USB : USB Classes USB Classes for Microcontrollers |
There is one more problem you should be aware of. All CDC devices (which include those "fake serial port chips") actually waste a huge amount of USB bandwidth.
The screen shot below shows typical data measured on a CDC "USB - Serial Bridge" chip, when the chip only idling: i.e. not transferring any data at all. The measurement clearly shows that CDC devices waste 50% of the available USB bus bandwidth, even when they are not transferring any data at all.
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