各位大神，stm32ppm解码程序有些看不懂，求注释

caesar1994

#include "PPM.h"fficeffice" />

#include "stm32f10x.h"

 

TIM_ICInitTypeDef  TIM_ICInitStructure;

void PM_Init(void)

{

GPIO_InitTypeDef GPIO_InitStructure;

NVIC_InitTypeDef NVIC_InitStructure;

TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;

 

/* TIM3 clock enable */

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);

 

/* GPIOC clock enable */

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);

 

/* TIM3 chennel2 configuration: A.01 */

GPIO_InitStructure.GPIO_Pin   = GPIO_Pin_6 | GPIO_Pin_7 | GPIO_Pin_8 | GPIO_Pin_9 ;

GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_IN_FLOATING;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_Init(GPIOC, &GPIO_InitStructure);

GPIO_PinRemapConfig(GPIO_FullRemap_TIM3, ENABLE);

 

/* Enable the TIM3 global Interrupt */

NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;

  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;

  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

NVIC_Init(&NVIC_InitStructure);

 

 

TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);

 

TIM_TimeBaseStructure.TIM_Prescaler   = (72 - 1);

TIM_TimeBaseStructure.TIM_Period      = 0xffff;

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

 

TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

 

 

 

TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;

TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;

TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;

TIM_ICInitStructure.TIM_ICFilter = 0x0;

TIM_ICInitStructure.TIM_Channel = TIM_Channel_1;

TIM_ICInit(TIM3, &TIM_ICInitStructure);

 

TIM_ICInitStructure.TIM_Channel = TIM_Channel_2;

TIM_ICInit(TIM3, &TIM_ICInitStructure);

 

TIM_ICInitStructure.TIM_Channel = TIM_Channel_3;

TIM_ICInit(TIM3, &TIM_ICInitStructure);

 

 

 

TIM_ICInitStructure.TIM_Channel = TIM_Channel_4;

TIM_ICInit(TIM3, &TIM_ICInitStructure);

 

 

 

/* Enable the CC2 Interrupt Request */

TIM_ITConfig(TIM3,TIM_IT_CC1 |TIM_IT_CC2 |TIM_IT_CC3 |TIM_IT_CC4 , ENABLE);

/* TIM enable counter */

TIM_Cmd(TIM3, ENABLE);

}

 

uint16_t RecvCom[4];

uint16_t RecvCom_old[4]={0,0,0,0};

extern unsigned char Recv1_Flag,Recv2_Flag,Recv3_Flag,Recv0_Flag;

static char pulseState1 = 0,pulseState2 = 0,pulseState3 = 0,pulseState4 = 0;

uint16_t cal(uint32_t u1,uint32_t u2)

{

if(u1>u2)

return u1-u2;

else

return u1+0xffff-u2;

}

void TIM3_IRQHandler(void)

{

 

if (TIM3 ->SR & TIM_IT_CC1 ) 

{

TIM3 ->SR &= (~TIM_IT_CC1 );

if (pulseState1 == 0) 

        {

TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Falling;

RecvCom_old[0] = TIM_GetCapture1(TIM3 );

// TIM_SetCounter(TIM3,0);

}

        else 

        {

TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;

// RecvCom[0] = (TIM_GetCapture1(TIM3 )-RecvCom_old[0]);

RecvCom[0] = cal(TIM_GetCapture1(TIM3 ),RecvCom_old[0]);

Recv0_Flag=1;

}

pulseState1 = !pulseState1;

TIM_ICInitStructure.TIM_Channel = TIM_Channel_1;

TIM_ICInit(TIM3, &TIM_ICInitStructure);

 

}

if (TIM3 ->SR & TIM_IT_CC2 ) {

TIM3 ->SR &= (~TIM_IT_CC2 );

if (pulseState2 == 0) {

TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Falling;

RecvCom_old[1] = TIM_GetCapture2(TIM3 );

 

} else {

TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;

// RecvCom[1] = (TIM_GetCapture2(TIM3 )-RecvCom_old[1]);

RecvCom[1] = cal(TIM_GetCapture2(TIM3 ),RecvCom_old[1]);

Recv1_Flag=1;

}

pulseState2 = !pulseState2;

 

TIM_ICInitStructure.TIM_Channel = TIM_Channel_2;

TIM_ICInit(TIM3, &TIM_ICInitStructure);

 

}

 

if (TIM3 ->SR & TIM_IT_CC3 ) {

TIM3 ->SR &= (~TIM_IT_CC3 );

if (pulseState3 == 0) {

TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Falling;

RecvCom_old[2] = TIM_GetCapture3(TIM3 );

 

} else {

TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;

// RecvCom[2] = (TIM_GetCapture3(TIM3 )-RecvCom_old[2]);

RecvCom[2] = cal(TIM_GetCapture3(TIM3 ),RecvCom_old[2]);

Recv2_Flag=1;

}

pulseState3 = !pulseState3;

 

TIM_ICInitStructure.TIM_Channel = TIM_Channel_3;

TIM_ICInit(TIM3, &TIM_ICInitStructure);

 

}

 

if (TIM3 ->SR & TIM_IT_CC4 ) {

TIM3 ->SR &= (~TIM_IT_CC4 );

if (pulseState4 == 0) {

TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Falling;

RecvCom_old[3] = TIM_GetCapture4(TIM3 );

 

 

} else {

TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;

// RecvCom[3] =( TIM_GetCapture4(TIM3 )-RecvCom_old[3]);

RecvCom[3] =cal( TIM_GetCapture4(TIM3 ),RecvCom_old[3]);

Recv3_Flag=1;

}

pulseState4 = !pulseState4;

 

TIM_ICInitStructure.TIM_Channel = TIM_Channel_4;

TIM_ICInit(TIM3, &TIM_ICInitStructure);

 

}

}

正点原子

帮顶。。。。。

EvanLin

通过STM32的输入捕获定时器，捕获ppm的上升沿和下降沿，计算时间，从而得到解码信息。PPM为Pulse Position Modulation，可译为脉冲位置调制，又称脉位调制.其组成多为头码+脉冲数.PPM以其编码方式简单,使用方便而曾经被广泛的使用在一些无线遥控系统中。有完整的程序更好分析。

gbrgbr123

楼主有没有想到好办法，我之前做直接用延时的，用中断感觉都不太准，如果用PWM的话，每输出一个就得改下频率和占空比才可以