msp430x42x0_ta_04.c

msp430单片机系统开发子源码

//******************************************************************************
//   MSP430x42x0 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 handling the TAIV
//  interrupt vector is demonstrated.
//  ACLK = LFXT1 = 32768Hz, MCLK = SMCLK = default DCO = 32 x ACLK = 1048576Hz
//  //* An external watch crystal between XIN & XOUT is required for ACLK *//	
//
//           MSP430F4270
//         ---------------
//     /|\|            XIN|-
//      | |               | 32kHz
//      --|RST        XOUT|-
//        |               |
//        |           P1.0|-->LED
//
//  L. Westlund / S. Karthikeyan
//  Texas Instruments Inc.
//  June 2005
//  Built with IAR Embedded Workbench Version: 3.30A
//*****************************************************************************
#include  <msp430x42x0.h>

void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                 // Stop WDT
  FLL_CTL0 |= XCAP14PF;                     // Configure load caps
  P1DIR |= 0x01;                            // Set P1.0 to output direction
  TACTL = TASSEL_1 + MC_2 + TAIE;           // ACLK, cont. mode, 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 )
  {
    case  2:  break;                        // CCR1 not used
    case  4:  break;                        // CCR2 not used
    case 10:  P1OUT ^= 0x01;                // overflow
              break;
  }
}