Mittwoch, 1. April 2015

USB - Stromversorgung - Erhöhung des Stromflusses durch SoftwareEingriff


Raspberry Pi 2 tauglich machen:

sudo nano /boot/config.txt 
sudo reboot

erst dann das einstecken

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:

  • 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. 

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