what is oscillator frequency ? and how it is different from system clock frequency? [closed]

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what is oscillator frequency ? and how it is different from system clock frequency?

Answer 1

In general oscillator frequency is your source frequency from an external or internal oscillator. The microcontroller can then multiply and divide this frequency to produce a system clock that the processor core and possibly other peripherals like PWM, UART, etc. will use. The peripherals can again divide this clock to suite their own needs.

For example an internal oscillator runs at 10MHz which is multiplied by 12 and divided by 2 to produce a 60MHz system clock.

Study your microcontrollers datasheet to find how the clocks are routed and to find the registers that control the multipliers and dividers.

Update:

Using an internal PLL to multiply the frequency rather than using a high frequency oscillator reduces EMI.

Also having the option to choose the frequency is handy as we can save power by running the processor at a lower frequency or maybe optimize some timing by running the processor at a specific frequency.