The datasheet, on page 10, shows a 5v output pin. In the headers list, page 11, this pin is #12 and labeled Vusb. There is no 5v source on the board. Pin 12/Vusb only has output when the shorting pads are closed, otherwise it's floating. If the shorting pads are closed, but there is no power to the USB socket, that pin floats ~4v. So if you're doing level translation to TTL or otherwise need 5v in your application, you need to provide a separate 5v regulator/source.
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