USB in python

Astan Chee astan.chee at al.com.au
Fri Jan 23 08:24:37 CET 2009


Diez B. Roggisch wrote:
> Others suggested the parallel port. It is the natural choice for such 
> things, with two caveats:
>
>   - it is legacy, and thus often not available on modern hardware, 
> especially on mobile ones. So if you want it be prepared to additionally 
> buy a usb2parallel-adapter.
>
>   - it's electrical specs aren't as robust I fear. USB allos up to 500mA 
> to be drawn, and shouldn't break if you try more & fail (albeit, that 
> might be something that isn't true all the time). So you can draw quite 
> a bit of current from it (the stupid USB-cup-warmers are an example of 
> that). I have often had broken parallel-ports, and I think the reason is 
> that they *ARE NOT* specified to drive anything - they only provide 
> low-current control-lines. So whatever you design, you need a second 
> power-source then.
>
> All in all, using a USB-controller is IMHO the best solution. The 
> AT90USBKey is a low-cost evaluation-board. ATMEL provides quite a bit of 
> example-code, and there is other FOSS available.
>
> I have to admit though that the whole USB-topic isn't the easiest thing.
>
>   
Yeah, I forgot to mention that the device is requires about 70-80mA and 
the parallel port (according to the spec) only provides 1mA. Thats why I 
was looking into the USB solution.
Thanks for the suggestion though. Also, yes, the device is rather mobile 
and that is why it is powered by the computer/laptop but legacy isn't 
really an issue for me I guess.
Cheers
Astan



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