公司名称：誉诚（深圳）实业科技有限公司

Auxiliary clock source: two ultra-low-power clock sources that can be used to drivethe LCD controller and the real-time clock:–32.768 kHz low-speed external crystal (LSE)–37 kHz low-speed internal RC (LSI), also used to drive the independent watchdog.The LSI clock can be measured using the high-speed internal RC oscillator forgreater precision.●RTC and LCD clock sources: the LSI, LSE or HSE sources can be chosen to clockthe RTC and the LCD, whatever the system clock.●USB clock source: the embedded PLL has a dedicated 48 MHz clock output to supplythe USB interface.●Startup clock: after reset, the microcontroller restarts by default with an internal2.1 MHz clock (MSI). The prescaler ratio and clock source can be changed by theapplication program as soon as the code execution starts.●Clock security system (CSS): this feature can be enabled by software. If a HSE clockfailure occurs, the master clock is automatically switched to HSI and a softwareinterrupt is generated if enabled.●Clock-out capability (MCO: microcontroller clock output): it outputs one of theinternal clocks for external use by the application.Several prescalers allow the configuration of the AHB frequency, the high-speed APB(APB2) and the low-speed APB (APB1) domains. The maximum frequency of the AHB andthe APB domains is 32 MHz. See Figure 2 for details on the clock tre