Yoctopuce Yocto-Display, Руководство пользователя, Страница: 419 / 424

23. Troubleshooting
23.1. Where to start?
If it is the first time that you use a Yoctopuce module and you do not really know where to start, have
a look at the Yoctopuce blog. There is a section dedicated to beginners
1
.
23.2. Programming examples don't seem to work
Most of Yoctopuce API programming examples are command line programs and require some
parameters to work properly. You have to start them from your operationg system command prompt,
or configure your IDE to run them with the proper parameters.
2
.
23.3. Linux and USB
To work correctly under Linux, the the library needs to have write access to all the Yoctopuce USB
peripherals. However, by default under Linux, USB privileges of the non-root users are limited to read
access. To avoid having to run the
VirtualHub as root, you need to create a new udev rule to
authorize one or several users to have write access to the Yoctopuce peripherals.
To add a new udev rule to your installation, you must add a file with a name following the "
##-
arbitraryName.rules
" format, in the "
/etc/udev/rules.d
" directory. When the system is
starting, udev reads all the files with a "
.rules
" extension in this directory, respecting the
alphabetical order (for example, the "
51-custom.rules
" file is interpreted AFTER the "
50-
udev-default.rules
" file).
The "
50-udev-default
" file contains the system default udev rules. To modify the default
behavior, you therefore need to create a file with a name that starts with a number larger than 50,
that will override the system default rules. Note that to add a rule, you need a root access on the
system.
In the
udev_conf
directory of the VirtualHub for Linux
3
archive, there are two rule examples which
you can use as a basis.
1
see: http://www.yoctopuce.com/EN/blog_by_categories/for-the-beginners
2
see: http://www.yoctopuce.com/EN/article/about-programming-examples
3
http://www.yoctopuce.com/FR/virtualhub.php
www.yoctopuce.com 413