Reset and clock control (RCC) RM0453
280/1461 RM0453 Rev 1
Most peripheral clocks are derived from their bus clock (HCLK, PCLK) except the following:
• The clock used for true RNG, is derived (selected by software) from one of the following
sources:
– PLL VCO (PLLQCLK) (only available in Run mode)
– MSI (only available in Run mode)
– LSI clock
– LSE clock
• The ADC clock is derived (selected by software) from one of the following sources:
– system clock (SYSCLK) (only available in Run mode)
– HSI16 clock (only available in Run mode)
– PLL VCO (PLLPCLK) (only available in Run mode)
• The DAC uses the LSI clock in sample and hold mode
• The (LP)U(S)ARTs clocks are derived (selected by software) from one of the following
sources:
– system clock (SYSCLK) (only available in Run mode)
– HSI16 clock (available in Run and Stop modes)
– LSE clock (available in Run and Stop modes)
– APB clock (PCLK depending on which APB the U(S)ART is mapped) (available in
CRun and CSleep when also enabled in (LP)U(S)ARTxSMEN.)
The wakeup from Stop mode is supported only when the clock is HSI16 or LSE.
• The I2Cs clocks are derived (selected by software) from one of the following sources:
– system clock (SYSCLK) (only available in Run mode)
– HSI16 clock (available in Run and Stop modes)
– APB clock (PCLK depending on which APB the I2C is mapped) (available in CRun
and CSleep when also enabled in I2CxSMEN.)
The wakeup from Stop mode is supported only when the clock is HSI16.
• The SPI2S2 I2S clock is derived (selected by software) from one of the following
sources:
– HSI16 clock (only available in Run mode)
– PLL VCO (PLLQCLK) (only available in Run mode)
– external input I2S_CK (available in Run and Stop modes)
• The low-power timers (LPTIMx) clock is derived (selected by software) from one of the
following sources:
– LSI clock (available in Run and Stop modes)
– LSE clock (available in Run and Stop modes)
– HSI16 clock (only available in Run mode)
– APB clock (PCLK depending on which APB the LPTIMx is mapped) (available in
Run and CStop when enabled in LPTIMxSMEN.)
– external clock mapped on LPTIMx_IN1 (available in Run and Stop modes)
The functionality in Stop mode (including wakeup) is supported only when the clock is
LSI or LSE, or in external clock mode.
• The RTC clock is derived (selected by software) from one of the following sources:
– LSE clock