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how to generate system clk in FRDMK64F w/o using ext osc.?

Question asked by Deepti Moodliar on Mar 7, 2016
Latest reply on May 9, 2016 by inderjitjutla

I have read many posts regarding generation of FRDMK64F system clock using IRC48M internal oscillator.

I have even tried out the suggestions given. Simplest being just changing the i/p clk of PLL to IRC48M

and modifying the PRDIV and VDIV accordingly (in file board.c of "hello_world") to generate 120MHz clock.

When this did not work, I also played around the USB related settings as mentioned in some posts.

But nothing seems to be working.  Could you Pl. guide me where I am going wrong.

 

Also, as per ref manual, using RTC osc with 32.768 KHz  crystal can also be used to generate system clock.

Could you provide me with demo code to do the same? What is the max clock freq. that can be achieved?

 

My final aim is to see whether the use of 50 MHz external oscillator can be eliminated . If yes how

and what will be the max. freq that can be achieved?

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