[pyusb-users] usb.core timeout when attempting to control OWI Edge robot arm

[Stephen R. <mor...@ho...>]

Hi list,
Hope I am doing this right...

I'm trying to use Python and pyusb1.0 running on a minimal VirtualBox installation of Debian Linux to control the OWI Edge robot arm. (I'm  trying to emulate a raspberry pi that I will use in the classroom to introduce programming and robotics, once I can actually get my hands on one)

I've been referring to this http://notbrainsurgery.livejournal.com/38622.html for technical info about the arm.

The code I am attempting to use is:

import usb.core
import usb.util

# find our device
dev = usb.core.find(idVendor=0x1267, idProduct=0x0000)

# was it found?
if dev is None:
    raise ValueError('Device not found')

# set the active configuration. With no arguments, the first
# configuration will be the active one
dev.set_configuration()

dev.write(0x81, '00,00,01', 0)

Which in theory should turn on the LED at the end of the arm. When I try to run it I get the error usb.core.USBError: Operation timed out

The code comes from the pyusb example - I also tried using the example code from pyusb with the endpoint section in with the same result.

The details about the robot arm listed from lsusb -vv are shown at the end of this email.

I'm a complete noob to USB - I assume that I've got the endpoint address and bInterfaceNumber correct in the dev.write command as it came  from the lsusb -vv details ... I assume the issue is in the formatting of the data in the write command. Writing 00 00 01 should turn on an LED at the end of the arm but I dont know how I should format this for the write command (if that is what the problem is; the timout occurs irrespectively of the string that's sent eg empty: dev.write(0x81, '', 0) still gives the error)

Any help much appreciated
Kind regards,
Steve Richards


Bus 001 Device 010: ID 1267:0000 Logic3 / SpectraVideo plc
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               1.10
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0
  bDeviceProtocol         0
  bMaxPacketSize0         8
  idVendor           0x1267 Logic3 / SpectraVideo plc
  idProduct          0x0000
  bcdDevice            0.00
  iManufacturer           0
  iProduct                0
  iSerial                 0
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           25
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              100mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass      0
      bInterfaceProtocol      0
      iInterface              0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0008  1x 8 bytes
        bInterval               8
Device Status:     0x0000
  (Bus Powered)