Posted on November 18, 2003 at 13:29 hi !
i'm using the st72264 with the in dart and i encounter jitter which is un acceptional while using output compare function or even the PWM
function.
i measure time and when the time is over i toggle a pin (PB2) with a desire fix frequency.
the jitter comes up every time the S/W has to deal with the toggle of the pin, let me explain, when i use the PWM function with OLV1 != OLV2 i get a fixed no jitter signal, but when i use the INT for toggling the bit (and with output compare )a jitter appears.
i added the basic application :
void main(void)
{
PBDDR = 0xFF;
PBOR = 0XFF; //
/* PORTS_Init(); // init ports */
ClrBit(PADDR,5); // set Port A, 5 and 7 pins as floating input
ClrBit(PADDR,7);
ClrBit(PAOR,5);
ClrBit(PAOR,7);
PCDDR |= 0x04;
PCOR |= 0x04;
MISCR1 |=0x20;
/* using the output compare */
TBCLR = 0 ; // reset the counter
TBCR1 = OCIE ;
TBCR2 = Fcpu8 ;
TBOC1HR = 0;
TBOC1LR = 100;
asm (''rim'');
while(1) {
}
} // main loop
interrupt 8 void TIMER_B_INT (void)
{
unsigned char temp=0;
asm (''sim'');
temp=TBSR;
if (temp & OCF1)
{
TBCLR = 0 ; // reset the counter
TBOC1HR = 0;
TBCR1 = OCIE ;
TBCR2 = Fcpu8 ;
TBOC1LR = 100;
if (ValBit(Data,j))
PBDR|=0x04;
else
{
PBDR &= 0b11111011;
}
j++;
if (j==9)
j=1;
}
asm (''rim'');
}
and i attached an oscilloscope picture,
what could be the problem ???????
adi.
[ This message was edited by: Bamba on 18-11-2003 18:01 ]
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