//******************************************************************************
//  MSP430P249 Demo - Timer_B, Toggle P1.0, CCR0 Cont. Mode ISR, DCO SMCLK
//
//  Description: Toggle P1.0 using software and TB_0 ISR. Toggles every
//  50000 SMCLK cycles. SMCLK provides clock source for TBCLK.
//  During the TB_0 ISR, P1.0 is toggled and 50000 clock cycles are added to
//  CCR0. TB_0 ISR is triggered every 50000 cycles. CPU is normally off and
//  used only during TB_ISR.
//  ACLK = n/a, MCLK = SMCLK = TBCLK = default DCO ~1.045Mhz
//
//           MSP430F249
//         ---------------
//     /|\|            XIN|-
//      | |               |
//      --|RST        XOUT|-
//        |               |
//        |           P1.0|-->LED
//
//  B. Nisarga
//  Texas Instruments Inc.
//  September 2007
//  Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.42A
//******************************************************************************

#include  <msp430x24x.h>

void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                 // Stop WDT
  P1DIR |= 0x01;                            // P1.0 output
  TBCCTL0 = CCIE;                           // CCR0 interrupt enabled
  TBCCR0 = 50000;
  TBCTL = TBSSEL_2 + MC_2;                  // SMCLK, contmode

  _BIS_SR(LPM0_bits + GIE);                 // Enter LPM0 w/ interrupt
}

// Timer B0 interrupt service routine
#pragma vector=TIMERB0_VECTOR
__interrupt void Timer_B (void)
{
  P1OUT ^= 0x01;                            // Toggle P1.0
  TBCCR0 += 50000;                          // Add Offset to CCR0 [Cont mode]
}