//******************************************************************************
//  MSP430F20xx Demo - Timer_A, Toggle P1.0, CCR0 Up Mode ISR, 32kHz ACLK
//
//  Description: Toggle P1.0 using software and the TA_0 ISR. Timer_A is
//  configured for up mode, thus the the timer overflows when TAR counts
//  to CCR0. In this example, CCR0 is loaded with 1000-1.
//  Toggle rate = 32768/(2*1000) = 16.384Hz
//  ACLK = TACLK = 32768Hz, MCLK = SMCLK = DCO
//  //* An external watch crystal on XIN XOUT is required for ACLK *//  
//
//           MSP430F20xx
//         ---------------
//     /|\|            XIN|-
//      | |               | 32kHz
//      --|RST        XOUT|-
//        |               |
//        |           P1.0|-->LED
//
//  M. Buccini / L. Westlund
//  Texas Instruments Inc.
//  September 2005
//  Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.40A
//******************************************************************************

#include  <msp430x20x3.h>

void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                 // Stop WDT
  P1DIR |= 0x01;                            // P1.0 output
  CCTL0 = CCIE;                             // CCR0 interrupt enabled
  CCR0 = 1000-1;
  TACTL = TASSEL_1 + MC_1;                  // ACLK, upmode

  _BIS_SR(LPM3_bits + GIE);                 // Enter LPM3 w/ interrupt
}

// Timer A0 interrupt service routine
#pragma vector=TIMERA0_VECTOR
__interrupt void Timer_A (void)
{
  P1OUT ^= 0x01;                            // Toggle P1.0
}