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need help with PWM,Interrupt and Timer0 coding in C language

 
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twiart



Joined: 03 Mar 2009
Posts: 1

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need help with PWM,Interrupt and Timer0 coding in C language
PostPosted: Tue Mar 03, 2009 12:40 pm     Reply with quote
I want to produce a frequency (I use PWM) for a certain period of time(timer0), then interrupt-on-overflow to stop the frequency for another period of time. So I should have tones play at certain interval. Below is my attempt on coding for that purpose and it isn't working...Please help me find where has gone wrong. Thanks !
Code:

/** I N C L U D E S **************************************************/
#include "p18f46k20.h"
#include "delays.h"
#include "12 CCP PWM.h"  // header file
#include "08 Interrupts.h"

/** V A R I A B L E S *************************************************/
#pragma udata   // declare statically allocated initialized variables


/** D E C L A R A T I O N S *******************************************/
void timer0(void);

#pragma code                            // declare executable instructions

void main (void)
{

 
   // set internal oscillator to 1MHz   
    //OSCCON = 0b10110110;                  // IRCFx = 101
    //OSCTUNEbits.PLLEN = 0;                //PLL disabled


//PWM settings for a frequency

   TRISDbits.TRISD7 = 0;            //PWM-pin ON
    T2CON  = 0b00000101;            //timer2 on
   PR2    = 240;
   CCPR1L = 0x78;
   CCP1CON= 0b01001100;
   
timer0();

while(1);
}


//---------------------------------------------------------------------------
void timer0(void)
{

T0CON=0b10100010;         //enable timer0
                     //timer is configured as 16-bits counter
                     //transition on TOCKl pin
                     //increment on low-high transition on T0CKl pin
                     //set prescaler               
                     //1:8 prescaler



   INTCONbits.TMR0IF = 0;          //clear roll-over interrupt flag
   INTCON2bits.INTEDG0=0;          // interrupt is falling edge
   INTCONbits.INT0IE=1;         // enable  interrupt
     INTCONbits.GIEH = 1;           //enable global interrupts
   
   TMR0H = 0;                      // clear timer - always write upper byte first
    TMR0L = 0;
}


//----------------------------------------------------------------------------
//Low priority interrupt vector

#pragma code InterruptVectorLow = 0x18
void
InterruptVectorLow (void)
{
  _asm
    goto InterruptHandlerLow
  _endasm
}


//-------------------------------------------------------------------------
// Low priority interrupt routine

#pragma code
#pragma interrupt InterruptHandlerLow
void
InterruptHandlerLow ()
{   
    if (INTCONbits.TMR0IF)
   {
        LATDbits.LATD7=0;
      Delay1KTCYx(10);
        INTCONbits.TMR0IF=0;
    }
}
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Tue Mar 03, 2009 12:50 pm     Reply with quote
This the CCS compiler forum. Please ask C18 compiler questions on
their forum:
http://www.microchip.com/forums/tt.aspx?forumid=3
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