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Kinetis KL26xx - USB clock (48 MHz) from 32.768 KHz crystal?

Question asked by Jan Kapic on Mar 10, 2014
Latest reply on Mar 11, 2014 by Mark Butcher

Hi!

 

Is it possible to get fully working USB only with 32,768 KHz crystal?

 

I am able to use FLL to get 47.972352 MHz. USB works but only with some USB host controllers. With the others USB enumeration failed with result "Unknown device". If I use 8 MHz crystal with PLL to get exactly 48 MHz, USB works with all tested  USB host controllers.

 

Tested program is the same, it only differs in clock settings.

 

Is there anyone who was able to operate USB with 32,768 KHz crystal?

 

Thanks,

 

Jan

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