Why does STM32 have to configure the clock first and then the GPIO?-EEWORLD

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All registers require a clock to be configured. The registers are composed of D flip-flops. Only when the clock is sent can the flip-flops be rewritten.

Any peripheral of any MCU needs a clock, and the same is true for 8051. In order to allow users to better understand power consumption, STM32 sets a switch for the clock of each peripheral, allowing users to precisely control and shut down unnecessary devices to save power.

The 51 MCU does not need to configure the IO clock, just because the same clock is used by default, which is convenient, but the power consumption cannot be reduced.
For example, a certain function is not needed, but it is still running.
STM32 needs to configure the clock, so that the power consumption of those functions that are not needed can be removed.

When you want to turn off an IO, just turn off the corresponding clock enable. However, in 51, the IO clock is not set when using IO. In STM32, there are external and internal clocks. Study the clock carefully.

ARM chips are all like this. Peripherals usually need to be clocked before their registers can be set (i.e., the peripherals can be used). STM32, LPC1XXX, etc. are all like this.
The purpose of doing this is to save power, using the so-called clock gating technology.
This also belongs to the category of synchronous circuits in circuits: synchronous circuits always require 1 clock.

Keywords：STM32 Reference address：Why does STM32 have to configure the clock first and then the GPIO?

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