//Fosc=11.0592MHz
// states for and variables IR data processing ;
typedef enum {
    IR_idle,
    IR_waitstart,
    IR_getaddr,
    IR_getaddrinv,
    IR_getdata,
    IR_getdatainv
} _IRstate;
_IRstate IRstate = IR_idle;
unsigned char IRaddr = 0xff;
unsigned char _IRaddr = 0xff;
unsigned char IRdata = 0xff;
unsigned char _IRdata = 0xff;
unsigned char IR_repeat = 0;
unsigned char IR_ready = 0;
unsigned charIR_poweron = 0;
//bit ir_done=0;
// time constants
unsigned int IRtimer = 0; // IR timeout
//cpu初始化
void cpu_init(void)
{
    TMOD = 0X11; // T0 and T1 十六位定时
    TH0 = 0xee; //fosc=11.0592M,timer=5ms
    TL0 = 0x00;
    TR0 = 1; // run timer 0;
    TF0 = 0;
    ET0 = 1; // enable tmr 0 overflow interrupt
    IT0 = 1; // int0 edge sensitive
    EX0 = 1; //enable "int0"
    EA = 1; // global interupt enable
}

//T0中断
void tmrint() interrupt 1
{
    TH0 = 0xee;
    TL0 = 0x00;
    if (IRtimer) { //IR接收超时
        --IRtimer;    //
    }
    else {
        IRstate = IR_idle;
//IR_poweron=0;
    }
}

//Fosc=11.0592MHz
#define msec_12p50x2d00
#define msec_150x3600
#define msec_90x2066
//#define msec_90x1066
#define msec_2p50x900
#define msec_0p90x33d
#define msec_1p680x610
//void IRint() interrupt 0(void)
//When the IR receive pin goes low and interrupt is generated
// IR is collected by starting timer 2 in the first falling edge of the pin
// then on every other falling edge, the timer value is saved and the timer restarted .
// the captured time is then used to get the IR data
// a "start of data" is 13.5Msec,a "1" is 2.25Msec,a "0" is 1.12 msec and a "repeat" is 11.25msec.
// the counter increments at 1.085 Usec
// I allow a fairly large tolerance to time jitter but there are no false triggers seen.
void IRint() interrupt 0
{
    static unsigned char bits;
    unsigned short time;
    switch (IRstate) {
    case IR_idle:
        TL1 = 0;
        TH1 = 0;
        TR1 = 1;
        IRstate = IR_waitstart;
        IRtimer = 26;
        break;
    case IR_waitstart: //P2_4=!P2_4;
        TR1 = 0;
        time = TH1;
        time = (time << 8) + TL1;;
        TL1 = 0;
        TH1 = 0;
        TR1 = 1;
        if ((time > msec_12p5) && (time < msec_15)) { // greater than 12.5Msec & less than 15 msec = start code
            IRaddr = 0;
            _IRaddr = 0;
            IRdata = 0;
            _IRdata = 0;
            bits = 1;
            IRstate = IR_getaddr;
        }
        else if ((time > msec_9) && (time {
        IR_repeat = 2;
        IRstate = IR_idle;
    }
    else {
        // to short, bad data just go to idle
        IRstate = IR_idle;
    }
    break;
case IR_getaddr:// P2_4=!P2_4;
        TR1 = 0;
              time = TH1;
              time = (time << 8) + TL1;;


              TL1 = 0;


              TH1 = 0;


              TR1 = 1;


              if ((time > msec_2p5) || (time


        {


            IRstate = IR_idle;


            break;


        }


    if (time > msec_1p68) // greater than 1.68Msec is a 1


    {


        IRaddr |= bits;


    }


    bits = bits << 1;


           if (!bits)


    {


        IRstate = IR_getaddrinv;


        bits = 1;


    }


    break;


case IR_getaddrinv://P2_4=!P2_4;


        TR1 = 0;


              time = TH1;


              time = (time << 8) + TL1;;


              TL1 = 0;


              TH1 = 0;


              TR1 = 1;


              if ((time > msec_2p5) || (time


        {


            IRstate = IR_idle;


            break;


        }


    if (time > msec_1p68) // greater than 1.68Msec is a 1


    {


        _IRaddr |= bits;


    }


    bits = bits << 1;


           if (!bits)


    {


        IRstate = IR_getdata;;


        bits = 1;


    }


    break;


case IR_getdata:


        TR1 = 0;


              time = TH1;


              time = (time << 8) + TL1;;


              TL1 = 0;


              TH1 = 0;


              TR1 = 1;


              if ((time > msec_2p5) || (time


        {


            IRstate = IR_idle;


            break;


        }


    if (time > msec_1p68) // greater than 1.68Msec is a 1


    {


        IRdata |= bits;


    }


    bits = bits << 1;


           if (!bits)


    {


        IRstate = IR_getdatainv;


        bits = 1;


    }


    break;


case IR_getdatainv:


        TR1 = 0;


              time = TH1;


              time = (time << 8) + TL1;;


              TL1 = 0;


              TH1 = 0;


              TR1 = 1;


              if ((time > msec_2p5) || (time


        {


            IRstate = IR_idle;


            break;


        }


    if (time > msec_1p68) // greater than 1.68Msec is a 1


    {


        _IRdata |= bits;


    }


    bits = bits << 1;


           if (!bits)// we have it all , now we make sure it is a NEC code from the CHS IR transmitter


    {
        // make sure address,~address are correct , data ,~data are correct and address is 0.


        IR_ready = ((IRaddr ^ _IRaddr) == 0xff) && ((IRdata ^ _IRdata) == 0xff) && (IRaddr == 0);


            if (IR_ready)


            {


                IRstate = IR_idle;


            }


        }


        break;


    default:


            IRstate = IR_idle;


                      break;


        }


}





void main(void)


{


    cpu_init();


    while (1)


    {


        if (IR_ready)


        {


            IR_ready = 0;


            switch (IRdata)


            {


            case 0x45://1


//your code


                break;


            case 0x44://3


//your code


                break;


            case 0x43://4


//your code


                break;


            case 0x08://prev


//your code


                break;


            case 0x5a://next


//your code


                break;


            default:


                break;


            }


        }


    }


}