STM32单片机如何产生PPM信号？

本代码实验环境为STM32F407,定时器主频为84Mhz:

TIM3_Int_Init(500-1,84-1);//定时器中断初始化

void TIM3_Int_Init(u16 arr,u16 psc)

{

TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;

NVIC_InitTypeDef NVIC_InitStructure;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3,ENABLE);  ///使能TIM3时钟

TIM_TimeBaseInitStructure.TIM_Period = arr; //自动重装载值

TIM_TimeBaseInitStructure.TIM_Prescaler=psc;  //定时器分频

TIM_TimeBaseInitStructure.TIM_CounterMode=TIM_CounterMode_Up; //向上计数模式

TIM_TimeBaseInitStructure.TIM_ClockDivision=TIM_CKD_DIV1; 

TIM_TimeBaseInit(TIM3,&TIM_TimeBaseInitStructure);//初始化TIM3

TIM_ITConfig(TIM3,TIM_IT_Update,ENABLE); //允许定时器3更新中断

TIM_Cmd(TIM3,ENABLE); //使能定时器3

NVIC_InitStructure.NVIC_IRQChannel=TIM3_IRQn; //定时器3中断

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=0x01; //抢占优先级1

NVIC_InitStructure.NVIC_IRQChannelSubPriority=0x03; //子优先级3

NVIC_InitStructure.NVIC_IRQChannelCmd=ENABLE;

NVIC_Init(&NVIC_InitStructure);

}