/*

 * Project Frontplatte

 *

 * rc5.c  -  decode rc5 signals

 *

 * This file is released under the GNU General Public License. Refer

 * to the COPYING file distributed with this package.

 *

 * (c) 2007 Carsten Presser cpresser AT fsing.uni-sb.de

 */

#include <p18cxxx.h>

#include "rc5.h"

#include "io_cfg.h"

#include "delay.h"

#include "user.h"

#include <timers.h>

/** V A R I A B L E S **********************************************/

unsigned char rc5_status;

unsigned int  rc5_receive_buffer;

unsigned char gg_ir;

unsigned char gg_ir_address;

/** C O D E ********************************************************/

void rc5_init(void)

{

	OpenTimer0(TIMER_INT_ON & T0_8BIT & T0_SOURCE_INT & T0_PS_1_256);

	// SOLLTE SEIN: ein Timer Takt = 51,2 E-6 sec. (mit prescaler 256)

	// ist aber 25,6usec [woher kommt das 1/2??]

/*	kurze pulsdauer: 		444us	bis		1333us		mitte:	889us

	entspricht in timer0:	17,3			52,0				34,7

	lange pulsdauer:		1334us	bis		2222us				1778us

	in timer0:				52,1			87					69,5*/

	INTCONbits.TMR0IF	= 0;	// clear flag

	INTCON2bits.TMR0IP	= 1;	// make TMR0 a high-priority-interrupt

	rc5_receive_buffer	= 0x0000;

	gg_ir_address		= 0xFF;

	gg_ir 				= 0xFF;

	rc5_status			= RC5_UNDEF;

}

void rc5_decode(void)

{

	unsigned char tmr0;

	unsigned char pulse = 0xFF;

/* G E T   P U L S E W I D T H   &  T Y P E */

	tmr0 = (unsigned char)(ReadTimer0());

	// decide if this is long or short...

	if ((tmr0 > 20) && (tmr0 < 49)) {pulse = RC5_SPACE_SHORT;}

	if ((tmr0 > 55) && (tmr0 < 82)) {pulse = RC5_SPACE_LONG;}

	// if RB0 = 1 -> this is a space, not a pulse -> add one

	pulse += PIN_IR;

/* S T A T U S    M A C H I N E */

	switch (rc5_status)

	{

		case RC5_MID1:

			if (pulse == RC5_PULSE_SHORT)

			{

				rc5_status = RC5_START1;

			}

			else if (pulse == RC5_PULSE_LONG)

			{

				rc5_status = RC5_MID0;

				rc5_receive_buffer = rc5_receive_buffer << 1;		// emit zero

			}

			else

				rc5_scrap();

			break;

		case RC5_MID0:

			if (pulse == RC5_SPACE_SHORT)

			{

				rc5_status = RC5_START0;

			}

			else if (pulse == RC5_SPACE_LONG)

			{

				rc5_status = RC5_MID1;

				rc5_receive_buffer = rc5_receive_buffer << 1;

				rc5_receive_buffer |= 0x01;							// emit one

			}

			else

				rc5_scrap();

			break;

		case RC5_START1:

			if (pulse == RC5_SPACE_SHORT) 

			{

				rc5_status = RC5_MID1;

				rc5_receive_buffer = rc5_receive_buffer << 1;

				rc5_receive_buffer |= 0x01;							// emit one

			}

			else

				rc5_scrap();

			break;

		case RC5_START0:

			if (pulse == RC5_PULSE_SHORT)

			{

				rc5_status = RC5_MID0;

				rc5_receive_buffer = rc5_receive_buffer << 1;		// emit zero

			}

			else

				rc5_scrap();

			break;

		case RC5_DONE:

		case RC5_UNDEF:

		default:

			rc5_scrap();

			break;

	}

	// i recieved 13 + startbit bits...

	if (rc5_receive_buffer & 0x6000) 

	{

		rc5_status = RC5_DONE;

		gg_ir 			= (unsigned char)(rc5_receive_buffer & 0x3F);			// lower 6 bits -> command

		gg_ir_address	= (unsigned char)((rc5_receive_buffer & 0x032) >> 6);	// upper 6 bits -> address + toogle

		gg_ioflags		|= FLAG_IR;

	}

	// reset timer and wait for next pulse....

	WriteTimer0(0x00);

}

void rc5_scrap(void) 

{

	// enter start-state and emit one

	rc5_status = RC5_MID1;

	rc5_receive_buffer = 0x0001;

}