For S9KEAZ128BVLHR, what is the default BUSCLK frequency directly out of reset, assuming everything in the clock distribution module is still at default, an I am running from the internal FLL. The datasheets and the manual don't have the answer to this si

[dudley]

I have device S9KEAZ128BVLHR. I want to know default frequency of the BUSCLK directly out of reset, assuming everything is still default, I am still running from the Internal FLL, and I have not modified any registers.

The datasheets and manual don't give an answer to this very basic question.

[Robin_Shen]

Hi Dudley,

The default frequency of the BUSCLK is 24MHz, it need to be calculated by using the default values of below registers.

See the "Figure 5-1. Clocking diagram" in KEA128RM.pdf, and the default values.

The default value of IREFS bit in ICS_C1 is 1, this means Internal reference clock(37.5kHz) is selected for the FLL.

Then the FLL loop locks the frequency to 1280 times the internal reference frequency.(ICSFLLCLK=37.5kHz*1280=40MHz)

The default value of CLKS bit in ICS_C1 is 00, selects the clock source (output of FLL) that controls the bus frequency.

Best Regards,

Robin

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