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Question asked by Tom Saluzzo on Sep 17, 2015
Latest reply on Sep 20, 2015 by igorpadykov

I am confused by the relationship of the ARM Core Clock and PLL1.


Referring to the IMX6DQRM Rev 3

The diagrams in Figure 18-2 (page 796) and Figure 18-6 (page 818) shows a fixed divide by 2 block from PLL1 for the ARM_CLK_ROOT.

The equation from page 901 is: PLL Output Frequency = Fref * DIV_SEL / 2.

Is the divide by 2 in the equation from page 901 CCM_ANALOG_PLL_ARMn:DIV_SELECT the divide by 2 block in Figure 18-6?

(i.e. the equation on page 901 should be: ARM_CLK_ROOT = Fref * DIV_SEL / 2).

Otherwise, you couldn’t have an ARM_CLK_ROOT frequency of 996MHz because the DIV_SEL value would have to be 166 decimal, which is above the valid range of values (54-108).