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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