因为前段时间需要用STM32F103控制步进电机，所以写了了可用于控住GPIO口输出固定数量脉冲的函数，可直接输入脉冲数，并且可以调节PWM的频率（每个脉冲的周期）。
	参考了网上大神的指导，我的思路是：用两个定时器（一个用于PWM输出，一个用于中断PWM输出），通过对PWM的周期和输出时间的控制，来达到输出固定脉冲数的目的。
	下面为主要代码：

#include <sys.h>
#include <pwn.h>
#include <interrupt.h>
#include <step.h>
//输出固定脉冲数量
//speed为输出脉冲的频率
//pulse为输出脉冲数量
//在调脉冲频率时，需同时调x
void pulse_putput(u16 speed, u16 pulse)
{ 
 	TIM2_init(pulse*10);       //设置脉冲数量（10为speed/100)
	TIM_Cmd(TIM2, ENABLE);            //使能TIM4
	TIM_ClearITPendingBit(TIM2, TIM_IT_Update);         //清除中断标志位
	TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);          //使能更新中断
	
	TIM3_PWM_Init(speed);                                 //设置PWM输出的频率
	
	TIM_Cmd(TIM3, ENABLE);             //使能定时器3 
                   
}

然后就是PWM的初始化代码(这一段是基础的PWM初始化）

//TIM3 PWN²¿·Ö³õʼ»¯
//PWNÊä³ö³õʼ»¯
//arr: ×Ô¶¯ÖØ×°ÔØ
//psc: ʱÖÓÔ¤·ÖƵ
void TIM3_PWM_Init(u16 arr)
{ 
	GPIO_InitTypeDef GPIO_InitStructure;
	TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
	TIM_OCInitTypeDef TIM_OCInitStructure;
	
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);       //ʹÄܶ¨Ê±Æ÷3ʱÖÓ
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB|RCC_APB2Periph_AFIO, ENABLE);
	
	GPIO_PinRemapConfig(GPIO_PartialRemap_TIM3, ENABLE);     //ÖØÓ³ÉäTIM3_CH2->PB5
	
	//ÉèÖøÃÒý½ÅΪ¸´ÓÃÊä³ö¹¦ÄÜ£¬Êä³öTIM3 CH2µÄPWNÂö³å²¨ÐÎ GPIOB.5
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;  //TIM_CH2
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;       //¸´ÓÃÍÆÍìÊä³ö
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_Init(GPIOB, &GPIO_InitStructure);            //³õʼ»¯GPIO
	
	//³õʼ»¯TIM3
	TIM_TimeBaseStructure.TIM_Period = arr-1;      //ÉèÖÃÔÚ×Ô¶¯ÖØ×°ÔØÖÜÆÚÖµ
	TIM_TimeBaseStructure.TIM_Prescaler = 71;     //ÉèÖÃÔ¤·ÖƵֵ
	TIM_TimeBaseStructure.TIM_ClockDivision = 0;   //ÉèÖÃʱÖӷָTDTS = Tck_tiim
	TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;    //TIMÏòÉϼÆÊýģʽ
	TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);     //³õʼ»¯TIMx
	
	//³õʼ»¯TIM3 Channel2 PWNģʽ
	TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;       //Ñ¡ÔñPWNģʽ2
	TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;   //±È½ÏÊä³ö
	TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;       //Êä³ö¼«ÐÔ¸ß
	TIM_OC2Init(TIM3, &TIM_OCInitStructure);                        //³õʼ»¯ÍâÉèTIM3 OC2
	
	TIM_SelectMasterSlaveMode(TIM3, TIM_MasterSlaveMode_Enable);
	TIM_SelectOutputTrigger(TIM4, TIM_TRGOSource_Update);
	
	TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);           //ʹÄÜԤװÔؼĴæÆ÷
	
	TIM_SetCompare2(TIM3, arr/4);
	TIM_Cmd(TIM3, ENABLE);                           //ʹÄÜTIM3
	
	
}

定时器中断初始化

#include <interrupt.h>
#include "sys.h"


//通用定时器2中断初始化
void TIM2_init(u16 arr)
{ 
	TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
	NVIC_InitTypeDef NVIC_InitStructure;
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
	
	//定时器TIM2初始化
	TIM_TimeBaseStructure.TIM_Period = arr-1;
	TIM_TimeBaseStructure.TIM_Prescaler = 7200-1;
	TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
	TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
	TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
	
	TIM_SelectInputTrigger(TIM2, TIM_TS_ITR0);
	TIM_ITConfig(TIM2, TIM_IT_Update, DISABLE);
	
	//中断优先级设置
	NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
	NVIC_Init(&NVIC_InitStructure);
	
	TIM_Cmd(TIM2, ENABLE);
	
}
//定时器2中断服务程序
void TIM2_IRQHandler(void)
{ 

	if(TIM_GetITStatus(TIM2, TIM_IT_Update) != RESET)
	{ 

		TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
		TIM_CtrlPWMOutputs(TIM3, DISABLE);
		TIM_Cmd(TIM3, DISABLE);
		TIM_Cmd(TIM2, DISABLE);
		TIM_ITConfig(TIM2, TIM_IT_Update, DISABLE);

	}
}

程序的思维图如下
仅为个人拙见！

献上工程文件（KEIL,STM32F103VET6芯片）

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本人为新手，有不对的地方欢迎指正！

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