例程（6）
This example shows how to use the TIM peripheral to measure the frequency and
duty cycle of an external signal.
The TIMxCLK frequency is set to 72 MHz, the Prescaler is 0 so the TIM2 counter
clock is 72 MHz. so the minimum frequency value to measure is 1100 Hz.
TIM2 is configured in PWM Input Mode: the external signal is connected to
TIM2 Channel2 used as input pin.
To measure the frequency and the duty cycle we use the TIM2 CC2 interrupt request,
so In the TIM2_IRQHandler routine, the frequency and the duty cycle of the external
signal are computed.
The "Frequency" variable contains the external signal frequency:
Frequency = TIM2 counter clock / TIM2_CCR2 in Hz,
The "Duty_Cycle" variable contains the external signal duty cycle:
Duty_Cycle = (TIM2_CCR1*100)/(TIM2_CCR2) in %.
/* Includes ------------------------------------------------------------------*/
#include "stm32f10x_lib.h"
/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_ICInitTypeDef TIM_ICInitStructure;
ErrorStatus HSEStartUpStatus;
/* Private function prototypes -----------------------------------------------*/
void RCC_Configuration(void);
void GPIO_Configuration(void);
void NVIC_Configuration(void);
/* Private functions ---------------------------------------------------------*/
/*******************************************************************************
* Function Name : main
* Description : Main program
* Input : None
* Output : None
* Return : None
*******************************************************************************/
int main(void)
{
#ifdef DEBUG
debug();
#endif
/* System Clocks Configuration */
RCC_Configuration();
/* NVIC configuration */
NVIC_Configuration();
/* Configure the GPIO ports */
GPIO_Configuration();
/* TIM2 configuration: PWM Input mode ------------------------
The external signal is connected to TIM2 CH2 pin (PA.01),
The Rising edge is used as active edge,
The TIM2 CCR2 is used to compute the frequency value
The TIM2 CCR1 is used to compute the duty cycle value
------------------------------------------------------------ */
TIM_ICInitStructure.TIM_ICMode = TIM_ICMode_PWMI; // TIM使用输入PWM模式
TIM_ICInitStructure.TIM_Channel = TIM_Channel_2;
TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising; // TIM输入捕获上升沿
TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
//TIM输入2选择对应地与IIC2相连
TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
//TIM捕获在捕获输入上每探测到一个边沿执行一次
TIM_ICInitStructure.TIM_ICFilter = 0x0;//选择输入比较滤波器
TIM_ICInit(TIM2, &TIM_ICInitStructure);
//根据TIM_ICInitStruct中指定的参数初始化外设TIM2
/* Select the TIM2 Input Trigger: TI2FP2 */
TIM_SelectInputTrigger(TIM2, TIM_TS_TI2FP2);
//选择TIM2输入触发源---TIM经滤波定时器输入2
/* Select the slave Mode: Reset Mode */
TIM_SelectSlaveMode(TIM2, TIM_SlaveMode_Reset);
//选择TIM2从模式----选中触发信号（TRGI）的上升沿初始化计数器并更新触发寄存器
/* Enable the Master/Slave Mode */
TIM_SelectMasterSlaveMode(TIM2, TIM_MasterSlaveMode_Enable);//TIM主/从模式使能
/* TIM enable counter */
TIM_Cmd(TIM2, ENABLE);
/* Enable the CC2 Interrupt Request */
TIM_ITConfig(TIM2, TIM_IT_CC2, ENABLE);
while (1);
}
/*******************************************************************************
* Function Name : RCC_Configuration
* Description : Configures the different system clocks.
* Input : None
* Output : None
* Return : None
*******************************************************************************/
void RCC_Configuration(void)
{
/* RCC system reset(for debug purpose) */
RCC_DeInit();
/* Enable HSE */
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);
/* GPIOA clock enable */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
}
/*******************************************************************************
* Function Name : GPIO_Configuration
* Description : Configure the GPIOD Pins.
* Input : None
* Output : None
* Return : None
*******************************************************************************/
void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
/* GPIOA Configuration */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);
}
/*******************************************************************************
* Function Name : NVIC_Configuration
* Description : Configure the nested vectored interrupt controller.
* Input : None
* Output : None
* Return : None
*******************************************************************************/
void NVIC_Configuration(void)
{
NVIC_InitTypeDef NVIC_InitStructure;
#ifdef VECT_TAB_RAM
/* Set the Vector Table base location at 0x20000000 */
NVIC_SetVectorTable(NVIC_VectTab_RAM, 0x0);
#else /* VECT_TAB_FLASH */
/* Set the Vector Table base location at 0x08000000 */
NVIC_SetVectorTable(NVIC_VectTab_FLASH, 0x0);
#endif
/* Enable the TIM2 global Interrupt */
NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQChannel;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
#ifdef DEBUG
/*******************************************************************************
* Function Name : assert_failed
* Description : Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* Input : - file: pointer to the source file name
* - line: assert_param error line source number
* Output : None
* Return : None
*******************************************************************************/
void assert_failed(u8* file, u32 line)
{
/* User can add his own implementation to report the file name and line number,
ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
while (1)
{
}
}
#endif
在stm32f10x_it.c中，中断设置如下 ：
void TIM2_IRQHandler(void)
{
/*
The "Frequency" variable contains the external signal frequency:
Frequency = TIM2 counter clock / TIM2_CCR2 in Hz,
The "Duty_Cycle" variable contains the external signal duty cycle:
Duty_Cycle = (TIM2_CCR1*100)/(TIM2_CCR2) in %.
*/
/* Clear TIM2 Capture compare interrupt pending bit */
TIM_ClearITPendingBit(TIM2, TIM_IT_CC2);
/* Get the Input Capture value */
IC2_Value = TIM_GetCapture2(TIM2);
if(IC2_Value != 0)
{
/* Duty cycle computation */
Duty_Cycle = (TIM_GetCapture1(TIM2) * 100) / IC2_Value;
/* Frequency computation */
Frequency = 72000000 / IC2_Value;
}
else
{
Duty_Cycle = 0;
Frequency = 0;
}
}
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