- #include<stm32f10x.h>
- void TIM3_PWM_Init(u16 arr,u16 psc);
- //1ms延时函数(72MHz)
- void delay_nms(u16 time)
- {
- u16 i=0;
- while(time--)
- {
- i=12000;
- while(i--);
- }
- }
- int main(void)
- {
- u16 TIMpulse=0;
- u8 dir=1;
- //TIM3_PWM_Init(899,0);//不分频，PWM频率=72000/900=80khz
- TIM3_PWM_Init(999,61999);//1HZ,
- delay_nms(100);//观察初始化的pwm
- // TIM_SetCompare2(TIM3,200);//占空比200/999+1=20%
- while(1)
- {
- if(dir)TIMpulse++;
- else TIMpulse--;
- if(TIMpulse>999)dir=0;
- if(TIMpulse==0)dir=1;
- TIM_SetCompare2(TIM3,TIMpulse);//程序中修改占空比TIMpulse/arr
- ;
- }
- }
- //arr:自动装载值 psc:预分频数
- //TIM3 PWM部分初始化
- void TIM3_PWM_Init(u16 arr,u16 psc)
- {
- GPIO_InitTypeDef GPIO_InitStructure;
- TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
- TIM_OCInitTypeDef TIM_OCInitStructure;
-
- RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3,ENABLE);
- RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB|RCC_APB2Periph_AFIO,ENABLE);//开启重映射时钟
-
- GPIO_PinRemapConfig(GPIO_PartialRemap_TIM3,ENABLE);//重映射TIM3_CH2到PB5输出
-
- //GPIO设置为复用输出，输出TIM3的CH2的PWM脉冲波形GPIOB5
- GPIO_InitStructure.GPIO_Mode=GPIO_Mode_AF_PP;
- GPIO_InitStructure.GPIO_Pin=GPIO_Pin_5;
- GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;
- GPIO_Init(GPIOB,&GPIO_InitStructure);
-
- //初始化TIM3
- TIM_TimeBaseStructure.TIM_Period=arr; //设置自动重装载周期值(决定PWM的频率)
- TIM_TimeBaseStructure.TIM_Prescaler=psc; //预分频值
- TIM_TimeBaseStructure.TIM_ClockDivision=0; //设置时钟分割：TDTS=Tck_tim
- TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up;//向上计数
- TIM_TimeBaseInit(TIM3,&TIM_TimeBaseStructure);
-
- //初始化TIM3 Channel2 PWM模式
- TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM2; //选择PWM模式2，计数值大于比较值有效
- TIM_OCInitStructure.TIM_OutputState=TIM_OutputState_Enable; //比较输出使能
- TIM_OCInitStructure.TIM_OCPolarity=TIM_OCPolarity_High; //输出极性 高为有效值
- //配置占空比 500/arr重载计数器=500/999+1，，和函数TIM_SetCompare2(TIM3,TIMpulse);功能一样
- TIM_OCInitStructure.TIM_Pulse=500;
- TIM_OC2Init(TIM3,&TIM_OCInitStructure); //初始化外设TIM3 OC2通道
- TIM_OC2PreloadConfig(TIM3,TIM_OCPreload_Enable); //使能预装载器即TIM3_CCR2的预装载值在更新事件到来时才能被传送至当前寄存器中
-
- TIM_Cmd(TIM3,ENABLE); //使能TIM3
- }
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