WOW-TO switch Raspberry Pi 2 Model B to operate from external 2.5" USB.HDD

https://docs.google.com/document
collaborative document: feedback, comments, corrections, suggestions appreciated, as ever

WOW-TO install an external USB.drive in Raspberry Pi 2, without need to add an external power supply

Hi all over there

this WOW-TO article generates constantly a lot of traffic, from all over the globe.....I replaced it with a short collaborative online-documentation you should use from now. I will update this in intervalls.

You are invited to comment and/or contribute to make it even better.

Pls, just follow this link to reach the online document: Wow-to: Empowering USB.port current of a Raspb..


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People without any time may take a glance on this embedded version:

USB - Stromversorgung - Erhöhung des Stromflusses durch SoftwareEingriff

Tutorial: https://docs.google.com/document/d/1Pk-KyhFfpn0N-uRCGs-bm5hmn8Jmk1apJg558RdnZn4/pub



Raspberry Pi 2 USB.drive tauglich machen:

sudo nano /boot/config.txt 

max_usb_current=1

sudo reboot

erst dann das USB.drive einstecken
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http://www.plantoschka.com/plantoschka/2015/2/8/raspberry-pi-2-externe-25-festplatte

Notwendig dafür ist ein Eintrag in der config.txt. Diese findet ihr bei Raspbian unter /boot/config.txt und bei Openelec unter /flash/config.txt
Ganzen unten in die config.txt fügt ihr folgenden Eintrag hinzu:

max_usb_current=1

• Setting max_usb_current=1 sets the available current over USB to 1.2A (default is 600mA)
• This can help if you have a decent power supply (2A, at least) and need to power something like a small external HDD or something that needs 300+ mA.
• This feature is only available on the B+ and Pi model 2 (at the time of this writing).

All that max_usb_current=1 does is to set GPIO38 high, which in turn 
turns on a FET, which connects a second 39K resistor in parallel to an 
existing one, on pin 5 of U13, the AP2553W6 USB power manager, lifting 
the current limit from 0.6A to double that (1.2A), see no possible 
scenario there why the PI resets because of that, except in case the 
gate of the FET Q4 is somehow shorted to GND. Which could be caused by a
 production fault. Inspect Q4, as look if there is solder shorting pins 
together. Also R6 (resistor mounted between gate of Q4 and GND) should 
be 100K not 0 Ohm. U13, Q4 and R6 should be near the USB ports.

http://www.raspberrypi.org/forums/viewtopic.php?f=29&t=100244

http://raspberrypi.stackexchange.com/questions/27708/is-setting-max-usb-current-1-to-give-more-power-to-usb-devices-a-bad-idea