This depend of the specific part number from the K60 family you are using, for example if you are using MK60DN256VLQ10 you will see on the pin out of this device that pins 23 to 35 (and others) does not have a GPIO function assigned to them (something like PTxn, where x is a letter and n a is a number).
When you want to use a GPIO you have to make sure in which pin is assigned, normally when a pin has an GPIO associated function this will be the default option, otherwise you need to select on the PORTx_PCRn register for the pin the ALT option you want to use.
Have a nice day,
Perla Moncada
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------
