系统时钟设置，如何改变系统时钟的频率，从36MHZ改到72MHZ

1194820783@qq.c · 发表于 2015-8-6 23:17:47

原子哥，在配置PWM波的时候我设置的72分频，自动重装载寄存器的值是2500，按理说应该是输出400HZ的PWM波，可实际输出了200HZ；定了2ms的定时器实际时间却是4ms；而且串口发送的都是乱码。感觉时钟是跑在36MHZ而不是72MHZ，我应该怎么改回72MHZ啊。。。求助原子哥。。。。。

TIM_TimeBaseStructure.TIM_Period = 2500-1;
TIM_TimeBaseStructure.TIM_Prescaler =72-1;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

TIM_ARRPreloadConfig(TIM3, ENABLE);

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_Pulse = CCR_Val;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

TIM_OC1Init(TIM3, &TIM_OCInitStructure);
TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);