改变占空比，发现电机转速并没有变化

sky克西 · 发表于 2017-4-24 16:21:00

TIM输出pwm波控制电机，改变占空比，电机转速不变，感觉程序没啥问题啊
void TIM8_PWM_Init(u32 arr,u32 psc)
{

GPIO_InitTypeDef  GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
//使能时钟
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM8,ENABLE);    //TIM8时钟使能
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE); //使能时钟

//引脚复用映射

GPIO_PinAFConfig(GPIOC,GPIO_PinSource7,GPIO_AF_TIM8);

//初始化引脚
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;       //复用功能
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //速度100MHz
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;    //推挽复用输出
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;       //上拉
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;          //GPIOC7
GPIO_Init(GPIOC,&GPIO_InitStructure);             //初始化PC7

//定时器初始化
TIM_TimeBaseStructure.TIM_Prescaler=psc;  //定时器分频
TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up; //向上计数模式
TIM_TimeBaseStructure.TIM_Period=arr; //自动重装载值
TIM_TimeBaseStructure.TIM_ClockDivision=TIM_CKD_DIV1;
TIM_TimeBaseInit(TIM8,&TIM_TimeBaseStructure);//初始化定时器8

//初始化TIM8 Channel1234 PWM模式
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1; //选择定时器模式:TIM脉冲宽度调制模式2
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //比较输出使能
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low; //输出极性:TIM输出比较极性低

TIM_OC2Init(TIM8, &TIM_OCInitStructure);  //根据T指定的参数初始化外设TIM8OC2

TIM_OC2PreloadConfig(TIM8, TIM_OCPreload_Enable);  //使能TIM8在CCR2上的预装载寄存器

TIM_ARRPreloadConfig(TIM8,ENABLE);//ARPE使能

TIM_Cmd(TIM8, ENABLE);  //使能TIM8

}

int main(void)
{

TIM8_PWM_Init(1000,84-1);//84M/84=1Mhz的计数频率,重装载值1000，所以PWM频率为 1M/1000=1Khz.
      TIM_SetCompare2(TIM8,100);//？？从0-1000转速无变化

}