[pyusb-users] PyUSB programming error

[zz <z.z...@gm...>]

Dear sir/madam

When I am transmitting data by PyUSB ctrl_transfer () to EZ-USB FX2LP
microprocessor, it shows the error "Equipment connected to the system is not
functioning". Please help me to solve the problem.

The purpose of the program is: to read data form a binary file, then
transmit the data to EZ-USB byte by byte, by ctrl_transfer () function. and
the code is as following. When running it, it can transmit several bytes of
data, but the number of times is random, and than it will shows the error
message:
usb.core.USBError: [Errno None] libusb0-dll:err [control_msg] sending
control message failed, win error: Equipment connected to the system is not
functioning

*import usb.core*
*import binascii*
*import usb.util*
*import struct*
*import os*
*from os.path import getsize*
*
*
*#file read*
*binfile=open('d:/digitalTest/display.bit', 'rb')*
*x=0*
*y=os.path.getsize('d:/digitalTest/display.bit')*
*
*
*#device find*
*dev = usb.core.find(idVendor=0x04B4, idProduct=0x1004)*
*dev.set_configuration()*
*
*
*#write*
*while x<=y:*
*#    binfile.seek(x) *
*    a=binfile.read(1)*
*    print 'a',type(a)*
*    hexstr = binascii.b2a_hex(a)*
*    print hexstr, type(hexstr),x*
*    hexnum = int(hexstr,16)*
*    print hexnum, type(hexnum),x*
*    dev.ctrl_transfer(0x40, 0xaa, hexnum, 0,"",500)*
*    x += 1*
*
*
Expecting your response
zz
*
*