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.
  • 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

  • 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
  • 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.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.