Re: [Mspgcc-users] 100kHz xtal

[Steve Underwood]

Hi Garst,

Did you turn off the 12pF caps in the MCU? They are probably not the 
right thing for your 100kHz crystal. Also, what is your layout like? 
This oscillator is one of the lowest power consumers made to date, but 
the price is a little higher than usual sensitivity to layout. Make sure 
you have adequate ground plane around the crystal area. Run ground 
tracks around the two tracks from the crystal to the MCU. Be paranoid - 
it pays!

Regards,
Steve


Garst R. Reese wrote:

Hi folks, I have a 100kHz LF xtal drivin ACLK, but the following setup
is giving me pulses spaced 1ms apart. Has anybody had any experience
trying to use a 100kHz xtal instead of the usual 32kHz? It looks like
I'm getting a subharmonic.

Thanks,
 Garst 
void setup_timerA(void)
{
       unsigned temp;

       #ifdef _SHOW_YELLOW_LED_
       /*P1.6 is also connected to the IrDA CD pin*/
       P1SEL |= BV(6);
  P1DIR |= BV(6);

       #endif
       //Assumes ACLK = 100kHz, MCLK = 3.6864MHz

       // set up timer A for 250us SAMPCON to ADC12
       TACTL           = TASSEL_ACLK + MC_UPTO_CCR0;// + ID_DIV8;
       TACCR0  = 25;           //RESET when TAR==CCR0
       TACCR1  = 22;           //SET when TAR==CCR1
       TACCTL1 = OUTMOD_SET_RESET; //Mode 3: set_reset

       /*Start Timer*/
       TACTL |=        TACLR;
       TACTL &= ~TACLR;

}