Difference between revisions of "Avr rc5 remote control"

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I'm not going to provide you with my own version of how it works.<br>
 
I'm not going to provide you with my own version of how it works.<br>
 
I suggest you read this: http://www.sbprojects.com/knowledge/ir/rc5.htm<br>
 
I suggest you read this: http://www.sbprojects.com/knowledge/ir/rc5.htm<br>
That link also has a list of the command and adress codes that you'll need.
+
That link also has a list of the command and address codes that you'll need.
 
<br><br><br><br><br><br><br><br><br>
 
<br><br><br><br><br><br><br><br><br>
 
   
 
   
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data.raw = 0;
 
data.raw = 0;
  
// triggers on faling edge of start bit 1.
+
// triggers on falling edge of start bit 1.
 
_delay_ms(0.2);
 
_delay_ms(0.2);
  
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{
 
{
 
init_int0();
 
init_int0();
sei(); // Enable interrupts
+
sei(); // Enable interrupts
  
 
while(1) {
 
while(1) {

Revision as of 07:14, 2 August 2009


Introduction

The test setup Just a quick snapshot of the test setup. An STK500 cruedly interfaced to a TSOP1736 solderen on a recycled prototype pcb.

Interfacing a standard Philips RC5 protocol remote control to an Atmel AVR should be easy. It shouldn't have to take neither much hardware nor code to do so. I've found that there is an official application note from Atmel describing how to do this. Atmels example is done in assembler and is fault tolerant, but it's difficult to understand. By doing it in C it becomes very simple and understandable.










The RC5 protocol

The Remote Control A worn Philips remote control used for testing.

I'm not going to provide you with my own version of how it works.
I suggest you read this: http://www.sbprojects.com/knowledge/ir/rc5.htm
That link also has a list of the command and address codes that you'll need.








The Code

The stripped down C code:

#include <avr/interrupt.h>
#include <avr/io.h>
#include <util/delay.h>

typedef union { 
	uint16_t raw;
	struct {
		unsigned cmd    : 6;	// LSB
		unsigned addr   : 5;
		unsigned toggle : 1;
		unsigned start  : 2;
		unsigned        : 2;	// MSB
	};
} rc5data;

static volatile int flag = 0;
static volatile rc5data data;

void init_int0()
{
	// Interrupt on INT0 pin going low
	MCUCR = (1 << ISC01);

	// Turn on INT0!
	GICR |= (1 << INT0);
}

SIGNAL (INT0_vect)
{	
	int pos = 0;

	if (!flag) {
		data.raw = 0;

		// triggers on falling edge of start bit 1.
		_delay_ms(0.2);

		while (pos < 14) {
			data.raw = (data.raw << 1) | ((~PIND & 0x04) >> 2);
			_delay_ms(1.8);
			pos++;
		}

		flag = 1;
	}
}

int main()
{
	init_int0();
	sei(); 		// Enable interrupts

	while(1) {	

		while(!flag);

		// Do with data from the remote control here what you like.
		flag = 0;
	}

	return 0;
}

External Links