RM0444 Rev 5 165/1390
RM0444 Reset and clock control (RCC)
220
• CEC, with these clock sources to select from:
– HSI16 clock divided by 488
–LSE
• RTC, with these clock sources to select from:
–LSE
–LSI
– HSE clock divided by 32
The functionality in Stop mode (including wakeup) is supported only when the clock is
LSI or LSE.
• IWDG, always clocked with LSI clock.
• USB, with these clocks to select from:
–HSE
–HSI48
– PLLQCLK
• FDCAN, with these clocks to select from:
–HSE
–PCLK
– PLLQCLK
• SysTick (Cortex
®
core system timer), with these clock sources to select from:
– HCLK (AHB clock)
– HCLK clock divided by 8
The selection is done through SysTick control and status register.
HCLK is used as Cortex
®
-M0+ free-running clock (FCLK). For more details, refer to the
programming manual PM0223.