(#) HSE (high-speed external), 4 to 24 MHz (STM32F100xx) or 4 to 16 MHz (STM32F101x/STM32F102x/STM32F103x) or 3 to 25 MHz (STM32F105x/STM32F107x) crystal oscillator used directly or
through the PLL as System clock source. Can be used also as RTC clock source.
(#) LSE (low-speed external), 32 KHz oscillator used as RTC clock source.
(#) LSE (low-speed external), 32 KHz oscillator used as RTC clock source.
(#) PLL (clocked by HSI or HSE), featuring different output clocks:
(++) The first output is used to generate the high speed system clock (up to 72 MHz for STM32F10xxx or up to 24 MHz for STM32F100xx)