Ed,
what happens if you just catch the exception from your detach command?
Eg.
try:
self.handle.detachKernelDriver(0)
except usb.USBError, err:
print >> sys.stderr, err
Otherwise, if the kernel driver is already detached, you will not claim
the interface.
Regards,
-Thomas
Am Samstag, den 16.05.2009, 21:34 -0700 schrieb ed:
> When I first run my program everything is OK. That is I can detach the
> kernel interface and then claim the interface and then release
> the
> interface.
>
> TERMINAL OUTPUT
> e...@ed-desktop:~/Desktop$ sudo ./DelcomUSBDevice.py
> Found Delcom Device
> Claiming interface
> Manufacturer: Delcom Products Inc.
> Product: USB IO Controller
> Bytes written %s 8
> Sleep 2 seconds
> close done
>
> But if I run the program a 2nd time or more I get two errors.
> 1. could not detach kernel driver from interface 0: No data
> available
> 2. No interface claimed
>
> TERMINAL OUTPUT
> e...@ed-desktop:~/Desktop$ sudo ./DelcomUSBDevice.py
> Found Delcom Device
> could not detach kernel driver from interface 0: No data
> available
> Manufacturer: Delcom Products Inc.
> Product: USB IO Controller
> Bytes written %s 8
> Sleep 2 seconds
> No interface claimed
> e...@ed-desktop:~/Desktop$
>
>
> Any clues to why this is happening?
>
>
> MY PROGRAM
>
> class DelcomUSBDevice(object):
>
>
> # Device Constants
> VENDOR_ID = 0x0FC5 #: Delcom Product ID
> PRODUCT_ID = 0xB080 #: Delcom Product ID
> INTERFACE_ID = 0 #: The interface we use
>
> def __init__(self):
> '''
> Constructor
> '''
> self.deviceDescriptor = DeviceDescriptor(self.VENDOR_ID,
>
> self.PRODUCT_ID,
>
> self.INTERFACE_ID)
> self.device = self.deviceDescriptor.getDevice()
> if self.device:
> print 'Found Delcom Device'
> self.conf = self.device.configurations[0]
> self.intf = self.conf.interfaces[0][0]
> else:
> print >> sys.stderr, "Cable isn't plugged in"
> sys.exit(0)
>
>
> def open(self):
> """ Open the Delcom Interface """
> try:
> self.handle = self.device.open()
> # Detach from kernel driver on interface 0 otherwise
> # we will get device is busy
> # when we try and claim the interface because the
> kernel
> # attached to the in-kernel-HID driver.
> # Need to do only once, if you try 2nd time will get
> # message
> # "Could not detach kernel driver from interface 0:
> # no data available. Can't figure out a way to
> # only do this once.
> self.handle.detachKernelDriver(0)
> self.handle.setConfiguration(self.conf)
> print 'Claiming interface'
> self.handle.claimInterface(self.intf) # Interface 0
> except usb.USBError, err:
> print >> sys.stderr, err
>
>
> def close(self):
> """ Release Delcom interface """
> try:
> #self.handle.reset()
> self.handle.releaseInterface()
> print 'close done'
> except Exception, err:
> print >> sys.stderr, err
>
>
> def getManufactureName(self):
> """ Manufacturer of device """
> return
> self.handle.getString(self.device.iManufacturer,30)
>
>
> def getProductName(self):
> """ Product name of device """
> return self.handle.getString(self.device.iProduct,30)
>
>
> def writeData(self, data):
> self.bytesWritten = self.handle.controlMsg(0x21,
> #REQ_TYPE
> 0x09,
> #REQUEST:
> data,
> #BUFFER:
> 0x0365,
> #VALUE:
> 0x0000,
> #INDEX:
> 100)
> #TIMEOUT
>
> print 'Bytes written %s', self.bytesWritten
>
>
>
> class DeviceDescriptor(object):
> '''
> Class for defining the USB device
> '''
>
> def __init__(self, vendor_id, product_id, interface_id):
> '''
> Constructor
> '''
> self.vendor_id = vendor_id
> self.product_id = product_id
> self.interface_id = interface_id
>
> def getDevice(self):
> '''
> Return the device corresponding to the device descriptor
> if it
> is available on the USB bus. Otherwise return None.
> Note that
> the returned device has yet to be claimed or opened.
> '''
> # Find all the USB busses
> busses = usb.busses()
> for bus in busses:
> for device in bus.devices:
> if device.idVendor == self.vendor_id and
> device.idProduct == self.product_id:
> return device
> return None
>
>
>
>
>
>
>
> #main method
> def main():
> delcomUSBDevice = DelcomUSBDevice()
> delcomUSBDevice.open()
> print 'Manufacturer: ', delcomUSBDevice.getManufactureName()
> print 'Product: ', delcomUSBDevice.getProductName()
> msg = "\x65\x0C\x01\x00\x00\x00\x00\x00" # Turn on LED
> #msg = "\x65\x0C\x00\x01\x00\x00\x00\x00" # Turn Off LED
> delcomUSBDevice.writeData(msg)
> print 'Sleep 2 seconds'
> time.sleep(2)
> delcomUSBDevice.close()
>
> #allows use as a module or stand-alone script
> if __name__ == '__main__': main()
>
>
>
> Thanks
> Ed
>
>
>
>
>
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