Frequently Asked Questions
http://libnjb.sourceforge.net/
------------------------------

1. Is there a mailing list for users of libnjb?

   Yes.  See:

   http://lists.sourceforge.net/lists/listinfo/libnjb-users


2. When I run the sample programs, I get "No NJB devices found", or a
   silent failure (i.e., nothing happens and you get a prompt back)

   If you are on Linux, you need to mount the usbdevfs filesystem,
   and ensure that you have read/write permission to the "files"
   there.  For more information, see
   http://www.linux-usb.org/FAQ.html#gs3

   You should also verify that you have the latest libusb sources
   from SourceForge (you may need to grab them via CVS) if you 
   have libusb v0.1.3b or earlier.

   Under BSD, make sure you have read/write access to the ugen*
   and usb* devices in /dev.  ugen support will need to be built in your
   kernel (not required for BSD 5.x and higher, which builds devices
   on the fly)

3. Every other connection attempt fails with an I/O error.

   When the NJB is "released" by the host software, there is a
   brief cycle time (a few seconds or so) during which you cannot
   reattach to the device.  If you retry the command a few 
   seconds later, it may work.

   Under Linux, there appears to be a problem with the communications
   between libnjb, libusb and the USB stack.  This causes "every other
   connection fails" problems on some systems, and has not been
   root-caused.  Unplugging/replugging the device (physically!) appears 
   to get things working again, and sometimes simply retrying the 
   command works, as well.


4. I am getting bulk data transfer failures under Linux.

   This is also a known issue that appears to be an interaction between
   libnjb and libusb.  Although it has not been root-caused, the current
   suspicion is that libnjb is writing too aggressively to the USB
   stack, and usb_bulk_write may be failing on EINPROGESS.  Again, this
   is just a guess based on some scattered evidence.  There is no solution
   other than to retry. Using more recent kernels and libusb 
   implementations may solve the problem.


5. I am getting shared object/shared library errors (something like 
   "libnjb.so.0: cannot open shared object file").

   See the README file under the "Shared Library Support" section.


6. How do I get USB 2.0 working?

   First assure yourself that your hardware is really USB 2.0
   compatible. This goes for both the motherboard, hub, and the
   device you want to connect.

   Kernel 2.6.x (and newer versions of 2.4.x) have three USB driver
   modules: UHCI, OHCI and EHCI. USB 2.0 use the EHCI driver, leave
   out the others and recompile your kernel. Typical config status:

   # USB support
   CONFIG_USB=y
   # CONFIG_USB_DEBUG is not set
   # Miscellaneous USB options
   CONFIG_USB_DEVICEFS=y
   # USB Host Controller Drivers
   CONFIG_USB_EHCI_HCD=y
   CONFIG_USB_OHCI_HCD=y
   # CONFIG_USB_UHCI_HCD is not set

   See also: http://www.linux-usb.org/usb2.html