Raspberry Pi B+ USB Power

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Revision as of 00:09, 2 December 2014 by David (Sọ̀rọ̀ | contribs) (Created page with "It seems that the Raspberry Pi B+ by default is not configured to power a 2.5 inch self powering USB hard disk. By default it seems that the USB ports on the B+ only allow US...")
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It seems that the Raspberry Pi B+ by default is not configured to power a 2.5 inch self powering USB hard disk. By default it seems that the USB ports on the B+ only allow USB power for about 400mA. A USB hard disks uses 600mA at a minimum.

To increase the USB power to 1.2 amps 

vi /boot/config.txt

add the line 

max_usb_current=1

I believe this changes the gpio pin 38 value from 0 to 1 which opens a second resistor in parallel allowing for higher amperage over USB.

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