Timer question on MC9S08DZ60

Denikar — Sun, 28 Nov 2010 23:36:04 GMT

Hi All,

I'm trying to setup a general purpose timer on the MC9S08DZ60. I do not want it tied to pin control as I have the pins assigned to other non-timer related I/O.

Below is a snippet of my code:

#define   TPM1CH0IRQTIME   400   // Set timer 1 freq to 100us

...

   /* Setup timer status and control register A
   b6 = 0 TOIE disable overflow interrupts
   b5 = 0 CPWMS no PWM mode
   b4:b3 CLKSB:CLKSA = 01 sets clock source to bus clock
   b2:b0 PS2S0 = 000 sets prescale to divide by 1 */
TPM1SC = 0x08;

   /* Enable irq on timer 1 channel 0

   Edge level bits set to 00
   MSB MSA bits set to 00 */
   TPM1C0SC = 0x40;

   /* Setup initial irq trigger time on timer 1 ch 0 */
   TPM1C0V = TPM1CNT + TPM1CH0IRQTIME;

   /* Clear any pending timer interrupts */
   TPM1SC &= 0x7F;
   TPM2SC &= 0x7F;

   TPM1C0SC &= 0x7F;
   TPM1C1SC &= 0x7F;
   TPM1C2SC &= 0x7F;
   TPM1C3SC &= 0x7F;
   TPM1C4SC &= 0x7F;
   TPM1C5SC &= 0x7F;

   TPM2C0SC &= 0x7F;
   TPM2C1SC &= 0x7F;

...

@interrupt void tpm1ch0_irq(void)
{
   /* Timer 1 channel 0 interrupt service routine
       Used to generate system base time
       Increments free running counter every 100us */

   /* Clear timer irq flag */
   TPM1C0SC &= 0x7F;

   TPM1C0V = TPM1CNT + TPM1CH0IRQTIME;   /* Reset trigger time */

   t100us++;                               /* Increment 100us timer */
   if(t100us >= 10)               /* Every 1ms (10*100us) */
   {
   /* Increment the free running 1msec counter, let it overflow */
   ulFreeRunningCounter++;
   if(ulFreeRunningCounter == 0)
       uwOverflowCounter++;   /* Overflow occurred, inc counter */
       t100us = 0;                       /* Reset t100us timer */
   }

}   /* end tpm1ch0_irq */

Problem is the irq will not fire at all. Any ideas as to why? Please note I am clearing the main interrupt flag (via CLI) prior to starting the main routine.

Thanks in advance.

Re: Timer question on MC9S08DZ60

kef — Mon, 29 Nov 2010 02:29:15 GMT

    /* Enable irq on timer 1 channel 0

   Edge level bits set to 00
   MSB MSA bits set to 00 */
   TPM1C0SC = 0x40;

MSB:MSA = 0:0 is input capture mode. You need output compare mode with timer channel not connected to pin. Output compare mode is selected when MSB:MSA=0:1 and ELSB:ELSA=0:0 disconnects pin from timer.

Re: Timer question on MC9S08DZ60

Denikar — Mon, 29 Nov 2010 06:03:15 GMT

That did it.

Thank you!

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