RCC clock freq in STM32F103

Question

If I select internal clock source to run my TIM3 in TM32F103 (TIMxCLK from RCC) as shown in the attached picture:

CK_INT

Then how to find out what is the freq of this clock?

I am using External Crystal 8MHz to get 72MHz as my SYSCLK.

Answer 1

TIM3 is on APB1 (see RCC_APB1RSTR).

This means in your configuration the TIM3 clock is 72 MHz, since it's derived from PCLK1 x2.