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rpdom
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Re: B+ and max_usb_current

Sat Aug 09, 2014 5:50 am

DRFoltz wrote:upon further inspection the wall adapter I bought was one of those dual port "1A/2.1A" wall adapters but says 3100mA in very VERY small print so I have to resolve this issue with the company I ordered from
As long as it actually provides those currents that shouldn't be a problem.

It sounds like it has one 2.1A port and one 1A port. 2.1A + 1A = 3.1A = 3100mA, which is correct.

fruit-uk
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Re: B+ and max_usb_current

Sat Aug 09, 2014 6:26 am

DRFoltz wrote:I kept having the same problem with the rainbow screen being stuck in an infinite loop.
Interesting, sounds very similar but not as extreme as my issue.

Cables may be an issue but just because it works with a B does not mean it's good enough for B+ - and only real way to tell is trial and error I think, everything is much too small to try measuring. PSUs similar, and what it says on the tin is not necessarily what's inside!

Do try any alternatives you have, they are the most likely cause IMO.
I later did the raspi-update command to try the max_usb_current=1 setting in the config.txt and after that I got a small rainbow box in the right hand side anytime I plugged in the HD.
That square is an under-voltage warning.
I was also using a wired hub for the HD and a wired xbox360 controller but those were drawing from the hub of course.
I think there is still some current draw even using a powered hub, how much may depend on its design. Others will know more and correct me if I'm wrong I'm sure.
With the HD plugged in on NOOBS Raspbian one setting (safe_mode_gpio=4) the red PWR led blinked at a constant interval. On the other (max_usb_current=1) no red led was present and the green ACT led was faint but blinking in rapid succession
The red LED should be lit and steady. The only time mine is completely unlit is when unpowered.
anytime I've come to you guys before with questions I feel like I've been misconstrued and made to feel rather stupid.
Ah yes, the internet :)
compatiblity issue with HDs as well, some might draw more power than others.
That may depend on how you intend to use them. Through a powered hub should be no big issue assuming the hub can cope.

If you want to use it for the OS I believe it will need to plugged directly in to the B+ in which case there may be power issues but I have read reports that others have done it and that is what I intend with mine. Hope to get to that later today - I don't do youtube.

gkreidl
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Re: B+ and max_usb_current

Sat Aug 09, 2014 6:45 am

fruit-uk wrote: If you want to use it for the OS I believe it will need to plugged directly in to the B+ in which case there may be power issues but I have read reports that others have done it and that is what I intend with mine. Hope to get to that later today - I don't do youtube.
No, the HD with the root files system can be connected to a hub also; in fact, that is usually the only chance you have with a B.
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rpdom
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Re: B+ and max_usb_current

Sat Aug 09, 2014 6:54 am

gkreidl wrote:
fruit-uk wrote: If you want to use it for the OS I believe it will need to plugged directly in to the B+ in which case there may be power issues but I have read reports that others have done it and that is what I intend with mine. Hope to get to that later today - I don't do youtube.
No, the HD with the root files system can be connected to a hub also; in fact, that is usually the only chance you have with a B.
Or an HD with its own PSU (not common with 2.5" drives, but fairly common with 3.5" like I use.

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Re: B+ and max_usb_current

Sat Aug 09, 2014 7:03 am

rpdom wrote:
Or an HD with its own PSU (not common with 2.5" drives, but fairly common with 3.5" like I use.
Yes, of course, but many newer USB drives take only the 12V from their own power supply and the 5V from USB. I can connect some of my older drives to the RPi directly but none of my newer ones.
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Re: B+ and max_usb_current

Sat Aug 09, 2014 7:10 am

gkreidl wrote:No, the HD with the root files system can be connected to a hub also; in fact, that is usually the only chance you have with a B.
Do you really mean B? I have two Bs here with HDs plugged directly, they do have separate power leads to a common supply however.

I'd appreciate it if you could give me some pointers as to how get things running via a hub. I've abandoned previous early attempts as it seems to fail waiting for the external hub to come up IIRC. ISTR reading of problems with linking through too many hubs too.

I was hoping later today to try with a Seagate Expansion 500Gb - I do have a Y lead for that.

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Re: B+ and max_usb_current

Sat Aug 09, 2014 7:29 am

I'm using it for about a year now. Use a 4-port-hub, not a cascaded 7-port-hub.

Follow this tutorial:
http://www.raspberrypi.org/forums/viewt ... tem+to+usb

You may have to add a delay into your cmdline.txt. I'm using:
rootwait rootdelay=5
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fruit-uk
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Re: B+ and max_usb_current

Sat Aug 09, 2014 8:02 am

gkreidl wrote:I'm using it for about a year now. Use a 4-port-hub, not a cascaded 7-port-hub.
Thanks. I've always used 7 port, could be why I've had problems running from a hub.
Follow this tutorial:
http://www.raspberrypi.org/forums/viewt ... tem+to+usb

You may have to add a delay into your cmdline.txt. I'm using:
rootwait rootdelay=5
Think that was the thread I read when I set mine up. I use the rootdelay on both HD setups too.

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Re: B+ and max_usb_current

Sat Aug 09, 2014 11:05 am

Thanks RaTTus for the CPC link, as you say returns are easy. Rather surprised to be assured of no need to include a description of the fault, I'll include something anyway.

I have just had a very quick try at installing to the Seagate on the B+. Only tried a single installer but the HD is not recognised either with plugging the HD straight into the B+ or using a Y lead for additional power. I'm not really surprised and suspect the default current limiting has a lot to do with it.

Perhaps transferring an up to date install may work but I'll leave that for someone else to try. I am expecting to be able to swap the B+ with a B currently running from HD, maybe later today - if I can face the mass of wires.

DRFoltz
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Re: B+ and max_usb_current

Fri Aug 22, 2014 4:56 pm

Just wanted to update saying I now have a better quality 2Amp power supply and all is running smoothly! :mrgreen: I can now use HD with either Raspbmc or Raspbian. The old PSU was terrible as even in the 1A usb plug it put my model B on the fritz :shock: when trying to set it up at my buddy's house. It made the Pi run so slow and then it would just freeze. Basically it was a cheapo piece of junk. I don't think it had a regulator so it was putting out 3.1A to either plug whether it was the 2.1 plug or the 1.0 plug. I don't know for sure but we trashed it and I gave my friend my old usb wall adapter and usb cable for the model B once I got my new PSU for the B+.

coralnut
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Re: B+ and max_usb_current

Thu Jan 01, 2015 7:05 am

Are the parameters "same_mode_gpio=4" and "max_usb_current=1" something that will only work in Raspbian, or can they be used in Pidora?

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Re: B+ and max_usb_current

Thu Jan 01, 2015 10:25 am

Don't post the same question in two places it's against forum netiquette.
http://www.raspberrypi.org/forums/viewt ... 51&t=95388
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Re: B+ and max_usb_current

Sat Oct 03, 2015 6:12 am

I verified that max_usb_current=1 in the /boot/config.txt file does indeed take the mosfet pin hi. But what this is really all about is the power supply you're using. Rule No. 1, never believe a current rating printed on a 5v plugpack. I hooked a 10 ohm rheostat across one of the usb outputs & put an ammeter in series with the 5v supply to the Pi. I then wound the rheostat down while watching the supply current & the red power led. There was bugger all correlation. Some 1A rated plugpacks did better than 2A.

Finally, suspecting variations in wire thickness/length in the plugpack leads, I rigged up a 5v 5A lab power supply with short thick cables & tried again. Results below.

Stndby current into a B+ Pi at idle 0.21A
Max supply current before the red led starts flickering (indicating low voltage) 0.72A (ie 0.72-0.21=0.51A out the USB). This result was INDEPENDENT of the GPIO38 pin state as controlled by the entry in the /boot/config.txt file. High or low on the mosfet pin, it made absolutely no difference.

dunk8888
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Re: B+ and max_usb_current

Sun Jan 03, 2016 1:50 am

"1A/2.1A" wall adapters but says 3100mA" It means combined lol doh

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