What does this expression mean: (0x03 << 8) | var ? I could not see it
in the Python code...

Wander

2010/1/17 Henning Spille <h.spi...@googlemail.com>:
> Hi there,
>
> i'm trying to use this multi-plug (http://www.nw-s.net/images/sispm.jpg) with 
> pyusb. I already used it form libusbJava which is based on the libusb from 
> linux.
> As it was no problem for me to get it working in java, i'm struggling with 
> python. Well, i'm new to python (actually these are my first few lines of 
> code) but i guessed it is more an pyusb related problem - caused by me.
>
> I hoped i could convert (manually for sure) the code from libusbJava to 
> pyusb, but it does not work - yet. I attached some lines of code, dmesg 
> output and lsusb --verbose info, but i don't know if it is necessary. Please 
> can someone have a look at the controlMsg translation:
>
> Java Code:
>
> int reqtype = 0x21;
> // USB_DIR_OUT + USB_TYPE_CLASS +
> // USB_RECIP_INTERFACE /*request type*/
> int request = 0x09; // writing
> byte var = (byte) (3 * plugNumber);
> int index = 0;
> byte _on = 0x03;
> byte _off = 0x00;
> switchTo = _on;
> byte buffer[] = { var, switchTo };
> int timeout = 250;
> int size = 2;
> if (LibusbJava.usb_control_msg(handle, reqtype, request, (0x03 << 8)
>                                | var, index, buffer, size, timeout) < 0)  
> .....
>
> My pyUsb Translation:
>
>
> on = 0x03
> off = 0x00
> timeout = 250
> try:
>   print "Trying to switch"
>   var = (3 * plugNumber)
>   reqBuffer = [0] * 2
>   reqBuffer[0] = var
>   reqBuffer[1] = off
>   print "Bytes to write: " + str(reqBuffer)
>   written = handle.controlMsg(0x21, 0x09, reqBuffer,  value=0, index=0, 
> timeout=250)
>   print "Bytes written: " + str(written)
> except Exception, err:
>   print >> sys.stderr, err
>   handle, device = None, None
>
>
>
> The code works, no error in dmesg or elsewhere, but nothing happends at the 
> device - so i guess there is something wrong somewhere. Can i somehow debug 
> the communication?
>
> Would be nice if someone has some minutes to help me,
>
> Regards,
>
> Henning
> ------------------------------------------------------------------------------
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>

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Throughout its 18-year history, RSA Conference consistently attracts the
world's best and brightest in the field, creating opportunities for Conference
attendees to learn about information security's most important issues through
interactions with peers, luminaries and emerging and established companies.
http://p.sf.net/sfu/rsaconf-dev2dev
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