程序通俗易懂
#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
}