USB in python

[Diez B. Roggisch]

Astan Chee schrieb:
> 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.

If all you need is on-off - why can't you just use a switch?

Diez