Re: [pyusb-users] PyUSB programming error

[Wander L. C. <wan...@gm...>]

2012/5/21 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
>

ctrl_transfer call seems wrong to me, please check the pydocs, I
believe that "hexnum" argument should be in place of the "".

-- 
Best Regards,
Wander Lairson Costa