Re: [avr-gcc-list] OVF3 Causes Reset?

[James Washer]

You sure you didn't want the LED off code to read

PORTF = PINF & (~B0)

 - jim

On Mon, 17 Jan 2005 14:26:58 -0600 (CST)
Kevin Neff <address@hidden> wrote:

> 
> I want a timer to interrupt my program periodically.  Below is the code
> for the interrupt hadler and the code that initilizes the timer.
> 
> To debug this code I am using an LED.  After a hard reset, the LED stays
> on for 8 seconds.  It is turned off at the end of the configuration
> function and stays off until the interrupt trips (~15 sec), at which
> point the LED turns on for 8 seconds.  My interpretation is that the
> configuration function is called again, which is only possible if the
> MCU is reset.
> 
> Any ideas on how to fix this?
> 
> 
> ----------
> 
> 
> 
> void configure_timer()
> {
> 
>   // LED on
>   DDRF = B0;
>   PORTF = B0;
>   delay( 8000 );
>                                                                               
>   
>   // write high byte first, writing the low byte latches data
>   TCNT3H = TIME_SLICE_LEN_H;
>   TCNT3L = TIME_SLICE_LEN_L;
>                                                                               
>   
>   // Enable timer interrupt.
>   TIMSK  = 0;
>   ETIMSK = B2;
>                                                                               
>   
>   // Configure Timer/Counter #3 for normal mode.  The timer increments
>   // and the counter is not cleared, it just overflows at 0xFFFF and
>   // continues at 0x0000.  TOV3 is set when TCCR3A = TCCR3B = 0.
>   //
>   // To configure the timer in normal mode, WGMn3..0 must be set to zero.
>   // WGMn3 and WGMn2 can be found in bits 4 and 3 of TCCRnB.  WGMn1 and
>   // WGMn1 can be found in bits 1 and 0 of TCCRnA.
>   TCCR3A = 0;
>   TCCR3B = 0;
> 
>   // Configure clock source for timer.  The clock source can be set using
>   // CS2..0, which can be found as bits 2, 1, and 0 of TCCRnB.
>   //
>   // Timer is on after this operation is executed.
>   TCCR3B |= B2 | B0;
>                                                                               
>   
>   // enable global interrupts
>   sei();
>             
>   // LED off                                                                  
>   
>   PORTF = 0;
>   delay( 1000 );
> }
> 
> 
> 
> 
> extern volatile uint8_t TIME_SLICE;
>                                                                               
>   
> SIGNAL( SIG_OVERFLOW3 )
> {
>   // LED on
>   PORTF = PINF | B0;
>                                                                               
>   
>   // write high byte first, writing the low byte latches data
>   TCNT3H = TIME_SLICE_LEN_H;
>   TCNT3L = TIME_SLICE_LEN_L;
>                                                                               
>   
>   if(  TIME_SLICE == SECTION1  )
>     TIME_SLICE = SECTION2;
>                                                                               
>   
>   else if(  TIME_SLICE == SECTION2  )
>     TIME_SLICE = SECTION3;
>                                                                               
>   
>   else if(  TIME_SLICE == SECTION3  )
>     TIME_SLICE = SECTION1;
>  
>   // LED off
>   PORTF = PINF & b0;
> }
> 
> 
> 
> 
> _______________________________________________
> avr-gcc-list mailing list
> address@hidden
> http://www.avr1.org/mailman/listinfo/avr-gcc-list
>