/* -*- mode: c -*- */

////////////////////////////////////////////////////////////////////////////////////////////////////
// IR REMOTE CONTROL DECODER FOR XBOX (DVDKit)
// 2007 Javier Valcarce García, javier.valcarce@gmail.com
// $Id$
////////////////////////////////////////////////////////////////////////////////////////////////////
#include <avr/io.h>
#include <avr/interrupt.h>


// This is the INT0 Pin of the ATMega8
#define PIN_IRRX 2

// Xbox IR remote control codes
#define       IRCODE_DISPLAY       0x52AAD5
#define       IRCODE_REVERSE       0x51DAE2
#define       IRCODE_PLAY          0x515AEA
#define       IRCODE_FORWARD       0x51CAE3
#define       IRCODE_SKIPSUB       0x522ADD
#define       IRCODE_STOP          0x51FAE0
#define       IRCODE_PAUSE         0x519AE6
#define       IRCODE_SKIPADD       0x520ADF
#define       IRCODE_TITLE         0x51AAE5
#define       IRCODE_INFO          0x53CAC3
#define       IRCODE_MENU          0x508AF7
#define       IRCODE_BACK          0x527AD8
#define       IRCODE_UP            0x559AA6
#define       IRCODE_DOWN          0x558AA7
#define       IRCODE_LEFT          0x556AA9
#define       IRCODE_RIGHT         0x557AA8
#define       IRCODE_SELECT        0x5F4A0B
#define       IRCODE_1             0x531ACE
#define       IRCODE_2             0x532ACD
#define       IRCODE_3             0x533ACC
#define       IRCODE_4             0x534ACB
#define       IRCODE_5             0x535ACA
#define       IRCODE_6             0x536AC9
#define       IRCODE_7             0x537AC8
#define       IRCODE_8             0x538AC7
#define       IRCODE_9             0x539AC6
#define       IRCODE_0             0x530ACF
////////////////////////////////////////////////////////////////////////////////////////////////////

volatile unsigned int   usec;
volatile int            ir_bit;
volatile unsigned long  ir_tmp;
volatile unsigned long  ir_cmd;
volatile boolean        ir_cmd_new;

// Decoder state (variable "ir_bit") -1, 0, 1, 2, 3... 24 and (25)

#define WAIT      -1    // Waiting for an IR signal
#define HEAD      0     // Receiving AGC pulse 
//...

#define PERR      250   // Maximun absolute error permited inÇ              vcxxz ZXC

#define TIME_HEAD 4500  // AGC pulse lenght (in us)
#define TIME_BIT0 1500  // Bit 0 lenght (in us)
#define TIME_BIT1 2500  // Bit 1 lenght (in us)


// Aruino runs at 16 Mhz, 
// Raise interrupt every 1 / ((16000000 / 1) / 256) = 1 / 62500 = 16us
////////////////////////////////////////////////////////////////////////////////////////////////////
ISR(TIMER2_OVF_vect) 
{
      usec += 16;
      if (usec == 6400)  // 6400 % 16 == 0
      {
	    // Time over! Reset receiver's state machine 
	    usec   = 0;
	    ir_bit = WAIT;
      } 
};


////////////////////////////////////////////////////////////////////////////////////////////////////
#define VALID_TIME(v, a, b) ( ((v) > (a)-PERR) && ((v) < (b)+PERR) )

// INT0, arduino pin2
ISR(INT0_vect) 
{
      switch (ir_bit) 
      {
      case WAIT:        
	    // Waiting for an incoming signal
	    if (!ir_cmd_new) ir_bit++; 
	    break;
          
      case HEAD:
            // Initial AGC pulse
	    if ( VALID_TIME(usec, TIME_HEAD) ) 
	    {
		  ir_tmp = 0;
		  ir_bit++;
	    }
	    else 
	    {
		  ir_bit = WAIT;		
	    }
	    break;
    
      default:
	    // Data bits 01, 02, 03, ... 24
	    if ( VALID_TIME(usec, TIME_BIT0) ) 
	    {
		  ir_tmp = ir_tmp << 1;
		  ir_bit++;
	    }  
	    else if ( VALID_TIME(usec, TIME_BIT1) ) 
	    {
		  ir_tmp = (ir_tmp << 1) | 0x00000001;
		  ir_bit++;
	    }
	    else 
	    {
		  ir_bit = WAIT;
	    }
        
	    if (ir_bit == 25)  
	    {
		  // Bit "25" means END OF TRANSMISION, new IR data is available
		  ir_cmd     = ir_tmp;
		  ir_cmd_new = true;
	    }
        
	    break;
      }

      usec = 0;
}



////////////////////////////////////////////////////////////////////////////////////////////////////
void setup() 
{ 
      
      usec = 0;
      ir_bit  = WAIT;
      ir_cmd_new = false;

      pinMode(PIN_IRRX, INPUT); 
    
      // Timer Setup, valid only for ATmega8 
      // Normal mode
      TCCR2 &= ~(1 << WGM21);
      TCCR2 &= ~(1 << WGM20);
        
      // No Timer Prescaler
      TCCR2 |=  (1 << CS20); 
      TCCR2 &= ~(1 << CS22);
      TCCR2 &= ~(1 << CS21);

      // Use internal clock
      ASSR  &= ~(1 << AS2);
    
      // TMR2 Overflow Interrupt
      TIMSK |=  (1 << TOIE2);  
      TIMSK &= ~(1 << OCIE2);	       

      // INT0 interrupt
      GICR  |= (1 << INT0);
      MCUCR |= (1 << ISC00);  // positive edge
      MCUCR |= (1 << ISC01);  // negative edge

      sei();

      Serial.begin(9600); 
  
      // prints title with ending line break 
      Serial.println("");  
      Serial.println("Xbox IR remote control"); 
      Serial.println("Waiting...");       
      // wait for the long strings to be sent to serial port      
      delay(100);
} 

////////////////////////////////////////////////////////////////////////////////////////////////////
void loop() 
{ 
      if (ir_cmd_new)
      {
	    Serial.print("code - ");
	    Serial.println(ir_cmd, HEX);
	    ir_cmd_new = false;

            delay(40);
      }
}
////////////////////////////////////////////////////////////////////////////////////////////////////