stm8 clock

There are 4 types of stm8 clock sources:
1. 16MHz high-speed internal clock source HSI
2. 1 to 16MHz high-speed external clock source HSE
3. 32.768KHz low-speed external clock source LSE
4. 38KHz low-speed internal clock source LSI

These 4 clock sources can be used as system clocks. You can also use an oscilloscope to measure pin 59 to see if the output clock frequency is correct. Before measuring, you need to make the following settings:

1. void main(void)  

2. {  

3.     GPIO_Init(GPIOC, GPIO_Pin_4, GPIO_Mode_Out_PP_High_Fast);  

4.   

5.     //CLK_CCOConfig(CLK_CCOSource_HSI, CLK_CCODiv_1); /* 16MHz */  

6.     CLK_CCOConfig(CLK_CCOSource_HSI, CLK_CCODiv_16); /* 1MHz */  

7.   

8.     while (1);  

9. }  

If HSI is selected as the clock output, the measured value is 16MHz without frequency division, and 1MHz if it

is divided by 16. The system clock uses HSI by default, and is divided by 8, that is, 2MHz. You can use the function CLK_GetClockFreq() to get the system clock, for example:

1. void main(void)  

2. {  

3.     uint32_t freq = CLK_GetClockFreq();  

4.     while (1);  

5. }  

It's strange. When I check the value of the variable freq through the watch window during debugging, the above writing is correct. If I change it to the following writing:

1. void main(void)  

2. {  

3.     uint32_t freq;  

4.   

5.     freq = CLK_GetClockFreq();  

6.     while (1);  

7. }  

Then there will be a problem when checking the freq value. I don't know why yet, but it may be related to the development environment.

Of course, you can also use the CLK_SYSCLKDivConfig() function to set the frequency division of the system clock. For example, if you do not divide the frequency:
CLK_SYSCLKDivConfig(CLK_SYSCLKDiv_1);
then after setting, the system clock will be 16MHz.