STMicroelectronics STM8 - Peripheral Clock Configurations

Peripheral Clock Configurations
In most codes revealed so far, I made clock configurations every time. The reasons behind so are
• Selection of right clock source.
• Adjustment of peripheral and system clocks as per requirement. Again, it is mainly intended
to balance off both power consumption and overall performance.
• Disabling any unused hardware. This reduces power consumption and help us avoid certain
hardware conflicts.
void clock_setup(void)
{
CLK_DeInit();
CLK_HSECmd(DISABLE);
CLK_LSICmd(ENABLE);
while(CLK_GetFlagStatus(CLK_FLAG_LSIRDY) == FALSE);
CLK_HSICmd(ENABLE);
while(CLK_GetFlagStatus(CLK_FLAG_HSIRDY) == FALSE);
CLK_ClockSwitchCmd(ENABLE);
CLK_HSIPrescalerConfig(CLK_PRESCALER_HSIDIV1);
CLK_SYSCLKConfig(CLK_PRESCALER_CPUDIV1);
CLK_ClockSwitchConfig(CLK_SWITCHMODE_AUTO, CLK_SOURCE_HSI,
DISABLE, CLK_CURRENTCLOCKSTATE_ENABLE);
CLK_PeripheralClockConfig(CLK_PERIPHERAL_SPI, DISABLE);
CLK_PeripheralClockConfig(CLK_PERIPHERAL_I2C, DISABLE);
CLK_PeripheralClockConfig(CLK_PERIPHERAL_ADC, DISABLE);
CLK_PeripheralClockConfig(CLK_PERIPHERAL_AWU, ENABLE);
CLK_PeripheralClockConfig(CLK_PERIPHERAL_UART1, DISABLE);
CLK_PeripheralClockConfig(CLK_PERIPHERAL_TIMER1, DISABLE);
CLK_PeripheralClockConfig(CLK_PERIPHERAL_TIMER2, DISABLE);
CLK_PeripheralClockConfig(CLK_PERIPHERAL_TIMER4, DISABLE);
}
The following lines select clock sources:
CLK_DeInit();
CLK_HSECmd(DISABLE);
CLK_LSICmd(ENABLE);
while(CLK_GetFlagStatus(CLK_FLAG_LSIRDY) == FALSE);
CLK_HSICmd(ENABLE);
while(CLK_GetFlagStatus(CLK_FLAG_HSIRDY) == FALSE);
What these lines do are enabling/disabling clock sources and wait for the sources to stabilize.
Then the following lines select clock prescalers and switching:
CLK_ClockSwitchCmd(ENABLE);
CLK_HSIPrescalerConfig(CLK_PRESCALER_HSIDIV1);
CLK_SYSCLKConfig(CLK_PRESCALER_CPUDIV1);
CLK_ClockSwitchConfig(CLK_SWITCHMODE_AUTO, CLK_SOURCE_HSI,
DISABLE, CLK_CURRENTCLOCKSTATE_ENABLE);