Clock Control Unit (Ckcu); Introduction - Holtek HT32F50231 User Manual

32-Bit Arm ® Cortex ® -M0+ MCU
HT32F50231/HT32F50241
6

Clock Control Unit (CKCU)

Introduction

The Clock Control unit, CKCU, provides functions of high speed internal RC oscillator, HSI, High
speed external crystal oscillator, HSE, Low speed internal RC oscillator, LSI, Low speed external
crystal oscillator, LSE, HSE clock monitor, clock prescaler, clock multiplexer and clock gating. The
clock of AHB, APB and CPU are derived from system clock, CK_SYS, which can come from HSI,
HSE, LSI and LSE. Watchdog Timer and Real Time Clock, RTC, use either LSI or LSE as their
clock source.
A variety of internal clocks can also be wired out through CKOUT for debugging purpose. The
clock monitor can be used to get clock failure detection of HSE. Once the clock of HSE does not
function (could be broken down or removed or etc.), CKCU will force to switch the system clock
source to HSI clock to prevent system halt.
Rev. 1.00 70 of 486 July 31, 2018