Hi man xu,
Please use our latest KSDK sample code for MK64: KSDK2.2-FRDM-K64F120M.
You can download the sample code from this link:
Welcome to MCUXpresso | MCUXpresso Config Tools
Click "SDK bulder", choose the board as FRDM-K64, then generate the code, and download it.
You can find the interrupt code in folder: SDK_2.2_FRDM-K64F\boards\frdmk64f\driver_examples\uart
Wish it helps you!
Have a great day,
Kerry
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------