I can't get UART to work when I change the clock configuration form the default. This can be recreated by setting up a new project with KSDK 1.3, modifying the UART non blocking example to work in the new project, and the adding
#define CLOCK_SETUP 1u
to the system_MK64F12.h file. If the clocks are left to run at the default speed, UART works perfectly.
I've included my example as an attachment. I am using the FRDM K64F board.
Original Attachment has been moved to: SerialTest.zip