精准控制PWM脉冲的频率和数量

　　在一些项目中，我们经常要控制PWM脉冲的频率和数量，比如步进电机的控制等，下面分享一个程序是关于这方面的，程序的思想就是通过STM32的定时器来输出PWM波，并开启定时器中断，在中断里面计数脉冲的数量，一旦脉冲数量达到了目标值，就关闭定时器，实现精确控制脉冲的数量。

　　下面是程序分析：

　　定时器4配置

　　

#include"stm32f10x.h"
#include"pwm.h"
/*¶¨Ê±Æ÷4Êä³ö4·²»Í¬Õ¼¿Õ±ÈÂö³å
Ó²¼þÁ¬½ÓÈçÏÂ
CH1--PB6
CH2--PB7
CH3--PB8
CH4--PB9
*/
void PWM_Init(u16 arr,u16 psc)
{
u16 val1=arr/5;
/*u16 val2=arr/4;
u16 val3=arr/6;
u16 val4=arr/8;*/


GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;

//ʱÖÓÅäÖÃ
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4 ,ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB|RCC_APB2Periph_AFIO ,ENABLE);




//¶Ë¿Ú³õʼ»¯
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6|GPIO_Pin_7|GPIO_Pin_8|GPIO_Pin_9;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOB, &GPIO_InitStructure);

//¶¨Ê±Æ÷4»ù±¾ÅäÖÃ
TIM_TimeBaseInitStructure.TIM_Period=arr;
TIM_TimeBaseInitStructure.TIM_Prescaler=psc;
TIM_TimeBaseInitStructure.TIM_ClockDivision=0;
TIM_TimeBaseInitStructure.TIM_CounterMode=TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM4,&TIM_TimeBaseInitStructure);

//PWMģʽÅäÖÃ

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1; //Ñ¡Ôñ¶¨Ê±Æ÷ģʽ:TIMÂö³å¿í¶Èµ÷ÖÆģʽ1
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //±È½ÏÊä³öʹÄÜ
TIM_OCInitStructure.TIM_Pulse = 0; //ÉèÖôý×°È벶»ñ±È½Ï¼Ä´æÆ÷µÄÂö³åÖµ
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //Êä³ö¼«ÐÔ:TIMÊä³ö±È½Ï¼«ÐÔ¸ß
TIM_OC1Init(TIM4, &TIM_OCInitStructure);
TIM_OC1PreloadConfig(TIM4, TIM_OCPreload_Enable); //ʹÄÜTIMxÔÚCCR1ÉϵÄԤװÔؼĴæÆ÷

/*TIM_OCInitStructure.TIM_Pulse=val2;
TIM_OC2Init(TIM4,&TIM_OCInitStructure);
TIM_OC2PreloadConfig(TIM4,TIM_OCPreload_Enable );

TIM_OCInitStructure.TIM_Pulse=val3;
TIM_OC3Init(TIM4,&TIM_OCInitStructure);
TIM_OC3PreloadConfig(TIM4,TIM_OCPreload_Enable );

TIM_OCInitStructure.TIM_Pulse=val4;
TIM_OC4Init(TIM4,&TIM_OCInitStructure);
TIM_OC4PreloadConfig(TIM4,TIM_OCPreload_Enable );*/


TIM_ARRPreloadConfig(TIM4, ENABLE);

TIM_ClearITPendingBit(TIM4, TIM_IT_CC1);
TIM_ITConfig(TIM4,TIM_IT_CC1,ENABLE);

//TIM_Cmd(TIM4,ENABLE);

}
void NVIC_Config(void)
{
NVIC_InitTypeDef NVIC_InitStructure;
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQn ;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);

}

　　主函数：

#include "stm32f10x.h"
#include "led.h"
#include "delay.h"
#include "pwm.h"
#include "usart.h"
u32 step=0;
int main(void)
{
SystemInit();
uart_init(115200);
delay_init();
LED_Init();
NVIC_Config();
PWM_Init(719,100);
TIM_Cmd(TIM4,ENABLE);
while(1)
{

// delay_ms(100);
// LED1=!LED1;
// delay_ms(100);
TIM4->CCR1 = 300;

}
}
void TIM4_IRQHandler(void)
{
if(TIM_GetITStatus(TIM4,TIM_IT_CC1)!=RESET)
{
TIM_ClearITPendingBit(TIM4,TIM_IT_CC1);
step++;
printf("%d\r\n",step);
if(step==80000)
{
TIM_Cmd(TIM4,DISABLE);
}
}

}

以上就是完整程序。欢迎同学交流，改正。