/* SystemFrequency / 1000 1ms中断一次
* SystemFrequency / 100000 10us中断一次
* SystemFrequency / 1000000 1us中断一次
*/
#define SYSTICKPERIOD 0.000001
#define SYSTICKFREQUENCY (1/SYSTICKPERIOD)
/**
* [url=home.php?mod=space&uid=247401]@brief[/url] 定时器2的初始化,，定时周期1ms
* @param 无
* @retval 无
*/
void TIM2_Init(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
/*AHB = 72MHz,RCC_CFGR的PPRE1 = 2，所以APB1 = 36MHz,TIM2CLK = APB1*2 = 72MHz */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
/* Time base configuration */
TIM_TimeBaseStructure.TIM_Period = 999;
TIM_TimeBaseStructure.TIM_Prescaler = SystemCoreClock/SYSTICKFREQUENCY -1;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
TIM_ARRPreloadConfig(TIM2, ENABLE);
/* 设置更新请求源只在计数器上溢或下溢时产生中断 */
TIM_UpdateRequestConfig(TIM2,TIM_UpdateSource_Global);
TIM_ClearFlag(TIM2, TIM_FLAG_Update);
}
/**
* @brief ms延时程序,1ms为一个单位
* @param
* [url=home.php?mod=space&uid=2817080]@ARG[/url] nTime: Delay_ms( 10 ) 则实现的延时为 10 * 1ms = 10ms
* @retval 无
*/
void Delay_ms(__IO uint32_t nTime)
{
/* 清零计数器并使能滴答定时器 */
TIM2->CNT = 0;
TIM_Cmd(TIM2, ENABLE);
for( ; nTime > 0 ; nTime--)
{
/* 等待一个延时单位的结束 */
while(TIM_GetFlagStatus(TIM2, TIM_FLAG_Update) != SET);
TIM_ClearFlag(TIM2, TIM_FLAG_Update);
}
TIM_Cmd(TIM2, DISABLE);
}
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