In the K32L2A Reference Manual in the USB section, Chapter 51, 51.4.24 "USB Control Register (USBx_USBCTRL) states:
Bit 5: UART Signal Channel Select. [Tx/Rx on DP/DM or DM/DP selection.]
Bit 4: Selects USB signals to be used as UART signals. [Enables the above.]
What is this talking about? If the USB module is not used for USB its pins can be used as a fourth UART? There is no other mention of this UART anyplace else other than this section.
It is clearly NOT referring to the USB CDC Serial Class.
How is the baud set? Bit format? Where to read/write data bytes etc...
As the USB Pins frequently already come out of the device, this would be a very useful debugging feature.