请教STM32产生PWM问题？

只看该作者 · 2013-7-27 10:31

/*TIM1时钟配置*/
TIM_TimeBaseStructure.TIM_Prescaler = 4000;                                              //预分频(时钟分频)72M/4000=18K
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;             //向上计数
TIM_TimeBaseStructure.TIM_Period = 144;                                                       //装载值 18k/144=125hz
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseStructure.TIM_RepetitionCounter = 0x0;
TIM_TimeBaseInit(TIM1,&TIM_TimeBaseStructure);

/* Channel 1 Configuration in PWM mode */
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;                               //PWM模式2
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;       //正向通道有效
TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Disable;//反向通道无效
TIM_OCInitStructure.TIM_Pulse = 40;                //占空时间
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;                //输出极性
TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;    //互补端的极性
TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;
TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;

TIM_OC1Init(TIM1,&TIM_OCInitStructure);                                              //通道1
请问在以上配置中TIM_TimeBaseStructure.TIM_Period = 144;和TIM_OCInitStructure.TIM_Pulse = 40; 有什么关系，而且我始终不理解TIM_OCInitStructure.TIM_Pulse = 40; 是占空时间，为什么说是占空时间呢？