STM8 series MCU clock setting

To reduce power consumption, the clock management module can stop the clocks to the CPU, memory, and other independent peripherals.

There are four clock sources:

External high speed crystal oscillator (HSE 1-16MHZ)

Internal high speed RC oscillator (HSI 16MHZ)

External low speed crystal oscillator (LSE 32.768)

Internal low speed RC oscillator (LSI 38KHZ)

The default startup clock is internal 2MHZ (HIS/8)

The CSS clock safety system can be enabled by software. Once enabled, the system can automatically switch to HSI when the HSE stops oscillating.

CCO clock output function

1. Select the clock source

void CLK_DeInit(void) Reset all clock registers

void CLK_HSICmd(FunctionalState NewState) Enable or disable the internal high speed oscillator

void CLK_HSEConfig(CLK_HSE_TypeDef CLK_HSE) Enable, disable or bypass the external high speed oscillator

Parameters CLK_HSE_OFF CLK_HSE_ON CLK_HSE_Bypass

void CLK_ClockSecuritySystemEnable(void) CSS clock security system enable

2. Configure CPU clock

void CLK_SYSCLKSourceConfig(CLK_SYSCLKSource_TypeDef CLK_SYSCLKSource)

Parameters: CPU clock source CLK_SYSCLKSource_HSI CLK_SYSCLKSource_HSE

                    CLK_SYSCLKSource_LSI CLK_SYSCLKSource_LSE

void CLK_SYSCLKDivConfig(CLK_SYSCLKDiv_TypeDef CLK_SYSCLKDiv)

Parameters: CPU clock division coefficient CLK_SYSCLKDiv_1 CLK_SYSCLKDiv_2 CLK_SYSCLKDiv_4

      CLK_SYSCLKDiv_8 CLK_SYSCLKDiv_16 CLK_SYSCLKDiv_64 CLK_SYSCLKDiv_128

3. Enable the peripheral clocks used

void CLK_PeripheralClockConfig(CLK_Peripheral_TypeDef CLK_Peripheral, FunctionalState NewState)

The first parameter is the peripheral name, such as CLK_Peripheral_TIM1. The second parameter is enable/disable.

4. Configure other peripherals that use non-CPU clocks (RTC/LCD, BEEP, etc.)