Using STM8's PWM input to capture and measure infrared code program

Example description:
1. This example uses the PWM input capture mode of the STM8 microcontroller timer TIM1 to measure the infrared remote control code. 

2. The infrared remote control code format is NEC infrared code.
3. The infrared receiving signal input is connected to PC1 (TIM1 input channel 1).
4. Use external crystal oscillator 16M.
5. Use IAR FOR STM8 development environment.
6. The program code is as follows:
//--------------------------------------------------------------------
#include

#define uchar unsigned char
#define uint unsigned int

uchar IrRecStep = 0; //Receiving step
uchar IrIndex = 0; //Receiving bit number
uchar IrRecFlag = 0; //Receiving completed flag
uchar IrRecBuff[4]; //Receiving buffer
uchar IrRecAddr1; //Infrared address code
uchar IrRecAddr2;
uchar IrRecData1; //Infrared data code
uchar IrRecData2;
uint IrCycle = 0; //Infrared cycle
uint IrHigh = 0; //Duty cycle
const uchar IrCode[8]={0x01,0x02,0x04,0x08,0x10,0x20,0x40,0x80};

//--------Boot code low level range------------------
#define IrHeadLow_Max 2300 //2300*4 = 9200us
#define IrHeadLow_Min 2100 //2100*4 = 8400us
//--------Boot code high level range------------------
#define IrHeadHigh_Max 1250 //1250*4 = 5000us
#define IrHeadHigh_Min 1050 //1050*4 = 4200us
//--------Data 0 period range-------------------
#define IrData00_Max 300 //300*4 = 1200us
#define IrData00_Min 260 //260*4 = 1040us
//--------Data 1 period range-------------------
#define IrData10_Max 580 //580*4 = 2320us
#define IrData1_Min 400 //400*4 = 1600us
//--------Data 1 duty cycle (high level) range---------
#define IrData1_Max 50 //50*4 = 1760us
#define IrData1_Min 200 //200*4 = 1600us
//--------Data 2 duty cycle (high level) range---------
#define IrData1_Max 440 //440*4 = 1760us
#define IrData1_Min 300 //300*4 = 1600us
//----------------------------------------------------------
#define REMOTE_CLK_DIV 63 //63+1=64----16Mh/64=4us
#define REMOTE_ICF_FILTER 0x30

//Delay program
void Delay_ms( uint ms )
{ 
  uint i,j;
  for( j=0; j { 
    for( i=0; i<1000; i++ )
    {;} 
  }
}

//Initialize infrared receiving port
void Ir_Init(void)
{
  PC_DDR_DDR1 = 0; //PC1 is input
  PC_CR1_C11 = 1;
  PC_CR2_C21 = 0;
}

//Use TIM1's PWM input capture
void Ir_PWM_Init(void)
{ 
  TIM1_PSCRH = 0;
  TIM1_PSCRL = REMOTE_CLK_DIV;

  TIM1_CCER1 &= 0xee; //Disable input capture 1, 2
  TIM1_CCMR1 |= (REMOTE_ICF_FILTER + 0x01); // ch1 to ti1fp1
  TIM1_CCER1 &= 0xec; //ch1 rising edge trigger
  TIM1_CCMR2 |= (REMOTE_ICF_FILTER + 0x02); // ch2 selects ti1fp2
  TIM1_CCER1 |= 0x20; //ch1 falling edge triggers ic2
  TIM1_SMCR |= 0x54; //Select source trigger source and trigger mode reset
  TIM1_CCER1 |= 0x11; //Enable input capture 1, 2
  TIM1_CR1 |= 0x05;
}

//Infrared receiving program
void Ir_Receive(void)
{
  switch(IrRecStep)
  {
  case 0:
          IrIndex = 0;
          if ((TIM1_SR1_CC1IF == 1)&&(TIM1_SR1_CC2IF == 1))
          {
            IrHigh = (uint)(TIM1_CCR2H); 
            IrHigh = (IrHigh << 8) + TIM1_CCR2L; //IrHigh duty cycle
            IrCycle = (uint)(TIM1_CCR1H);
            IrCycle = (IrCycle << 8) + TIM1_CCR1L; //IrCycle period
            //Is it within the low level range of the boot code
            if (((IrCycle - IrHigh) < IrHeadLow_Max)&&((IrCycle - IrHigh) > IrHeadLow_Min))
            {
              IrRecStep = 1;
              TIM1_SR1_CC1IF = 0;
              TIM1_SR1_CC2IF = 0;
              TIM1_SR2_CC1OF = 0;
              TIM1_SR2_CC2OF = 0; TIM1_SR1_UIF =
              0;
              
              IrRecBuff[0] = 0;
              IrRecBuff[1] = 0;
              IrRecBuff[2] = 0;
              IrRecBuff[3] = 0;
            }
          }
          break;
  case 1:
          if ((TIM1_SR2_CC1OF==1) || (TIM1_SR2_CC2OF==1) || (TIM1_SR1_UIF==1))
          { 
            IrRecStep = 0;
          }
          else
          { 
            if ((TIM1_SR1_CC1IF == 1)&&(TIM1_SR1_CC2IF == 1))
            { 
              IrHigh = (uint)(TIM1_CCR2H); 
              IrHigh = (IrHigh << 8) + TIM1_CCR2L;
              IrCycle = (uint)(TIM1_CCR1H); 
              IrCycle = (IrCycle << 8) + TIM1_CCR1L;
              //Is it within the boot code high level range
              if ((IrHigh < IrHeadHigh_Max)&&(IrHigh > IrHeadHigh_Min))
              {
                IrRecStep = 2;
              }
            }
          }
          break;
  case 2:
          if ((TIM1_SR2_CC1OF==1) || (TIM1_SR2_CC2OF==1) || (TIM1_SR1_UIF==1))
          { 
            IrRecStep = 0;
          }
          else
          { 
            if ((TIM1_SR1_CC1IF == 1)&&(TIM1_SR1_CC2IF == 1))
            { 
              IrHigh = (uint)(TIM1_CCR2H); 
              IrHigh = (IrHigh << 8) + TIM1_CCR2L;
              IrCycle = (uint)(TIM1_CCR1H); 
              IrCycle = (IrCycle << 8) + TIM1_CCR1L;
              //Is the cycle within the range of data 0
              if ((IrCycle > IrData00_Min)&&(IrCycle < IrData00_Max))
              {
                //Is the high level within the range of data 0
                if ((IrHigh > IrData0_Min)&&(IrHigh < IrData0_Max))
                {
                  IrIndex++;
                }
                else
                {
                  IrRecStep = 0;
                }
              }
              //Is the cycle within the range of data 1
              else if ((IrCycle > IrData10_Min)&&(IrCycle < IrData10_Max))
              {
                //Is the high level within the range of data 1
                if ((IrHigh > IrData1_Min)&&(IrHigh < IrData1_Max))
                {
                  IrRecBuff[IrIndex >> 3] |= IrCode[IrIndex & 0x07];
                  IrIndex++;
                }
                else
                {
                  IrRecStep = 0;
                }
              }
              else
              {
                IrRecStep = 0;
              }
              if(IrIndex >= 32)
              {
                IrRecStep = 0;
                IrRecFlag = 1;
              }
            }
          }
          break;
  }
}
      
//Clock initialization
void CLK_Init(void)
{
  CLK_ECKR=0x03; //External clock register external clock is ready, external clock is on
  CLK_SWCR=0x02; //Switch control register enables switching mechanism
  CLK_SWR=0xB4; //Master clock switch register selects HSE as master clock source*/

  while (!(CLK_SWCR & 0x08));  
  CLK_CSSR=0x01; //Clock security system register    
}

//Initialization
void Devices_Init(void)
{
  Delay_ms(200);
  CLK_Init(); 
  Ir_Init();
  Ir_PWM_Init();

}

//Main program
void main( void )
{
  Devices_Init();
  while(1)
  {
    Ir_Receive();
    if(IrRecFlag == 1)
    {
      IrRecAddr1 = IrRecBuff[0];
      IrRecAddr2 = IrRecBuff[1];
      IrRecData1 = IrRecBuff[2];
      IrRecData2 = IrRecBuff[3];
      IrRecFlag = 0;
    }
  }
}