单片机红外线接收算法

红外线遥控目前在市面上用得比较的广泛，如遥控电视，遥控灯具，遥控玩具等等。

这里主要介绍一下红外遥控接收代码的编写，先看红外接收代码：

void user_gpio_init(void)
{
  /*!< Output push-pull, low level, 10MHz */
  GPIO_Init(GPIOC, GPIO_PIN_LNIB, GPIO_MODE_OUT_PP_LOW_SLOW);//FI 0..3
  GPIO_Init(GPIOC, GPIO_PIN_4, GPIO_MODE_OUT_PP_LOW_SLOW);//BI
  /*!< Input pull-up, external interrupt */
  GPIO_Init(GPIOC, GPIO_PIN_7, GPIO_MODE_IN_PU_IT);   //Data
  /*@brief  Set the external interrupt sensitivity of the selected port.*/
  /*!< Interrupt on Falling edge only */
  EXTI_SetExtIntSensitivity(EXTI_PORT_GPIOC, EXTI_SENSITIVITY_FALL_ONLY);
}
//interrupt routine
void portC_isr(void)
{
  static u8 one_byte;
  static u8 index;
  static u8 bits_of_byte;
  switch(IR_State)
  {
  case IDL:
    {
      time_125us=0;
      IR_State++;
      break;
    }
  case START:
    {
      if(time_125us>104)//ok , ready to receive data
      {
        time_125us=0;
        one_byte = 0;
        index=0;
        bits_of_byte = 0;
        IR_State++;
      }
      else IR_State--;
      break;
    }
  case DATA:
    {
      if((time_125us<14)&&(time_125us>6))//0
      {
        one_byte <<=1;
        bits_of_byte++;
      }
      else if((time_125us>14)&&(time_125us<23))//1
      {
        one_byte<<=1;
        one_byte+=1;
        bits_of_byte++;
      }
      else
      {
        IR_State = IDL;
      }
      time_125us=0;
      if(bits_of_byte >= 8)                     // got one byte ready
      {
        g_u8arr_buf[index++]=one_byte;
        time_release_125us=0;
        if(index>=4)
        {
          //__disable_interrupt();
          if ((g_u8arr_buf[3]==0x13)&&(g_u8arr_buf[2]==0xEC)&&(g_u8arr_buf[1]==0xff)&&g_u8arr_buf[0]==0x00)//0x00FFEC13
          {
            if(g_motor_busy!=0x00)
            {
              MotorStop;
              g_motor_busy=0;
            }
          }
          else if ((g_u8arr_buf[3]==0x53)&&(g_u8arr_buf[2]==0xAC)&&(g_u8arr_buf[1]==0xff)&&g_u8arr_buf[0]==0x00)//0x00FFAC53
          {
            //time_release_125us=0;
            if(g_motor_busy!=0x5a)
            {
              MotorForward;
              g_motor_busy=0x5a;
            }
          }
          else if ((g_u8arr_buf[3]==0x33)&&(g_u8arr_buf[2]==0xCC)&&(g_u8arr_buf[1]==0xff)&&g_u8arr_buf[0]==0x00)//0x00FFCC33
          {
            //time_release_125us=0;
            if(g_motor_busy!=0x3c)
            {
              MotorBackward;
              g_motor_busy=0x3c;
            }
          }
          else
          {
            if(g_motor_busy!=0x00)
            {
              MotorStop;
              g_motor_busy=0;
            }
          }
          IR_State = IDL;
          //__enable_interrupt();
        }
        bits_of_byte=0;
        one_byte=0;
      }
      break;
    }
  default:
    {
      IR_State = IDL;
      break;
    }
  }
}

红外编码常用格式为：报头为13.5ms信号，之后才开始传送数据。数据的编码：1ms左右代表0或者1,   2ms左右代表1或者0。这个主要看自己的定义了。

这个算法的重点是调好定时器的精度，以及红外线连续读取的灵敏度。