void RCC_Configuration(void)
{
RCC_DeInit();
RCC_HSEConfig(RCC_HSE_ON);
/* Wait till HSE is ready */
HSEStartUpStatus = RCC_WaitForHSEStartUp();
if(HSEStartUpStatus == SUCCESS)
{
/* Enable Prefetch Buffer */
FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
/* Flash 2 wait state */
FLASH_SetLatency(FLASH_Latency_2);
/* HCLK = SYSCLK */
RCC_HCLKConfig(RCC_SYSCLK_Div1);
/* PCLK2 = HCLK */
RCC_PCLK2Config(RCC_HCLK_Div1);
/* PCLK1 = HCLK/2 */
RCC_PCLK1Config(RCC_HCLK_Div2);
/* PLLCLK = 8MHz * 9 = 72 MHz */
RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9);
/* 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)
{
}
}
/* TIM2 clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
/* Enable USART1, GPIOA, GPIOA and AFIO clocks */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);
}
void TIM2_config(void)
{
/* Time base configuration*/
TIM_TimeBaseStructure.TIM_Period = 0xffff;//周期值 TIM_TimeBaseStructure.TIM_Prescaler = 0;//时钟的预分频数
TIM_TimeBaseStructure.TIM_ClockDivision = 0;//TIM配置时钟分割 TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;//向上计数
TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
/* Prescaler configuration [配置TIM的预分频数]*/
TIM_PrescalerConfig(TIM2, 36, TIM_PSCReloadMode_Immediate);//TIM2,36分频，预分频数立即载入
/* Output Compare Timing Mode configuration: Channel1 [配置输出比较模式]*/
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Timing;//TIM输出比较计时模式
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;//输出允许
TIM_OCInitStructure.TIM_Pulse = 1000;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;//极性HIGH
TIM_OC1Init(TIM2, &TIM_OCInitStructure);
TIM_OC1PreloadConfig(TIM2, TIM_OCPreload_Disable);//关闭TIM2在CCR1寄存器上的预载入寄存器
/* TIM IT enable [使能TIM2比较中断]*/
TIM_ITConfig(TIM2, TIM_IT_CC1, ENABLE);
/* TIM2 enable counter */
TIM_Cmd(TIM2, ENABLE);
}
定时器2定了多长时间呢？怎样计算的呢？ |
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