一、初始化GPIO

使用PB1,查芯片手册对应TIM3_CH4

        GPIO_InitTypeDef GPIO_InitStructure;

        RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);

        RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3,ENABLE);

        GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1;

        GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;

        GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

        GPIO_Init(GPIOB, &GPIO_InitStructure);

二、初始化TIM和PWM

　　 TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

    TIM_OCInitTypeDef TIM_OCInitStructure;

    /* 周期1000 */

    TIM_TimeBaseStructure.TIM_Period = ;

    /* 定时器时间间隔1微秒 */

    TIM_TimeBaseStructure.TIM_Prescaler = ;

    TIM_TimeBaseStructure.TIM_ClockDivision = ;

    /* 向上计数 */

    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

    /* 配置 */

    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

    /* 选择PWM1模式 */

    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;

    /* 允许输出模式 */

    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;

    /* 匹配值 */

    TIM_OCInitStructure.TIM_Pulse = ;

    /* 设置小于匹配值时为高电平 */

    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

    /* 使能通道1 */

    TIM_OC4Init(TIM3, &TIM_OCInitStructure);    

    TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Enable);

    TIM_ARRPreloadConfig(TIM3, ENABLE);

    TIM_Cmd(TIM3, ENABLE); 

三、main函数部分

通过修改CCRx寄存器，改变占空比。从而调整电流大小

     while()

    {

            if(CCR3_Val >= && CCR3_Val <= )

            {

                CCR3_Val -= ;

                Delay();

            }

            else

            {

                CCR3_Val = ;

                Delay();

            }

            TIM3->CCR4 = CCR3_Val;

            Delay();

    }

PWM输出，呼吸灯的相关教程结束。