steave
Posts: 6
Joined: Tue Nov 24, 2015 11:03 am

usb current B+

Wed Nov 25, 2015 11:27 am

I need to connect an internet key on usb.
the currents are compatible?
by testing everything is ok.
HW is sized well. can I be sure?

thanks

drgeoff
Posts: 12575
Joined: Wed Jan 25, 2012 6:39 pm

Re: usb current B+

Wed Nov 25, 2015 2:31 pm

What is an "internet key"?

And even when we know what you mean by such a generic term it will probably be helpful if you tell us the specific make and model number.
Quis custodiet ipsos custodes?

steave
Posts: 6
Joined: Tue Nov 24, 2015 11:03 am

Re: usb current B+

Wed Nov 25, 2015 7:18 pm

example:
http://consumer.huawei.com/it/mobile-br ... /index.htm


now, i'm testing with huawei k3765, hspa usb stick


the problem is not the kind of intenet key (or whatever you want to call it) but his current consumption.
nb.
the current consumption varies according to the status of connection on the network umts

How can supply B + with security?
I can't find the scheme portion of usb.

thanks

fruitoftheloom
Posts: 27226
Joined: Tue Mar 25, 2014 12:40 pm

Re: usb current B+

Wed Nov 25, 2015 7:30 pm

If you have a 5V2A PSU you can increase the USB Current from 600ma to 1200ma

https://projects.drogon.net/testing-set ... berry-pi-b

In config.txt add:

Code: Select all

max_usb_current=1
Take what I advise as advice not the utopian holy grail, and it is gratis !!

steave
Posts: 6
Joined: Tue Nov 24, 2015 11:03 am

Re: usb current B+

Thu Nov 26, 2015 11:12 am

thank you.
if you need an external power supply,
1- can i feed B+ from + 5V connector gpio and micro usb disconnected ?
I tried.
I noticed that for a moment the red light goes off, during startup.
there are contraindications?

2- you tell me where I can find the whole scheme of B +, so i understand how it works
Thanks again

User avatar
Burngate
Posts: 6502
Joined: Thu Sep 29, 2011 4:34 pm
Location: Berkshire UK Tralfamadore
Contact: Website

Re: usb current B+

Thu Nov 26, 2015 6:18 pm

The full schematic of the B+ hasn't been published.
However, from https://www.raspberrypi.org/documentati ... /README.md
and data-sheets for the 9514 USB chip and the AP2553 power-control chip, it's possible to make an educated guess as to what's going on.
I did exactly that, almost a year ago. Since I can't find my original post, here's a copy.
USBpower-B+.png

User avatar
Burngate
Posts: 6502
Joined: Thu Sep 29, 2011 4:34 pm
Location: Berkshire UK Tralfamadore
Contact: Website

Re: usb current B+

Thu Nov 26, 2015 6:41 pm

Not sure why the picture isn't appearing; I'll try again.
USBpower-B+.png
USBpower-B+.png (5.39 KiB) Viewed 1820 times

steave
Posts: 6
Joined: Tue Nov 24, 2015 11:03 am

Re: usb current B+

Tue Dec 01, 2015 7:24 am

ok. thanks.

are there problems if the power of B + is given (+5v, 2,4 pin) in gpio and not by micro usb? There are limitations to the maximum current hw? eg. size tracks etc ..

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