外接晶振问题

只看该作者 · 2013-1-19 13:07

//  MSP-FET430P140 Demo - Timer_A, Toggle P1.0, Overflow ISR, 32kHz ACLK
//
//  Description: Toggle P1.0 using software and the Timer_A overflow ISR.
//  In this example an ISR triggers when TA overflows. Inside the ISR P1.0
//  is toggled. Toggle rate is exactly 0.5Hz. Proper use of the TAIV interrupt
//  vector generator is demonstrated.
//  ACLK = TACLK = 32768Hz, MCLK = SMCLK = default DCO ~800kHz
//  //* An external watch crystal on XIN XOUT is required for ACLK *//
//
//          MSP430F149
//       ---------------
//    /|\|          XIN|-
//    | |             | 32kHz
//    --|RST       XOUT|-
//       |             |
//       |          P1.0|-->LED
//
//  M. Buccini
//  Texas Instruments Inc.
//  Feb 2005
//  Built with IAR Embedded Workbench Version: 3.21A
//******************************************************************************
#include  <msp430x14x.h>
void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                // Stop WDT
  P1DIR |= 0x01;                         // P1.0 output
  TACTL = TASSEL_1 + MC_2 + TAIE;          // ACLK, contmode, interrupt
  _BIS_SR(LPM3_bits + GIE);                // Enter LPM3 w/ interrupt
}
// Timer_A3 Interrupt Vector (TAIV) handler
#pragma vector=TIMERA1_VECTOR
__interrupt void Timer_A(void)
{
  switch( TAIV )//判断哪个产生中断
  {
case  2:  break;                      // CCR1 not used
case  4:  break;                      // CCR2 not used
case 10:  P1OUT ^= 0x01;             // overflow
            break;
  }
}