這個暑假沒有回家，在學校準備九月份的電子設計競賽。今天想給大家分享一下STM32高階定時器輸出PWM波驅動直流電機的問題。。

       要想用定時器輸出的PWM控制直流電機，，首先要理解“通道”的概念。。一個定時器可以支援一個PWM，要支援多個，就需要各路PWM週期相同而佔空比不同。。利用定時器的通道這一概念就可以實現。STM32微控制器定時器有四個通道，每個通道的TIM1——CCRx（x=1、2、3、4）存放一個值。。計數器從0開始計數，此時PWM輸出為0。。當計數值達到寄存值時，此時PWM電平發生翻轉，輸出1。。所以設定四個不同的佔空比的值，就可以產生四路PWM波。

      本例程使用高階定時器TIM1輸出兩路PWM波分別控制左邊兩個輪子輪和右邊兩個輪子。TIM1時鐘頻率是72MHz，如果要輸出20KHz的PWM波，，應該把TIM1_Period設為3600-1。具體程式碼如下所示：

void TIM_Configuration(vu16 CCR1,vu16 CCR2)
{

     TIM1_TimeBaseInitTypeDef  TIM1_TimeBaseStructure;
    TIM1_OCInitTypeDef  TIM1_OCInitStructure;

   TIM1_CtrlPWMOutputs(DISABLE);
  /* TIM1 Peripheral Configuration */
  TIM1_DeInit();

  /* Time Base configuration */
  TIM1_TimeBaseStructure.TIM1_Prescaler = 0;
  TIM1_TimeBaseStructure.TIM1_CounterMode = TIM1_CounterMode_Up;
  TIM1_TimeBaseStructure.TIM1_Period = 3599;
  TIM1_TimeBaseStructure.TIM1_ClockDivision = 0;
  TIM1_TimeBaseStructure.TIM1_RepetitionCounter = 0;

  TIM1_TimeBaseInit(&TIM1_TimeBaseStructure);

  /* Channel 1, 2,3 and 4 Configuration in PWM mode */
  TIM1_OCInitStructure.TIM1_OCMode = TIM1_OCMode_PWM2; 

  TIM1_OCInitStructure.TIM1_OutputState = TIM1_OutputState_Enable;
  TIM1_OCInitStructure.TIM1_OutputNState = TIM1_OutputNState_Enable;                 
  TIM1_OCInitStructure.TIM1_Pulse = CCR1;
  TIM1_OCInitStructure.TIM1_OCPolarity = TIM1_OCPolarity_Low;
  TIM1_OCInitStructure.TIM1_OCNPolarity = TIM1_OCNPolarity_Low;        
  TIM1_OCInitStructure.TIM1_OCIdleState = TIM1_OCIdleState_Set;
  TIM1_OCInitStructure.TIM1_OCNIdleState = TIM1_OCIdleState_Reset;         
 
  TIM1_OC1Init(&TIM1_OCInitStructure);

  TIM1_OCInitStructure.TIM1_Pulse = CCR2;
  TIM1_OC2Init(&TIM1_OCInitStructure);

  /* TIM1 counter enable */
  TIM1_Cmd(ENABLE);

  /* Main Output Enable */
  TIM1_CtrlPWMOutputs(ENABLE);

}

   最後可以呼叫這個函式實現小車的前進，後退，左轉，右轉。。好的，，今天就寫到這裡，希望地大家有用。。