title: STM32 internal clocks
body: <p>I am confused with the clock system on my STM32F7 device (Cortex-M7 microcontroller from STMicroelectronics). The reference manual does not clarify the differences between these clocks sufficiently:<br></p>
  
  <ul>
  <li>SYSCLK</li>
  <li>HCLK</li>
  <li>FCLK</li>
  </ul>
  
  <p>The reference manual reads in chapter &lt;&lt; 5.2 Clocks >> <em>"The RCC feeds the external clock of the Cortex System Timer (SysTick) with the AHB clock (HCLK) divided by 8."</em><br>
  This statement contradicts the figure from CubeMX. Notice that in CubeMX I can choose myself the prescaler from HCLK to 'Cortex System Timer'. It is not necessarily a division by 8.</p>
  
  <p><a href="https://i.stack.imgur.com/sFmGh.png" rel="noreferrer"><img src="https://i.stack.imgur.com/sFmGh.png" alt="enter image description here"></a></p>