Forgot to mention that data is output from uC through UART. As far as I know, for RS232 cables, length of the cable should be very short in order to operate at 1Mbps. For USB, maximum cable length is 5m. However, I have read that there are some USB active extension cables, which have built-in repeaters or something. However, I am not sure whether it will provide a reliable communication link between computer and microcontroller. Does anyone have any experience in using USB extension cables with microcontrollers?