Six years ago, we wrote a post on the influence of the electric resistance of USB cables on the proper working of peripheral devices. Today, we are going to talk about a little-known related problem, which drove us to change our USB cable provider: the shielding of USB cables.
We discovered somewhat by chance the ADH-Tech GT-521F52 fingerprint reader. As it is really affordable, less than fifty US dollars, we decided to buy one two, to see what we could do with it.
Now that we finally have our small dry ice freezer, we were able to perform systematic measures of cold endurance for our sensors and transmitters. So here are the tests that we performed and the results.
You may have noticed that until now our module specifications didn't include a working temperature range. This omission could seem strange, but we didn't want to give raw numbers without accompanying them with some explanations. Indeed, although most of the modules were designed for an extended temperature range, we hadn't had the opportunity to formally valid the theoretical temperatures. Thanks to the small system built two weeks ago, it's getting ready.
The USB specification plans for 127 device adresses on the USB bus, and it is tempting to deduce from this that you can connect up to 127 devices on a USB port. Bad luck, life is not as simple: this naive reasoning does not take into account all constraints imposed by USB controllers. To give you a better and more useful answer, we have decided to test what works in real life...
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