时钟供给分类
外部时钟
外部高速时钟 // HSE
– external 4-to-26 MHz crystal oscillator // 需要外接
外部低速时钟 // LSE
LSE OSC 32.768K
内部时钟
内部高速时钟 // HSI
– Internal 16 MHz factory-trimmed RC (1% accuracy)
The wakeup times given in Table 25 is measured on a wakeup phase with a 16 MHz HSI RC oscillator.
外部高速时钟
– Internal 32 kHz RC with calibration
– 32 kHz oscillator for RTC with calibration // 供独立看门狗和自动唤醒单元使用
时钟倍频分频
PLL
启动时的时钟配置
On reset the 16 MHz internal RC oscillator is selected as the default CPU clock.
The 16 MHz internal RC oscillator is factory-trimmed to offer 1% accuracy over the full temperature range.
The application can then select as system clock either the RC oscillator or an external 4-26 MHz clock source.
This clock can be monitored for failure. If a failure is detected, the system automatically switches back to the internal RC oscillator and a software interrupt is generated (if enabled). This clock source is input to a PLL thus allowing to increase the frequency up to 168 MHz.
cpu的频率
frequency up to 168 MHz