England, Europe or the U.S..

I live in a rural area of California and the only two places I found micro USB chargers was Wal-Mart and RadioShack. One at $20 and the other at $30. That does not bode well for local sources around the world. If you have Internet you can find them much cheaper. If you do not have a computer or Internet then you have to rely on local sources. Time will tell if this was a good decision or not. I will admit that I am not an optimist. I do try to be optimistically pessimistic.
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Re: Doomed to use Powered Hubs

Tue Nov 01, 2011 6:29 pm

Oh, I forgot to respond to this in my last post. @USvER I\'m not certain if I\'m following your logic (so my apologies if I\'m preaching to the choir with this post ;) )there seems to be some confusion going on about the micro-usb plug. You\'re hearing micro-usb and making the appropriate and logical conclusion that it\'s literally a micro-usb port, but it\'s not. It\'s a DC Jack, except instead of using a coax plug, it\'s using the micro-usb form factor. Now like you said in your post the reason for this is that it takes care of making sure we\'re getting the right voltage (though the r-pi team still provided over-voltage control), but the issue at hand here is the current being provided. There\'s no standard for the current provided by a micro-usb power charger. I mean, technically speaking, you could grab any PSU out there with the Amperage you wanted, then slap a micro-usb port on the end of it and be good to go. The question at hand here, however, is what is the maximum current provided by the r-pi itself?

Edit: Oh and the micro over mini is apparently because that was just accepted as the standard for cell phones, but I\'m in the same boat with all my old mini plugs :P
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Re: Doomed to use Powered Hubs

Tue Nov 01, 2011 6:34 pm

[quote]Quote from Lob0426 on November 1, 2011, 18:27
@USvER on one hand the Devs were smart to \"offload\" the power concerns to the PSU. But if you do not have access to a good quality PSU, as in some of the poorer countries, it could come back to bite them. And as has been pointed out, most of the USB style chargers I have seen are mini USB not micro.[/quote]

Yet micro USB is the standard everyone is moving to. All new mobile phones, various tablets, kindles. Yes if you go to a high street store you\'ll be sold a PSU at a rip-off price. Isn\'t this the case for essentially any electrical accessory? The Foundation have said they\'ll also be selling accessories on their website, so that\'s an option if you want something known to be of an acceptable quality.

USvER
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Re: Doomed to use Powered Hubs

Tue Nov 01, 2011 7:17 pm

To all: I think we all have the same idea and just got confused :D i want to clarify:
I want either \"simple DC jack\" wich will automaticaly adjust to Voltage and Amperage... OR MicroUSB without all that...
And it wuld be great to have RasPi USB powered directly without any of hardware limitations, becouse if you use MicroUSB why you wuld do that!

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Re: Doomed to use Powered Hubs

Tue Nov 01, 2011 7:37 pm

@asb getting ripped off on the price is not so much my worry as getting a PSU that either will not work or damages the RasPi. It also is a concern that they could afford the RasPi but not the other components to operate it successfully.

When the RasPii are available I will probably adapt one of my PSU\'s to work with it. But do you have the stuff to do that? Or are you going to pay $25 for the RasPi then $30 for a power supply? Many will buy it with a PSU from the foundation. Is the foundation going to supply a PSU with the ones they give out?

Let\'s say you want to setup a netbook comparable device. You will have to start with a B model. If you use a wired keyboard and mouse you probaly just ran out of USB ports. Maybe your keyboard has a hub in it. How much power can the RasPi supply (in the original topic of this thread). You also want a web cam. You are probably ok up to this point with either a keyboard with hub or an unpowered hub. But now you need more storage for your pictures or music. One more power drawing device in the chain. So we add a USB memory stick. Now you are out of ports again most likely. At this point you are on the verge of running out of power with a 700ma PSU. Now it is time to up the overall system price by moving to a powered hub. Or are you? We don\'t know! @Jamesh alluded to you might be able to use a 1000ma PSU. But then he stated that the RasPi using 200ma (or 1watt). But it has also been stated that that 1watt figure is out the window with the new power scheme. So if you are wondering why we are all confused, maybe we are just reading too many of the posts on this forum. I have asked the questions that would clear this all up in this thread and others. Read back and you will see the questions but no real answers as of yet.
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Re: Doomed to use Powered Hubs

Tue Nov 01, 2011 7:44 pm

To those with many miniUSB chargers and no microUSB chargers: http://www.dealextreme.com/p/mini-usb-t ... pter-41527
http://www.dealextreme.com/p/micro-usb- ... ngth-36150

Also 10V-30V input 5V 2A output microUSB car charger:
http://www.dealextreme.com/p/designer-s ... v-dc-47237

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Re: Doomed to use Powered Hubs

Tue Nov 01, 2011 7:55 pm

[quote]Quote from novelty2145 on November 1, 2011, 15:50
If a compliant USB charger should be able to source 1.8 Amps by specification, why would there be any reason to make the fuse blow at a lower current?[/quote]

That\'s a good question and would get rid of the confusion.

It will not make the USB ports 2.0 specification compliant but it would allow people to use 500mA per USB port. It would also allow unpowered hubs to be used with 4 x 100mA devices.

One could reasonably ask why the fuse is even there, what exactly ( accurately, in correct technical terms ) is it protecting, or protecting from ? If it\'s just part of the reverse power connection blow-out scheme then one could wonder why it\'s there at all as the official power input is micro-USB which has connections defined by specification, and anyone doing their own wiring-up knows they are on their own anyway and always will be. The only real justification I can see is if the board tracking won\'t handle 500mA per port.

Given this fuse seems to be presenting more obstacles and difficulties than solving anything it might be an idea simply to remove it. I suspect we\'re too far along to see that happen. I still think the best solution looks to be the blob of solder on the fuse or replace it with a 1.8A fuse. If it is a track current-carrying issue then we can\'t.

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Re: Doomed to use Powered Hubs

Tue Nov 01, 2011 9:04 pm

@hippy I believe it is there to protect the RasPi, not the PSU. There is just a lot of confusion right now. They were allowing the LAN9512 to for power management of the USB ports and I have seen nothing that states that has changed. The only real change is the voltage and protection of the input power. The 5v always went to the USB ports, through poly fuse. Did anyone hear that they have made any other changes? As far as I know the LAN9512 still handles power management to the USB ports. The question is how much power can we get at those ports.

From liz:
There is a polarity protection diode. There\'s a voltage clamp, and there\'s a self-resetting semiconductor fuse. We do think about these things!

From Gert van loo:
Using linear regulators means the device will use more then the originally promised one watt. (Sorry but the price promise is what we really had to keep). I have written a document to explain why for the non-electronic engineers subscribers.
http://www.scribd.com/doc/69700160/Rasp ... More-Power

From Gert van loo:
Yes the 5V coming in goes straight to the USB. (Apart from the fuse of course.) As things stand now that 5V net is also connected to two pins on the GPIO connector. I have had some questions about that: is it 5V in or 5V out, on which I answered that a 5V copper strip does not have \'ins\' or \'outs\'.
If you really want to you can replace the fuse with a bigger one and you can connect two 1A consuming USB devices. Just make sure you pump enough current into the board. There probably is an upper limit at which the copper tracks are not sufficient for the current but I don\'t know where that is and we are then talking silly currents....

From Jacklang:
Aarrgh!
I say again 0.7A is including power drawn from the USB ports when the board acts as a host. RPi board on its own is much less, and it.

Lobo: This was in reply to someone asking if it would draw 700ma continuos.

From Gert van loo:
0.7A should be sufficient to power the BCM2835 + LAN9512 + HDMI + two USB ports drawing about 100mA each. As with most electronic equipment: under power a bit and it will give you unreliable result . If you under power a lot it will fail spectacularly. I honestly don\'t know what happens if you under power it and write to the SD card at the same time....

From Gert van loo:
abishur: Thanks Gert, is 100 mA a max for the USB ports or can they take more if I use a higher amperage PSU?

see my post in this forum from 17:59. You have to use a bigger fuse.

radix: what will be the maximum safe current passing through raspb ??

See my last remark post in this forum 19:50. But that was not serious. You never supply big currents from a distance unless you\'re desperate. You just get noise and voltage drop. Just don\'t!
That is why big USB drives have their own power socket.

Ok so here are the posts that concern the new power scheme, all from the \"power supply news\". So now you can see where the 100ma per port came from but you can also see that it is possible to give more power to the USB ports. I do not see anything that says that there is no power management to the USB ports.

So what I see here is Gert is stating that the RasPi B model \"may\" draw as much as 500ma (2.5watts?) without the USB ports drawing. I do not think they will know for sure what the draw is going to be until they have one in their hand. So if you replace the fuse to 1amp then you could get 250ma per port. Can we go up to 1.5amps? The micro USB connector can supposedly take up to 1.8amps. This would allow the full 500ma max by USB 2.0 specifications, maybe. There is an awful lot of guesstimating all through this mess, including on my part.

EDIT: this does not mean that the RasPi will draw 500ma (2.5watts). I believe Gert van loo gave a high estimate of what the RasPi might use.

Note: DO NOT try to put 2.5 amps into the board. Gert van loo was being facetious there. The connector maxs at 1.8amps. It might take it, or it might create pretty blue smoke. I vote on the smoke if I get a vote. And yes you can get a 2.5amp 5v adapter. Not in micro USB though, I think it is mini USB for the beagle board.
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USvER
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Re: Doomed to use Powered Hubs

Wed Nov 02, 2011 12:04 am

thank you!

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Re: Doomed to use Powered Hubs

Wed Nov 02, 2011 1:06 am

[quote]Quote from Lob0426 on November 1, 2011, 21:04
There is just a lot of confusion right now.
[/quote]

So true. And so frustrating that it isn\'t being clarified.

One thing I find absolutely bizarre is that it seems the power consumption of the R-Pi is quoted as including the power consumption of what\'s plugged into it. I\'ve never seen any electrical specification doing that and it makes it completely meaningless as a figure unless you know exactly what was plugged into it. It\'s also overstating power consumption when it doesn\'t need to.

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Re: Doomed to use Powered Hubs

Wed Nov 02, 2011 1:20 am

A fuse is only practical and it\'s use logical if it is protecting one device, no more than that.
This is to say that the fuse can be there to protect the Pi but NOT the USB plugs. It makes no sense. You don\'t know what people need to connect there.
You can\'t protect a full house with ONE fuse. Many things will burn before it blows.
And if it is under-rated, it will blow every day.

I know how to cut a PCB trace, though. :D
So, it\'s a power switch that it needs (it really needs! It needs connectors for a power switch, on the PCB), and a fuse bypass for the USB ports.
Do you Pi?

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Lob0426
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Re: Doomed to use Powered Hubs

Wed Nov 02, 2011 2:01 am

@carlosfm we just do not know if that is the case, in fact I believe there\'s another fuse (poly fuse) in the power management of the USB ports. These are self resetting fuses. So even if they blow they will reset. You just have to change or remove the conditions that caused it to blow.

Besides @hippy is just going to give the primary fuse a bit of solder. It would be nice to know the actual draw with no devices attached. Again I do not think they know as of yet. I also would like to see a switch but it is not that hard to contrive one. @abishur has a good suggestion in using an inline switch on the power cord. We will see many modifications to the RasPi very shortly after it is released. I am sure these forums will be full of good (and bad) tutorials. All of us may get a hand in on our own take of the RasPi.
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