STM32 内部时钟 [英] STM32 internal clocks

问题描述

我对 STM32F7 设备(来自 STMicroelectronics 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:

• 系统时钟
• HCLK
• FCLK

参考手册在章节<<5.2 时钟 >> RCC 将 AHB 时钟(HCLK)的 8 分频提供给 Cortex 系统定时器(SysTick)的外部时钟."
该声明与 CubeMX 的数字相矛盾.请注意，在 CubeMX 中，我可以自己选择从 HCLK 到Cortex System Timer"的预分频器.不一定要除以 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的唯一区别在于:

Normally the only difference between HCLK and FCLK is that :

• HCLK 是主 CPU 时钟，也用于 AHB 接口.它可以在 CPU 休眠时被门控(例如 WFI)
• FCLK 与 HCLK 同步，但在 CPU 进入睡眠状态时不进行门控，因此它可以在发生中断时唤醒.

• 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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