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

[Kevin Neff]

Since I sent the initial message, I have verified that the processor
is getting a soft reset when the timer3 interrupt is raised with an
LCD screen...  a slightly more intuitive debugging output :)


On Mon, 17 Jan 2005, James Washer wrote:

> 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
> > 
> 
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