Little knowledge of STM32 system clock
What is a clock?
The clock is the basis for the operation of the single-chip microcomputer, and the clock signal drives the various parts of the single-chip microcomputer to execute corresponding instructions. The clock system is the pulse of the CPU, which determines the cpu rate. Like the human heartbeat, only with the heartbeat can people do other things, and the single-chip microcomputer can run and execute instructions and do other processing (lighting, serial port , ADC), the importance of the clock is self-evident.
Why does STM32 have multiple clock sources?
STM32 itself is very complicated, and there are many peripherals, but when we actually use it, we will only use a limited number of peripherals. Using any peripheral requires a clock to start, but not all peripherals require the system clock to be so high Frequency, in order to be compatible with equipment of different speeds, some are high-speed and some are low-speed. If high-speed clocks are used, it will inevitably cause waste. Also, the same circuit, the faster the clock, the faster the power consumption, and the weaker the anti-electromagnetic interference ability. Complex MCUs use multiple clock sources to solve these problems. So there is the STM32 clock system and clock tree.