以上在设置MAPR的[26:24]位的时候，我们先把这几位清空，然后在置位这几个位。这样，才不会影响之前对AFIO->
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
TIM_OCInitStructure.TIM_Channel = TIM_Channel_1;
TIM_OCInitStructure.TIM_Pulse = CCR1_Val;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
TIM_OCInit(TIM3, &TIM_OCInitStructure);
启用CCR1寄存器的影子寄存器（直到产生更新事件才更改设置）
TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);
TIM_OCInitStructure.TIM_Channel = TIM_Channel_2;
TIM_OCInitStructure.TIM_Pulse = CCR2_Val;
TIM_OCInit(TIM3, &TIM_OCInitStructure);
TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);
TIM_OCInitStructure.TIM_Channel = TIM_Channel_3;
TIM_OCInitStructure.TIM_Pulse = CCR3_Val;
TIM_OCInit(TIM3, &TIM_OCInitStructure);
TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Enable);
TIM_OCInitStructure.TIM_Channel = TIM_Channel_4;
TIM_OCInitStructure.TIM_Pulse = CCR4_Val;
TIM_OCInit(TIM3, &TIM_OCInitStructure);
TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Enable);
TIM_ARRPreloadConfig(TIM3, ENABLE);
TIM_Cmd(TIM3, ENABLE);
while (1)
{
}
}
