I am using a MK60FN1M0VLQ12 in a project and using the RMII Ethernet interface. This interface requires a RMII_REFCLK from the PHY which connects to the EXTAL0 pin of the K60. I am planning on running the K60 with this clock. I also generate a RESET signal to the PHY using a GPIO pin.
However, when the PHY is reset, the REFCLK pin of the PHY is tri-stated which will kill the clock to the K60.
The MK60FN1M0VLQ12 has a second external oscillator pin, EXTAL1 which I would like to use to run the K60 using a clock that is always present. How do I power up the K60 and configure it to use the clock on EXTAL1? I understand there are some restrictions when using EXTAL1.
You can refer TWR-K60F120M board design, which is usin external 50MHz clock connect with K60 EXTAL0 pin. The 50MHz external clock also could get from tower system(50MHz clock source from TWR-SER board). You also need to check your chip mask set, which is second line print info at the chip surface.
There exists errata info 3898 (e3898: MCG: Setting the MCG_C6[PLLS] bit will enable both OSC0 and OSC1.) for both mask set: 1N96B and 3N96B. More detailed info, please check below link:
Wish it helps.