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I have a problem where I need to read a usb-stick or a usb keyboard: When I plug in the USB stick or keyboard I can't get power to the device. dmesg says nothing

I tried:

for device in $(ls /sys/bus/usb/devices/*/product); 
  do echo $device
  cat $device;

for getting information in console and I get this output:

Freescale On-Chip EHCI Host Controller 

I can't see any kingston usb stick or keyboard.


  1. How can I power my usb device mdev or /sys/bus/usb/devices/*/power
  2. How to read data from keyboard or usb stick.
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which embeded and which unix distribution do you use? – rubo77 Oct 21 '13 at 12:02
Linux version (panu@ubuntu) (gcc version 4.4.1 (Sourcery G++ Lite 2010q1-202) ) #1 PREEMPT Linux armv5tejl Built with buildroot – user257980 Oct 21 '13 at 14:09
Some very small (thin) USB sticks can be inserted upside down; try turning the usb stick over... – ChuckCottrill Oct 21 '13 at 19:52

observe the output in syslog with:

tail -f /var/log/syslog

while plugging in and out the USB-device.

If you have no syslog, install some Logging framework for embedded linux

share|improve this answer
there is no syslog in this embbedded linux – user257980 Oct 21 '13 at 11:15
maybe you find a simple logging framework in my edit – rubo77 Oct 21 '13 at 12:04
Thanks. I will try that busybox – user257980 Oct 21 '13 at 13:46
Theres no logs for usb when connecting usb stick. – user257980 Oct 21 '13 at 14:07

Solution wasn't simple.

I need to configurate /sys/class/gpio/ for enabling internal 5V step-up regulator.

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