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Door Access Application?

 
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chingB



Joined: 29 Dec 2003
Posts: 81

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Door Access Application?
PostPosted: Tue Mar 09, 2004 4:47 pm     Reply with quote
Hi,

I have access application and I put a micro-switch such that when the door is open it will closed. How can I monitor the door if it is open for 20seconds it sound an alarm?

Would it be possible to use interrupt?


Thanx
asjad



Joined: 09 Mar 2004
Posts: 52
Location: Greater Manchester - UK

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Door switch
PostPosted: Tue Mar 09, 2004 4:53 pm     Reply with quote
You could use an external interrupt, which could start timer 0.

After say 10 seconds had elaspsed on the timer0. you could sound an alarm

Hope this helps!!
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chingB



Joined: 29 Dec 2003
Posts: 81

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Re: Door switch
PostPosted: Tue Mar 09, 2004 5:10 pm     Reply with quote
asjad wrote:
You could use an external interrupt, which could start timer 0.

After say 10 seconds had elaspsed on the timer0. you could sound an alarm

Hope this helps!!


Is this algorithm will do the job or maybe share some tips and suggestions to improve this code.

Code:

#int_ext2
ext2_isr(){
   flag=1;
   doortmr=0;
   int2if=0;
}

main(){

   intedg2=1;
   int2if=0;
   enable_interrupts(int_ext2);
   enbale_interrupts(global);

   while(1){
      if (bit_test(PORTA,2) && (doortmr>=20))
         sound_alarm(ON);
      if (!bit_test(PORTA,2) && flag){
         sound_alarm(OFF); flag=0;
      }
   }
}


Thank u.
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