Re: [pyusb-users] Need some advice on how to speed up the Write function

[Jonas M. <jo...@pr...>]

On Sat, Jan 2, 2021 at 5:38 PM Richard Folorunso via pyusb-users
<pyu...@li...> wrote:
>
> Good evening! I'm hoping there is a way to speed up my current code as I need it to be just a bit faster to be usable.
>
> At the start of my program is this line
>
> global_out = usb.util.find_descriptor(intf,custom_match=lambda e:usb.util.endpoint_direction(e.bEndpointAddress)==usb.util.ENDPOINT_OUT)
>
> Then this line actually sends the data
>
> def sendCommand(content):
>     global_out.write(struct.pack("<I", (len(content)+2)))
>     global_out.write(content)
>
>
> The issues is this line
>
> global_out.write(struct.pack("<I", (len(content)+2)))
>
>
> Timing it, python says it takes 0.05 seconds to complete this line. I would need to get it down to 0.016 seconds in order for my program to function as intended. Is there anything I can do to optimize it?
>
> https://gist.github.com/Bluecoreg/1db99d6afcb15aab85760faa16160d05

Richard,

The timing for the transfer to complete is outside our control, it
mostly depends on the device.

But I noticed that you're sending the length in one transfer, and the
content in another... That's unusual, and perhaps the device doesn't
handle that well/fast.  Didn't you meant to write something like

    def sendCommand(content):
        global_out.write(struct.pack('<I', len(content) + 2) + content.encode())

Jonas

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