slime@2: /*
slime@2:  * Project Frontplatte
slime@2:  *
slime@2:  * rc5.c  -  decode rc5 signals
slime@2:  *
slime@2:  * This file is released under the GNU General Public License. Refer
slime@2:  * to the COPYING file distributed with this package.
slime@2:  *
slime@2:  * (c) 2007 Carsten Presser cpresser AT fsing.uni-sb.de
slime@2:  */
slime@2: 
slime@2: #include <p18cxxx.h>
slime@2: #include "rc5.h"
slime@2: #include "io_cfg.h"
slime@2: #include "delay.h"
slime@2: #include "user.h"
slime@2: 
slime@2: #include <timers.h>
slime@2: 
slime@2: /** V A R I A B L E S **********************************************/
slime@2: unsigned char rc5_status;
slime@2: unsigned int  rc5_receive_buffer;
slime@2: unsigned char gg_ir;
slime@2: unsigned char gg_ir_address;
slime@2: 
slime@2: /** C O D E ********************************************************/
slime@2: void rc5_init(void)
slime@2: {
slime@2: 	OpenTimer0(TIMER_INT_ON & T0_8BIT & T0_SOURCE_INT & T0_PS_1_256);
slime@2: 	// SOLLTE SEIN: ein Timer Takt = 51,2 E-6 sec. (mit prescaler 256)
slime@2: 	// ist aber 25,6usec [woher kommt das 1/2??]
slime@2: 
slime@2: /*	kurze pulsdauer: 		444us	bis		1333us		mitte:	889us
slime@2: 	entspricht in timer0:	17,3			52,0				34,7
slime@2: 
slime@2: 	lange pulsdauer:		1334us	bis		2222us				1778us
slime@2: 	in timer0:				52,1			87					69,5*/
slime@2: 
slime@2: 	INTCONbits.TMR0IF	= 0;	// clear flag
slime@2: 	INTCON2bits.TMR0IP	= 1;	// make TMR0 a high-priority-interrupt
slime@2: 
slime@2: 	rc5_receive_buffer	= 0x0000;
slime@2: 	gg_ir_address		= 0xFF;
slime@2: 	gg_ir 				= 0xFF;
slime@2: 	rc5_status			= RC5_UNDEF;
slime@2: }
slime@2: 
slime@2: void rc5_decode(void)
slime@2: {
slime@2: 	unsigned char tmr0;
slime@2: 	unsigned char pulse = 0xFF;
slime@2: 
slime@2: /* G E T   P U L S E W I D T H   &  T Y P E */
slime@2: 	tmr0 = (unsigned char)(ReadTimer0());
slime@2: 	// decide if this is long or short...
slime@2: 	if ((tmr0 > 20) && (tmr0 < 49)) {pulse = RC5_SPACE_SHORT;}
slime@2: 	if ((tmr0 > 55) && (tmr0 < 82)) {pulse = RC5_SPACE_LONG;}
slime@2: 
slime@2: 	// if RB0 = 1 -> this is a space, not a pulse -> add one
slime@2: 	pulse += PIN_IR;
slime@2: 
slime@2: /* S T A T U S    M A C H I N E */
slime@2: 	switch (rc5_status)
slime@2: 	{
slime@2: 		case RC5_MID1:
slime@2: 			if (pulse == RC5_PULSE_SHORT)
slime@2: 			{
slime@2: 				rc5_status = RC5_START1;
slime@2: 			}
slime@2: 			else if (pulse == RC5_PULSE_LONG)
slime@2: 			{
slime@2: 				rc5_status = RC5_MID0;
slime@2: 				rc5_receive_buffer = rc5_receive_buffer << 1;		// emit zero
slime@2: 			}
slime@2: 			else
slime@2: 				rc5_scrap();
slime@2: 			break;
slime@2: 
slime@2: 		case RC5_MID0:
slime@2: 			if (pulse == RC5_SPACE_SHORT)
slime@2: 			{
slime@2: 				rc5_status = RC5_START0;
slime@2: 			}
slime@2: 			else if (pulse == RC5_SPACE_LONG)
slime@2: 			{
slime@2: 				rc5_status = RC5_MID1;
slime@2: 				rc5_receive_buffer = rc5_receive_buffer << 1;
slime@2: 				rc5_receive_buffer |= 0x01;							// emit one
slime@2: 			}
slime@2: 			else
slime@2: 				rc5_scrap();
slime@2: 			break;
slime@2: 
slime@2: 		case RC5_START1:
slime@2: 			if (pulse == RC5_SPACE_SHORT) 
slime@2: 			{
slime@2: 				rc5_status = RC5_MID1;
slime@2: 				rc5_receive_buffer = rc5_receive_buffer << 1;
slime@2: 				rc5_receive_buffer |= 0x01;							// emit one
slime@2: 			}
slime@2: 			else
slime@2: 				rc5_scrap();
slime@2: 			break;
slime@2: 		
slime@2: 		case RC5_START0:
slime@2: 			if (pulse == RC5_PULSE_SHORT)
slime@2: 			{
slime@2: 				rc5_status = RC5_MID0;
slime@2: 				rc5_receive_buffer = rc5_receive_buffer << 1;		// emit zero
slime@2: 			}
slime@2: 			else
slime@2: 				rc5_scrap();
slime@2: 			break;
slime@2: 
slime@2: 		case RC5_DONE:
slime@2: 		case RC5_UNDEF:
slime@2: 		default:
slime@2: 			rc5_scrap();
slime@2: 			break;
slime@2: 	}
slime@2: 	
slime@2: 	// i recieved 13 + startbit bits...
slime@2: 	if (rc5_receive_buffer & 0x6000) 
slime@2: 	{
slime@2: 		rc5_status = RC5_DONE;
slime@2: 		gg_ir 			= (unsigned char)(rc5_receive_buffer & 0x3F);			// lower 6 bits -> command
slime@2: 		gg_ir_address	= (unsigned char)((rc5_receive_buffer & 0x032) >> 6);	// upper 6 bits -> address + toogle
slime@2: 
slime@2: 		gg_ioflags		|= FLAG_IR;
slime@2: 	}
slime@2: 
slime@2: 	// reset timer and wait for next pulse....
slime@2: 	WriteTimer0(0x00);
slime@2: }
slime@2: 
slime@2: 
slime@2: void rc5_scrap(void) 
slime@2: {
slime@2: 	// enter start-state and emit one
slime@2: 	rc5_status = RC5_MID1;
slime@2: 	rc5_receive_buffer = 0x0001;
slime@2: }