STM32内部时钟

问题描述

我对STM32F7器件(意法半导体公司的Cortex-M7微控制器)上的时钟系统感到困惑.参考手册没有充分阐明这些时钟之间的差异:

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:

• SYSCLK
• HCLK
• FCLK

参考手册在<< 5.2时钟>> "RCC用AHB时钟(HCLK)除以8来馈送Cortex系统计时器(SysTick)的外部时钟."
这一说法与CubeMX的说法相矛盾.注意，在CubeMX中，我可以选择从HCLK到"Cortex System Timer"的预分频器.不一定是除以8.

The reference manual reads in chapter << 5.2 Clocks >> "The RCC feeds the external clock of the Cortex System Timer (SysTick) with the AHB clock (HCLK) divided by 8."
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.

推荐答案

通常HCLK和FCLK之间的唯一区别是:

Normally the only difference between HCLK and FCLK is that :

• HCLK是主CPU时钟，也用于AHB接口.可以在CPU休眠时进行门控(例如WFI)
• FCLK与HCLK同步，但是在CPU进入睡眠状态时不会被门控，因此在中断的情况下可以唤醒.

• HCLK is the main CPU clock, also used for AHB interface. It can be gated when the CPU is sleeping (WFI for example)
• FCLK is synchronous to HCLK but is not gated when the CPU goes to sleep, so that it can awake in case of interrupt.

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