STM32L151中RTC_WakeUpCmd（）函数带来了系统延时 -
[导读]ErrorStatus RTC_WakeUpCmd(FunctionalState NewState){__IO uint32_t wutcounter = 0x00;uint32_t wutwfstatus = 0x00;ErrorStatus status = ERROR;assert_param(IS_FUNCTIONAL_STATE(NewState));RTC->WPR = 0xCA;R
ErrorStatus RTC_WakeUpCmd(FunctionalState NewState)
本文引用地址: http://www.21ic.com/app/mcu/201807/779197.htm
{
__IO uint32_t wutcounter = 0x00;
uint32_t wutwfstatus = 0x00;
ErrorStatus status = ERROR;
assert_param(IS_FUNCTIONAL_STATE(NewState));
RTC->WPR = 0xCA;
RTC->WPR = 0x53;
if (NewState != DISABLE)
{
RTC->CR |= (uint32_t)RTC_CR_WUTE;
status = SUCCESS;
}
else
{
RTC->CR &= (uint32_t)~RTC_CR_WUTE;
do
{
wutwfstatus = RTC->ISR & RTC_ISR_WUTWF;
wutcounter++;
} while((wutcounter != INITMODE_TIMEOUT) && (wutwfstatus == 0x00));
if ((RTC->ISR & RTC_ISR_WUTWF) == RESET)
{
status = ERROR;
}
else
{
status = SUCCESS;
}
}
RTC->WPR = 0xFF;
return status;
}
上边时RTC唤醒的打开和关闭，在使用时，发现就RTC_WakeUpCmd（DISABLE）这个函数就要占据8ms（可怕）系统延时，这对于低功耗产品来说，不能频繁地使用此函数，否则带来不必要的浪费。
原因：在关闭时函数内部下面几句话
do
{
wutwfstatus = RTC->ISR & RTC_ISR_WUTWF;
wutcounter++;
} while((wutcounter != INITMODE_TIMEOUT) && (wutwfstatus == 0x00));
在这里要等待，可能等待时间与RTC唤醒设定的值有关系。就没有再详细的跟踪测试。
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