非常感谢香版主和ijk的及时回复!
系统时钟是用外部8MHz晶振通过PLL倍频到16MHz,我提到的系统稳定是指系统从停止模式唤醒后到恢复系统时钟为16HMz,系统正常运行.
因为之前从停止模式唤醒后发现系统时钟一直都是8MHz左右(MCO管脚输出时钟),并不是自己想得到的16MHz.参考了例程,发现STOP例程主函数的while(1)循环程序中加有一个1.5s的延时,然后在自己的程序中也加一个十几个ms(香版提到的十几个ms就是在这里,以SysTick 1ms为时基)的延时后发现系统时钟的输出就为16MHz了.怀疑唤醒后到系统稳定不应该要这么久,所以才上来找大家帮忙.
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//系统从停止模式唤醒后RCC的配置程序
void SYSCLKConfig_STOP(void)
{
/* Enable HSE */
RCC_HSEConfig(RCC_HSE_ON);
/* Wait till HSE is ready */
HSEStartUpStatus = RCC_WaitForHSEStartUp();
if(HSEStartUpStatus == SUCCESS)
{
/* Enable PLL */
RCC_PLLCmd(ENABLE);
/* Wait till PLL is ready */
while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET)
{
}
/* Select PLL as system clock source */
RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
/* Wait till PLL is used as system clock source */
while(RCC_GetSYSCLKSource() != 0x08)
{
}
}
}
-----------------------------------------------------------------
-----------------------------------------------------------------
//例程中的while(1)程序
while (1)
{
/* Insert 1.5 second delay */
Delay(1500);//唤醒之后的延时!!
/* Wait till RTC Second event occurs */
RTC_ClearFlag(RTC_FLAG_SEC);
while(RTC_GetFlagStatus(RTC_FLAG_SEC) == RESET);
/* Alarm in 3 second */
RTC_SetAlarm(RTC_GetCounter()+ 3);
/* Wait until last write operation on RTC registers has finished */
RTC_WaitForLastTask();
/* Turn off led connected to GPIO_LED Pin6 */
GPIO_ResetBits(GPIO_LED, GPIO_Pin_6);
/* Request to enter STOP mode with regulator in low power mode*/
PWR_EnterSTOPMode(PWR_Regulator_LowPower, PWR_STOPEntry_WFI);
/* At this stage the system has resumed from STOP mode
/* Turn on led connected to GPIO_LED Pin6 */
GPIO_SetBits(GPIO_LED, GPIO_Pin_6);
/* Configures system clock after wake-up from STOP: enable HSE, PLL and select
PLL as system clock source (HSE and PLL are disabled in STOP mode) */
SYSCLKConfig_STOP();
}
}
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楼主
