This page is the summary of me reading the reference manual, If there are missing info or incorrect info, please contact me at [email protected]

General Information

• Enable the RTC and BACKUP SRAM power to use Vbat when Vdd is out
  • A safety design, as if we lose main Vdd due to instability, we have a fallback

Different Types of Clocks & Terminology

• HSI (High speed internal clock) - Runs at 16MHz on the STM32, up to 1% Error
• HSE (High speed external clock) - More precision, external oscillator
• LSI (Low speed internal clock) - runs at 32KHz, used mostly for watchdog
• LSE (Low speed external clock) - more precision as LSI
• PLL (Phase locked loop) - pass in an input, then scale it up

Another quick definition

• RCC (Reset & Clock Controller) - Clock controller, controls buses and system clocks