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Decode RC6 protocol using simple routine

 
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hayee



Joined: 05 Sep 2007
Posts: 252

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Decode RC6 protocol using simple routine
PostPosted: Thu Nov 25, 2010 5:52 am     Reply with quote

Hi guys i am sharing the code which i have developed for decoding RC6 protocol,hope it will be helpful for you

Code:

///////////////////////////////////////////////////////////////////////////////
//This code decode the RC6 signal.The signal is read on INT2 pin,whenever an //
//EXT interrupt comes, value of '1/2T' is loaded in timer0,whenever timer0   //                 
//overflows it will load the value of 'T' in the timer0 and read the status  //
//of the pin,this is done because it will be easy to check the status of the //
//pin in middle.if pin is low then 0 will be store in array then increament  //
//array position if pin is high then 1 will be store in array then increament//
//array position.when array position becomes 58, it means complete stream has// 
//arrived, so the timer0 will be disable and shows the result on             //
//hyperterminal.                                                             //
//whenever the EXT interrupt comes the above procedure will be repeated.     //
///////////////////////////////////////////////////////////////////////////////
#include <18f252.h>
#fuses HS,NOWDT,NOLVP,PUT,NOBROWNOUT                       
#use delay(clock=20000000)                                 
#use rs232(xmit=PIN_C6, rcv=PIN_C7, baud=9600)
                                                     
int1 a[58]={}; //array for storing the complete stream     
int flag=0,state,i,number;   
     
#int_TIMER0                                     
void timer0_interrupt(void)   
{                                                           
  clear_interrupt(int_TIMER0);
  enable_interrupts(int_TIMER0);
  set_timer0(65258);//value of T i-e 444 us                               
  if(!input(PIN_B2))                             
  {
    a[state]=0;//store 0 in array
    state++;   //increament the postion                                 
  }
  else if(input(PIN_B2))
  {
    a[state]=1;//store 1 in array
    state++;   //increament the postion                                 
  }       
  if(state>=58)//if stream is complete then disable the timer 0
  {
    disable_interrupts(INT_TIMER0);
    state=0;
    flag=1;
  }
}                                         
 
#int_EXT2                                 
void isr_ext2(void)       
{                                                       
  flag=0;                                                                     
  clear_interrupt(INT_TIMER0);
  enable_interrupts(INT_TIMER0);
  set_timer0(65397);//value of 1/2T i-e 222 us
}                                         

void main()                                   
{
  setup_timer_0(RTCC_INTERNAL | RTCC_DIV_8);//timer is in 16-bit mode,prescaler is 8
  ext_int_edge(2,H_TO_L);//when interrupt goes high to low (falling edge)     
  enable_interrupts(INT_EXT2);//enable int2                                         
  enable_interrupts(Global); //enable global interrupts                                         
  while(1)                                 
  {                   
    if(flag==1)           
    {           
      printf("\r\n\n");         
      for(i=0;i<58;i++)
      {                     
       printf(" %d ",a[i]);//print complete stream on pc
      }                   
      flag=2;               
    }
  }
}                     


you have captured the stream, now you can seprately store the start bit,toggle bits,address bits,data bits etc form the array.
arocholl



Joined: 14 Dec 2008
Posts: 21

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PostPosted: Thu Nov 25, 2010 8:47 am     Reply with quote

Quick suggestion: your enable_interrupts(INT_TIMER0); should be at the end of the ISR, not at the beginning. Otherwise you increase risk of reentrancy.
bkamen



Joined: 07 Jan 2004
Posts: 1530
Location: Central Illinois, USA

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PostPosted: Thu Nov 25, 2010 11:14 am     Reply with quote

Actually,

You don't need the Clear, Disable, Enable calls inside the Timer0 ISR.

That's dangerous and unneeded.

They need to be removed.

-Ben
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hayee



Joined: 05 Sep 2007
Posts: 252

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PostPosted: Thu Nov 25, 2010 10:58 pm     Reply with quote

Quote:
That's dangerous and unneeded

bkamen plz give me detail on "dangerous", would it be the same as arocholl said
Quote:
you increase risk of reentrancy

or there will be some more issues.
bkamen



Joined: 07 Jan 2004
Posts: 1530
Location: Central Illinois, USA

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PostPosted: Fri Nov 26, 2010 1:06 am     Reply with quote

hayee wrote:
Quote:
That's dangerous and unneeded

bkamen plz give me detail on "dangerous", would it be the same as arocholl said


I *think* he was talking about the INT_EXT2 ISR. (maybe not) I was talking about the timer0 ISR.

Unless you are somewhere defining the global interrupt handler, clearing, disabling,re-enabling is unneeded.

The CCS interrupt handler already clears the interrupt flag for you.. If I remember right - typically at the END of the ISR. You are clearing it in the beginning. This could cause the interrupt to fire again while it's being serviced.

You don't need to disable the interrupt while it's being serviced - thus, you don't need to re-enable it when exiting out.

Just remove it. It's unneeded and other people on this forum have described their projects not working when they do some combination if not exactly what you're doing.
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hayee



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Posts: 252

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PostPosted: Fri Nov 26, 2010 1:35 am     Reply with quote

Thanks bkamen,
Is it same for all types of interrupt or only for timer interrupts.
bkamen



Joined: 07 Jan 2004
Posts: 1530
Location: Central Illinois, USA

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PostPosted: Sat Nov 27, 2010 1:02 am     Reply with quote

hayee wrote:
Thanks bkamen,
Is it same for all types of interrupt or only for timer interrupts.


All interrupts have the "global interrupt handler" included whenever you define an ISR.


As soon as you say

Code:
#INT_xxx
void some_usr (void) {


}


CCS includes the global interrupt handler UNLESS you specifically include the a replacement for the global interrupt handler.

You can see it in ROM at the ISR Vector location when you view ROM after a compile.

This handler takes care of everything like clearing the interrupt bits that generated the interrupt.

Most of the time all the user's code ever needs to really do is define the interrupt and then enable/disable it -- BUT NOT IN THE INTERRUPT itself (unless you have a VERY specific reason to.. like use the INT_EXT to wake up the PIC after sleep -- but then disable the interrupt... and even that could be done after the sleep command when the PIC comes out of wakeup)

Before putting any interrupt manipulating commands in an ISR, it needs to be considered carefully as to "what will happen".
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hayee



Joined: 05 Sep 2007
Posts: 252

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PostPosted: Sat Nov 27, 2010 3:38 am     Reply with quote

as you said there is no need for enable/disable interrupt in the interrupt service routine, so i exactly do that
Code:

///////////////////////////////////////////////////////////////////////////////
//This code decode the RC6 signal.The signal is read on INT2 pin,whenever an //
//EXT interrupt comes, value of '1/2T' is loaded in timer0,whenever timer0   //                 
//overflows it will load the value of 'T' in the timer0 and read the status  //
//of the pin,this is done because it will be easy to check the status of the //
//pin in middle.if pin is low then 0 will be store in array then increament  //
//array position if pin is high then 1 will be store in array then increament//
//array position.when array position becomes 58, it means complete stream has// 
//arrived, so the timer0 will be disable and shows the result on             //
//hyperterminal.                                                             //
//whenever the EXT interrupt comes the above procedure will be repeated.     //
///////////////////////////////////////////////////////////////////////////////
#include <18f252.h>
#fuses HS,NOWDT,NOLVP,PUT,NOBROWNOUT                       
#use delay(clock=20000000)                                 
#use rs232(xmit=PIN_C6, rcv=PIN_C7, baud=9600)
                                                     
int1 a[58]={}; //array for storing the complete stream     
int flag=0,state,i,number;   
     
#int_TIMER0                                     
void timer0_interrupt(void)   
{                                                           
  set_timer0(65258);//value of T i-e 444 us                               
  if(!input(PIN_B2))                             
  {
    a[state]=0;//store 0 in array
    state++;   //increament the postion                                 
  }
  else if(input(PIN_B2))
  {
    a[state]=1;//store 1 in array
    state++;   //increament the postion                                 
  }       
  if(state>=58)//if stream is complete then disable the timer 0
  {
    state=0;
    flag=1;
  }
}                                         
 
#int_EXT2                                 
void isr_ext2(void)       
{                                                       
  flag=0;                                                                     
  set_timer0(65397);//value of 1/2T i-e 222 us
  enable_interrupts(INT_TIMER0);
}                                         

void main()                                   
{
  setup_timer_0(RTCC_INTERNAL | RTCC_DIV_8);//timer is in 16-bit mode,prescaler is 8
  ext_int_edge(2,H_TO_L);//when interrupt goes high to low (falling edge)     
  enable_interrupts(INT_EXT2);//enable int2                                         
  enable_interrupts(Global); //enable global interrupts                                         
  while(1)                                 
  {                   
    if(flag==1)           
    {           
      disable_interrupts(INT_TIMER0);
      printf("\r\n\n");         
      for(i=0;i<58;i++)
      {                     
       printf(" %d ",a[i]);//print complete stream on pc
      }                   
      flag=2;               
    }
  }
}   

Is that right?
bkamen



Joined: 07 Jan 2004
Posts: 1530
Location: Central Illinois, USA

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PostPosted: Sat Nov 27, 2010 9:24 am     Reply with quote

Excellent. Does that routine as written still work for you? (I'm assuming it does).


-Ben
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hayee



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PostPosted: Sun Nov 28, 2010 10:36 pm     Reply with quote

Yes the routine is working well
bkamen



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PostPosted: Mon Nov 29, 2010 12:24 pm     Reply with quote

Fabulous!
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sahu77



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Re: Decode RC6 protocol using simple routine
PostPosted: Sun Oct 16, 2011 1:23 pm     Reply with quote

hayee wrote:
Hi guys i am sharing the code which i have developed for decoding RC6 protocol,hope it will be helpful for you

Code:

///////////////////////////////////////////////////////////////////////////////
//This code decode the RC6 signal.The signal is read on INT2

  }
}                     


you have captured the stream, now you can seprately store the start bit,toggle bits,address bits,data bits etc form the array.


what need change for rc5 ? pl guide me here ...
_________________
sahu
Gabriel



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PostPosted: Tue Oct 18, 2011 7:56 am     Reply with quote

man... i swear CCS users have been reading my mind this past week... ethier asking the questions i have or developing similar code...

im developing a little widget to decode/clone ANY ir protocol...main interest is cloning....

i finished it monday night... as in: its working... but im still in the cleanup/optimize part that comes after working code....

already tried LG, Panasonic, Sony, and cable box remote... no problem.

its not as nice as this one though.... good job!
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sahu77



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PostPosted: Wed Oct 19, 2011 11:03 am     Reply with quote

wow very - very god job . im also think as just u think
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sahu
sahu77



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PostPosted: Sun Feb 03, 2013 9:57 am     Reply with quote

what need change for rc5 ? pl guide me here ...
!
!
!
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