利用TIM1的通道1(PA8)产生PWM(频率1K,占空比50%),结果产生的PWM如附图,问题是:1、不管我怎么改TIM_Period和TIM_Prescaler,频率没有变化 2、改TIM_Pulse,占空比也没变化,但如果把它改为0,就没有波形了。求高手们指点,, 代码如下:
GPIO_InitTypeDef GPIO_InitStructure;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO,ENABLE);
GPIO_InitStructure.GPIO_Pin=GPIO_Pin_8;
GPIO_InitStructure.GPIO_Mode=GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;
GPIO_Init(GPIOA,&GPIO_InitStructure);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1,ENABLE);
TIM_BaseInitStructure.TIM_Period =199;
TIM_BaseInitStructure.TIM_Prescaler = 359;
TIM_BaseInitStructure.TIM_ClockDivision = 0;
TIM_BaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up; //向上计数模式
TIM_BaseInitStructure.TIM_RepetitionCounter = 0;
TIM_TimeBaseInit(TIM1, &TIM_BaseInitStructure);
TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1;
TIM_OCInitStructure.TIM_OutputState=TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;
TIM_OCInitStructure.TIM_Pulse=100;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;
TIM_OC1Init(TIM1,&TIM_OCInitStructure);
TIM_OC1PreloadConfig(TIM1,TIM_OCPreload_Enable);
TIM_ARRPreloadConfig(TIM1,ENABLE);
TIM_Cmd(TIM1, ENABLE); //TIM开启
TIM_CtrlPWMOutputs(TIM1 ,ENABLE ); //
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