STM32PWM调制问题

只看该作者 · 2012-1-11 17:04

哪位用过PWM，现在有个奇怪的现象，用PWM控制电机，第一次发485命令，输出高电平，并没有输出有占空比的波形，第二次再发相同命令，可以输出PWM脉冲

只看该作者 · 2012-1-11 17:06

代码如下：
void TIM_Configuration()
{
  TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
  TIM_TimeBaseStructure.TIM_Period = 200; //
  TIM_TimeBaseStructure.TIM_Prescaler = 7199; //
  TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
  TIM_TimeBaseInit(TIM3,&TIM_TimeBaseStructure);
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1; //PWM模式1输出
  TIM_OCInitStructure.TIM_Pulse = Duty;//占空比=(CCRx/ARR)*100%
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High ;//TIM输出比较极性高
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;//使能输出状态
  TIM_Cmd(TIM3, ENABLE);
}
  Duty = 90;
  TIM_PWMConfiguration();
  TIM_OC1Init(TIM3, &TIM_OCInitStructure);//TIM3的CH1输出
  TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);