GPIO配置：
void GPIO_config(void){GPIO_InitTypeDefGPIO_InitStructure;RCC_APB1PeriphClockCmd( RCC_APB1Periph_TIM3 | RCC_APB1Periph_TIM4, ENABLE);//使能TIM3 | TIM4时钟RCC_APB2PeriphClockCmd( RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE); //使能GPIOA时钟GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6; //TIM3-CH1: PA6GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; //复用推挽输出GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //指定输出速率最大为50MHzGPIO_Init(GPIOA, &GPIO_InitStructure);//初始化GPIO口}
主定时器配置----配置PWM脉冲频率和占空比：
/*--------主定时器配置--------*/void TIM3_Config(u32 Freq, u8 DutyCycle){u16 ARR;//声明变量ARR -- 自动重装值u16 PSC = 1; //声明变量PSC并赋初值PSC=1, 预分频系数u16 CCR;//声明变量CCR -- 输出捕获寄存器脉冲值TIM_TimeBaseInitTypeDefTIM_TimeBaseStructure; //定义定时器初始化结构体TIM_OCInitTypeDef TIM_OCInitStructure;//定义定时器输出配置结构体/*--------根据PWM脉冲频率设定定时器时钟的预分频系数--------*/while(SystemCoreClock/PSC/Freq>65535)//当自动重装值大于65535时，预分频系数加1{PSC++;}ARR = SystemCoreClock/PSC/Freq; //根据频率Freq以及TIME时钟的预分频值PSC计算自动重装载值/*---------定时器初始化配置---------*/TIM_TimeBaseStructure.TIM_Period = (ARR - 1); //指定在下一次更新事件时要加载到活动自动重载寄存器中的周期值TIM_TimeBaseStructure.TIM_Prescaler = (PSC - 1); //指定用于分频 TIME 时钟的预分频器值TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //指定时钟分频，不分频TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //指定计数模式，向上计数TIM_TimeBaseInit( TIM3, &TIM_TimeBaseStructure); //初始化TIM3/*--------定时器输出配置--------*/ TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1; // 设置工作模式是PWM，且为PWM1工作模式，TIMx_CNT<TIMx_CCR1时为高电平TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; // 也就是使能PWM输出到端口TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;// 输出极性，低电平有效CCR = ARR * (100 - DutyCycle) /100;TIM_OCInitStructure.TIM_Pulse = CCR ;//设置待装入捕获寄存器的脉冲值TIM_OC1Init( TIM3, &TIM_OCInitStructure); //初始化 TIM3-OC1TIM_SelectMasterSlaveMode( TIM3, TIM_MasterSlaveMode_Enable); //定时器主从模式使能TIM_SelectOutputTrigger( TIM3, TIM_TRGOSource_Update); //选择触发方式：使用更新事件作为触发输出TIM_OC1PreloadConfig( TIM3, TIM_OCPreload_Enable); //TIM3-CH1预装载使能TIM_ARRPreloadConfig( TIM3, ENABLE);//使能ARR预装载寄存器}
从定时器配置----配置PWM脉冲数量：
/*-------- 从定时器配置 --------*/void TIM4_Config(u16 PulseNum){TIM_TimeBaseInitTypeDefTIM_TimeBaseStructure;NVIC_InitTypeDefNVIC_InitStructure;TIM_TimeBaseStructure.TIM_Period = PulseNum; //设定脉冲个数TIM_TimeBaseStructure.TIM_Prescaler = 0; //不分频TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //指定时钟分频，不分频TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //向上计数TIM_TimeBaseInit( TIM4, &TIM_TimeBaseStructure);TIM_SelectInputTrigger( TIM4, TIM_TS_ITR2); // TIM3-主，TIM4-从 ITR2TIM_SelectSlaveMode( TIM4,TIM_SlaveMode_External1 );// TIM4从模式，选择触发器（TRGI）的上升沿为计数器提供时钟TIM_ITConfig( TIM4, TIM_IT_Update, DISABLE); // 禁用TIM4更新中断NVIC_PriorityGroupConfig(NVIC_PriorityGroup_3);//中断组别：3NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQn;NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 3;NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;NVIC_Init(&NVIC_InitStructure);}
PWM脉冲函数配置：
void PWM_Output(u32 Freq, u8 DutyCycle, u16 PulseNum) {TIM4_Config(PulseNum);TIM_Cmd( TIM4, ENABLE);TIM_ClearITPendingBit( TIM4, TIM_IT_Update);TIM_ITConfig( TIM4, TIM_IT_Update, ENABLE);TIM3_Config(Freq, DutyCycle);TIM_Cmd( TIM3, ENABLE);}
中断程序配置：
void TIM4_IRQHandler(void){if (TIM_GetITStatus( TIM4, TIM_IT_Update) != RESET){TIM_ClearITPendingBit( TIM4, TIM_IT_Update);// 清除中断标志位TIM_Cmd( TIM3, DISABLE);// 关闭定时器3TIM_Cmd( TIM4, DISABLE);// 关闭定时器4TIM_ITConfig( TIM4, TIM_IT_Update, DISABLE);}}
主函数部分：
#include "delay.h"#include "timer.h"int main(void){delay_init(); //延时函数初始化GPIO_config();while(1){PWM_Output(250000,50,2); //频率：250kHz；占空比：50%； 脉冲数量 2；delay_us(2000);}}
头文件内容：
#ifndef __TIMER_H#define __TIMER_H#include "sys.h"/** 接口函数**/void GPIO_config(void);void TIM3_ConfigTIM3_Config(u32 Freq, u8 DutyCycle);void TIM4_Config(u16 PulseNum);void PWM_Output(u32 Freq, u8 DutyCycle, u16 PulseNum);#endif
运行结果：
经测试：250kHz以下，上述配置可实现精确控制PWM脉冲个数，超过250kHz，脉冲个数异常
测试芯片：STM32F103ZET6
