刚开始的时候，发送完一个指令后，pwm波依旧在发送。后来我改成每发完一次就把pwm停掉了。然后这个时候发送的距离就非常近。
在示波器上看波形。感觉不对，应为默认电平是低的。就是配置完后是A的波形。但是正确的波形应该是B的波形才对啊。
我程序如下，能否看下有什么地方不对。
- GPIO_InitTypeDef GPIO_InitStructure;
- TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
- TIM_OCInitTypeDef TIM_OCInitStructure;
- NVIC_InitTypeDef NVIC_InitStructure;
- GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
- GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
- GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
- GPIO_Init(GPIOA, &GPIO_InitStructure);
-
- TIM_TimeBaseStructure.TIM_Period = 26 - 1;
- TIM_TimeBaseStructure.TIM_Prescaler = 72 - 1;
- TIM_TimeBaseStructure.TIM_ClockDivision = 0;
- TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Down;
- TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
- TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
- TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
- TIM_OCInitStructure.TIM_Pulse = 13;
- TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
- TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Reset;
- TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCNIdleState_Reset;
- TIM_OC3Init(TIM2, &TIM_OCInitStructure);
-
- TIM_OC3PreloadConfig(TIM2, TIM_OCPreload_Enable);
- TIM_ARRPreloadConfig(TIM2, ENABLE);
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