产生驱动电机的PWM波

通过定时器4产生频率为2k，占空比为50%的PWM波。
定时器的设置如下：
void TIM4_Mode_Config(u16 m,u16 n)
{
TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
TIM_OCInitTypeDef  TIM_OCInitStructure;
// u16 CCR1_Val = 500;        
  /* Time base configuration */   
  TIM_TimeBaseStructure.TIM_Period = m;       //μ±?¨ê±?÷′ó0??êyμ?999￡??′?a1000′?￡??aò????¨ê±?ü?ú
  TIM_TimeBaseStructure.TIM_Prescaler = 0;     //éè???¤·??μ￡o2??¤·??μ￡??′?a72MHz
  TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_div1 ; //éè??ê±?ó·??μ?μêy￡o2?·??μ
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Down;  //?òé???êy?￡ê?
  TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure);
  /* PWM1 Mode configuration: Channel1 */
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = n;    //éè??ì?±??μ￡?μ±??êy?÷??êyμ??a???μê±￡?μ???·￠éúì?±?
   

  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;     //?????aPWM?￡ê?1
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;  //μ±?¨ê±?÷??êy?μD?óúCCR1_Valê±?a??μ???
TIM_OC2Init(TIM4, &TIM_OCInitStructure);  //ê1?üí¨μà1
  TIM_OC2PreloadConfig(TIM4, TIM_OCPreload_Enable);
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;     //?????aPWM?￡ê?1
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;  //μ±?¨ê±?÷??êy?μD?óúCCR1_Valê±?a??μ???
  TIM_OC1Init(TIM4, &TIM_OCInitStructure);  //ê1?üí¨μà1
  TIM_OC1PreloadConfig(TIM4, TIM_OCPreload_Enable);
  TIM_ARRPreloadConfig(TIM4, ENABLE);    // ê1?üTIM4??????′??÷ARR
  /* TIM3 enable counter */
  TIM_Cmd(TIM4, ENABLE);                   //ê1?ü?¨ê±?÷4
}
仿真波形如下所述：