Lego NXT brick communication error with libusb

[Rene Ladan]

Hi,

I am writing a port [1] to control the Lego NXT brick with ROS, but when
I run a test program it fails (permissions for the USB device are 666).
This is on:

% uname -a
FreeBSD acer 9.0-CURRENT FreeBSD 9.0-CURRENT #5 r216351M: Fri Dec 10
14:13:33 CET 2010     rene at acer:/usr/obj/usr/src/sys/ACER  amd64

% rosrun nxt_python color_sensor_test.py
Traceback (most recent call last):
  File
"/usr/local/ros/stacks/nxt/nxt_python/sensor_tests/color_sensor_test.py", line
42, in <module>
    test_sensors(sock.connect())
  File "/usr/local/ros/stacks/nxt/nxt_python/src/nxt/usbsock.py", line
44, in connect
    self.handle.reset()
usb.USBError: Unknown error

Looking into usbsock.py:
  self.handle = self.device.open()
  self.handle.setConfiguration(1)
  self.handle.claimInterface(0)
  self.handle.reset()
where self.device points to the USB end point for the NXT device (vendor
0x694, product 0x2)

However, if I run the same program as root it fails a bit later:

# rosrun nxt_python color_sensor_test.py
-1
Traceback (most recent call last):
  File
"/usr/local/ros/stacks/nxt/nxt_python/sensor_tests/color_sensor_test.py", line
42, in <module>
    test_sensors(sock.connect())
  File
"/usr/local/ros/stacks/nxt/nxt_python/sensor_tests/color_sensor_test.py", line
11, in test_sensors
    cs = ColorSensor(b, PORT_1)
  File "/usr/local/ros/stacks/nxt/nxt_python/src/nxt/sensor.py", line
256, in __init__
    self.set_light_color(None)
  File "/usr/local/ros/stacks/nxt/nxt_python/src/nxt/sensor.py", line
278, in set_light_color
    self.set_input_mode()
  File "/usr/local/ros/stacks/nxt/nxt_python/src/nxt/sensor.py", line
71, in set_input_mode
    self.mode)
  File "/usr/local/ros/stacks/nxt/nxt_python/src/nxt/brick.py", line 22,
in poll
    self.sock.send(str(ogram))
  File "/usr/local/ros/stacks/nxt/nxt_python/src/nxt/usbsock.py", line
65, in send
    self.handle.bulkWrite(self.blk_out.address, data)
usb.USBError: Unknown error

where self.handle is initialized in the same way as above.

It works in Ubuntu 10.10, both native and when running from VirtualBox 4
(which has USB passthrough) under the above FreeBSD.

Does anybody have an idea what could be wrong?

Thanks,
Rene

[1] ftp://rene-ladan.nl/pub/freebsd/ros-nxt-0.1.0.tar.bz2
SIZE = 3842
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