就这么几步，

第一步： 检查STM8s.h头文件配置

/**

* @brief In the following line adjust the value of External High Speed oscillator (HSE)

used in your application

Tip: To avoid modifying this file each time you need to use different HSE, you

can define the HSE value in your toolchain compiler preprocessor.

*/

#if !defined HSE_Value

#if defined (STM8S208) || defined (STM8S207) || defined (STM8S007) || defined (STM8AF52Ax) ||

defined (STM8AF62Ax) || defined (STM8AF622x)

#define HSE_VALUE ((uint32_t)24000000) /* Value of the External oscillator in Hz*/

#else

#define HSE_VALUE ((uint32_t)16000000) /* Value of the External oscillator in Hz*/

#endif /* STM8S208 || STM8S207 || STM8S007 || STM8AF62Ax || STM8AF52Ax || STM8AF622x */

#endif /* HSE_Value */

第二步：代码配置外部时钟

CLK_DeInit();

CLK_HSICmd(DISABLE); //禁止内部高速晶振

CLK_ClockSwitchCmd(ENABLE); //使能时钟切换

CLK_ClockSwitchConfig(CLK_SWITCHMODE_AUTO, CLK_SOURCE_HSE, DISABLE, CLK_CURRENTCLOCKSTATE_DISABLE); //时钟切换（自动切换模式，切换到外部时钟，禁止切换中断，当前钟状态为）

CLK_SYSCLKConfig(CLK_PRESCALER_CPUDIV1); //配置CPU的分频器

CLK_ClockSecuritySystemEnable();

CLK_HSECmd(ENABLE);

第三步：非常重要！！检查Options配置位打开WaitState，等待时钟启动稳定。

这一步在生产烧录时不能忘了，多少有点蛋疼。。。

最后，16M到24M超频性能并不是2->3的提升，，，

详见这位大牛的分析：

/zixunimg/eeworldimg/bbs.elecfans.com/jishu_805711_1_1.html