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Timer2 of 89S52 - the code dosen't seem to work

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lats

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89s52 timer2 problem

hi,
I'm trying to toggle a led's state on timer2 overflow interrupt. But the code dosen't seem to work. Frequency at which led blinks (blinking may not be even visible) is not important. Below is the code:-

Code: 
void timer2_ISR (void) interrupt 5 using 1	   
{
		OverFlowTimer2++;
	     

		if(OverFlowTimer2>=10)//1 seconds
	  	 	{
		  	 	OverFlowTimer2=0;
		  	 	TF2=0;
		  	 	led=!led;
			}

	  
}/////end of timer0_ISR











T2CON=0x00;
		T2MOD=0x01;
		TL2     = 0x00;   // Timer 2 low byte 
   		TH2     = 0xFF;   // Timer 2 high byte 
   		RCAP2L  = 0x00;   // Timer 2 reload capture register, low byte 
   		RCAP2H  = 0xFF;   // Timer 2 reload capture register, high byte 
		TR2 = 1;


& one thing more how will be the frequency calculated will it be Freq = Xtal Freq / (C*12 * 2)

waiting for your help.... thnx
 

Re: Timer2 of 89S52

you have to clear the timer overflow flag every time you are going in the interrupt
 

    L

    lats

    Points: 2
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Re: Timer2 of 89S52

Thanks for replying. Yes I think i had placed TF2=0 in wrong place i tried changing it to
Code: 
void timer2_ISR (void) interrupt 5 using 1	   //For LIM Mode
{
		OverFlowTimer2++;
	    TF2=0;
			if(OverFlowTimer2>=10)//1 seconds
	  	 	{
		  	 	OverFlowTimer2=0;
		  	 	led=!led;
			}

	  
}/////end of timer0_ISR

but still it's not working.
 

Re: Timer2 of 89S52

the interrupt part of the code seems correct
but did you enable the interrupts
because it is not shown in the code
 

    L

    lats

    Points: 2
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Timer2 of 89S52

Thanks a lot. It has started working. I missed setting ET2 bit. One thing more if you could help, do I have to sure use P1.1(T2EX), for autorelaod mode of Timer2, (I just wanted to save my I/o). Thanks a lot again. ;-) I clicked "helped me" both times :)

hey, One thing more, in the statement

Code: 
void timer2_ISR (void) interrupt 5 using 1

whats the use of "using 1"
 

Re: Timer2 of 89S52

using 1 is a referance to bank 1, if you do not have any push pop issues, you can remove it.


hock
 

    L

    lats

    Points: 2
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Re: Timer2 of 89S52

you can skip setting the P1.1(T2EX) for timer two
you can use it as an gpio

and as told by hock, using 1 is selecting specifically the register bank 1 in 8051
its a compiler directive
you can skip it no problem for a simple program
 

    L

    lats

    Points: 2
    Helpful Answer Positive Rating
Timer2 of 89S52

Thanks a lot once again. sau_sol do you check your private messages (here in your account)
 

Timer2 of 89S52

nice to c some revent information on following web pages.
**broken link removed**
and see also
**broken link removed**
 

Re: Timer2 of 89S52

lats said:
sau_sol do you check your private messages (here in your account)
Click to expand...

yes I checked it but there is nothing new
 

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