Re: General question about IR remote signals from USB DVB tuner

[Jan Panteltje <panteltje@yahoo.com>]

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This little demo C program looks for the IR input device,
parses the IR output and can start any application on any remote key press
or release.
Compile with gcc -o test50 test50.c
I have added a start xterm, a start firefox, and a kill firefox
as example.
add your own as needed.
Have fun:-)


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/*
Copyright Jan Panteltje 2012-always
released under the GPL.
This is a small program that grabs keys from the Terratec Cinergy S2 USB HD remote and starts some applications.
This just demo code, no special purpose,
but it shows that little remote can be used to do anything your PC can do, not just TV.
Should be easy to adapt this for other DVB IR remote controllers.
You can find the key values by pressing the keys on the remote and watching the output of this program,
then add your own code for each key press and release as needed.

filename test50.c
compile with: gcc -o test50 test50.c
run with:
./test50
pres keys on IR remote,
key '1' starts an xterm
ENTER starts firefox
key 2 kills firefox
*/


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <sys/time.h>
#include <signal.h>
#include <pwd.h>
#include <math.h>
#include <time.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <sys/poll.h>
#include <stdint.h>
#include <locale.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/io.h>
#include <sys/ioctl.h>
#include <ctype.h>
#include <linux/dvb/frontend.h>
#include <linux/dvb/dmx.h>

#include <linux/input.h>

/*
looking for something like:
/dev/input/by-path/pci-0000:04:00.0-event-ir
*/


int main(int argc, char **argv)
{
int a, b, c, i, j;
int fd;
FILE *fptr;
int data[1024];
char temp[1024];
char ir_device[1024];
FILE *pptr;
int found_flag = 0;
int key_code, key_pressed;

/* going to parse the result of ls in /dev/input/by-path/ */
pptr = popen("ls --color=none /dev/input/by-path/", "r");
temp[0] = 0;
j = 0;
for(i = 0; i < 1024; i++)
	{
	c = fgetc(pptr);
	if( feof(pptr) )
		{
		ir_device[i] = 0;
		break;
		}	

	if(c == 10) // LF
		{
		temp[j] = 0;
		j = 0;
		if(strstr(temp, "event-ir") != 0)
			{
//			fprintf(stderr, "found it, i=%d temp=%s\n", i, temp);
			found_flag = 1;
			break;
			}
		j = 0;				
		}
	else
		{
		temp[j] = c;
		j++;
		}
	}
pclose(pptr);

if(! found_flag)
	{
	fprintf(stderr, "could not find event-ir device, aborting.\n");
	
	exit(1);
	}

//fprintf(stderr, "temp=%s\n", temp);

sprintf(ir_device, "/dev/input/by-path/%s", temp);
fprintf(stderr, "trying ir_device=%s\n", ir_device);

fptr = fopen(ir_device, "r");
if(! fptr)
	{
	fprintf(stderr, "could not open /dev/input/event13 for read,aborting.\n");
	
	exit(1);
	}

/* grab the device for us alone, this prevents output to other applications, as that would cause havoc */
a = ioctl(fileno(fptr), EVIOCGRAB);
if(a < 0)
	{
	fprintf(stderr, "ioctl EVIOCGRAB failed because ");
	perror("");
	
	exit(1);
	}

//fprintf(stderr, "fptr=%p\n", fptr);

/*
read the correct number of bytes from the device for one key event.
**** NOTE: this number 48 is empirical and works for my TerratecCinery S2 USB remote, other remotes may perhaps require  adifferent value. ****
maybe read it with an ioctlfrom input_keymap_entry ? see /usr/include/linux/input.h 
*/

FILE *pptr1;
FILE *pptr2;

while(1)
	{
	for(i = 0; i < 48; i++)
		{
		c = fgetc(fptr);
		if(feof(fptr) )break;

		/*
		field 18 has the key value 
		field 20 has the key pressed- released flag
		*/ 
		if(i == 18) key_code = data[18];
		if(i == 20) key_pressed = data[20];

		data[i] = c;	
		} /* end for eachbyte in a field */

	do_keys(key_code, key_pressed);
		
	fprintf(stderr, "\n");
	} /*end while read fields resulting from akey press */

exit(0);
} /* end function main */
	


do_keys(int key_code, int key_pressed)
{
FILE *pptr;

/* do your things here, this can be used to do anything on a key press and key release, just some silly examples */
if(key_pressed)
	{
	fprintf(stderr, "key %02x pressed\n", key_code);

	switch(key_code)
		{
		case 0x02: // key '1'
			popen("xterm", "w");
			/* no pclose, exiting xterm will do that */  
		break;
					
		case 0x60: // ENTER
			popen("firefox &", "w");
			break;
				
		}


	} /* end if key pressed */
else
	{		
	fprintf(stderr, "key %02x released\n", key_code);		
		
	switch(key_code)
		{
		case 0x03: // key '2'			
			popen("killall -KILL firefox-bin", "r");
			break;
		}

	} /* andif key released */

} /* end function do_keys */