ir.c

C code for using 8051 to control philiphs I2C FM tuner (use sdcc compiler)

#include <at89x52.h>
#include "ir.h"
#include "i2c.h"
#include "tuner.h"

static unsigned char	impulse = 0;
static unsigned char	eximpulse = 0;
static unsigned char	IR_flag = 0;
static unsigned short	impulseCounter = 0;
static unsigned short	spaceCounter = 0;
static unsigned char	preDataCounter = 0;
static unsigned char	bitCounter = 0;
static unsigned short	keycode = 0;

static unsigned char tuner_data[5] = {0x00};
static unsigned char channel = 5;

/* IR Initial */
void IR_Initial(void) 
{
	IR_DETECT_PIN = 1;  /* Set IR Detect Pin as input Pin */
	TCON	=	0x00;
	TMOD	=	0x01;
	IP		=	0x01;
	IE		=	0x83;
	TL0 	= 	_TL0_;
	TH0 	= 	_TH0_;
	TR0 	= 	1;		/* IR Timer Run */
}

/* IR Decoder Algorithm */
void IR_Timer(void) interrupt 1
{
    /* Reload the timer counts */	
    TL0 = _TL0_;
    TH0 = _TH0_;
 
    if ( IR_DETECT_PIN == 1) 
       impulse=0; 
    else 
       impulse=1;
 
    if ((eximpulse==0) && (impulse==1)) // Rising Edge
    {
        impulseCounter=0;
 
        if ((spaceCounter>1)&&(IR_flag==1)&&(spaceCounter<24)) 
        {
           preDataCounter++;
 
           if ((spaceCounter<10) && (preDataCounter>16))
           {
             keycode <<= 1;
             bitCounter++;             
           }    
           if ((spaceCounter>10) && (preDataCounter>16))
           {
             keycode <<= 1;         
             keycode |= 1; 
             bitCounter++; 
           }     
 
        }          
    }       
 
	if((impulse==1)&&(impulseCounter<200))
		impulseCounter++;
 
 
	if((eximpulse==1)&&(impulse==0)) //falling edge
	{
    	spaceCounter=0;
 
    	if(impulseCounter>30)
    		IR_flag=1;
	}
 
	if((impulse==0)&&(IR_flag==1)&&(impulseCounter<150))
	//counting negative pulses
		spaceCounter++;
 
	 if (bitCounter == 16)
 	{
		if (keycode == 0x6897) // power
		{
			channel = 9; // max channel
		}
		else if (keycode == 0xA05F) // CH+
		{
			if (channel == 11) // max channel
				channel = 5;   // min channel
			else
				channel += 2;
		}
		else if (keycode == 0x40BF) // CH-
		{
 			if (channel == 5) // min channel
				channel = 11; // max channel
			else
				channel -= 2;
        }
#if 0
		else if (keycode == 0x50AF) // Vol-
		{
     	}
		else if (keycode == 0x7887) // Vol+
		{
     	}
#endif
	switch (channel) {
		/*
			NTSC USA, fVIF = 45.75MHz, fss = 62.5KHz
	         	Test Cable Channel 7, fRF = 175.25MHz, TV Mid Band
		*/
		case 7:
			tuner_data[0] = 0x0D; // DB1
			tuner_data[1] = 0xD0; // DB2
			tuner_data[2] = 0xCE; // CB
			tuner_data[3] = 0x02; // BB
			tuner_data[4] = 0x20; // AB
		break;
        
       	/*
			Test Cable Channel 11, fRF = 199.25MHz, TV Mid Band
		*/
		case 11:
			tuner_data[0] = 0x0F; // DB1
			tuner_data[1] = 0x50; // DB2
			tuner_data[2] = 0xCE; // CB
			tuner_data[3] = 0x02; // BB
			tuner_data[4] = 0x20; // AB
		break;
 
		/*
			Test Cable Channel 5 , fRF = 77.25MHz, TV Low Band
			(77.25 + 45.75) *  1000 / 62.5
		*/
		case 5:
			tuner_data[0] = 0x07; // DB1
			tuner_data[1] = 0xB0; // DB2
			tuner_data[2] = 0xCE; // CB
			tuner_data[3] = 0x01; // BB
			tuner_data[4] = 0x20; // AB
		break;
	
		/*
			Test Cable Channel 9 , fRF = 187.25MHz, TV Mid Band
			(187.25 + 45.75) *  1000 / 62.5
		*/
		case 9:
			tuner_data[0] = 0x0E; // DB1
			tuner_data[1] = 0x90; // DB2
			tuner_data[2] = 0xCE; // CB
			tuner_data[3] = 0x02; // BB
			tuner_data[4] = 0x20; // AB
		break;
 
		}
 
		/* Write Data to Tuner */
		tuner_write(tuner_data);
		I2C_NOP();
 
		/* Reset counters */
		preDataCounter=0;
		IR_flag=0;
		spaceCounter=0;
		impulseCounter=0;
		keycode = 0;
		bitCounter=0;
 	}
	 if (spaceCounter > 300)
 	{
 		preDataCounter=0;
		IR_flag=0;
		spaceCounter=0;
		impulseCounter=0;
		keycode = 0;
		bitCounter=0;     
 	}
 
	eximpulse=impulse;
 
}