//******************************************************************************
//  MSP-FET430P140 Demo - Basic Clock, LPM3 Using WDT ISR, 32kHz ACLK
//
//  Description: This program operates MSP430 normally in LPM3, pulsing P1.0
//  at 4 second intervals. WDT ISR used to wake-up system. All I/O configured
//  as low outputs to eliminate floating inputs. Current consumption does
//  increase when LED is powered on P1.0. Demo for measuring LPM3 current.
//  ACLK= LFXT1/4= 32768/4, MCLK= SMCLK= default DCO
//  //* 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 CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.21A
//******************************************************************************

#include  <msp430x14x.h>

void main(void)
{
  BCSCTL1 |= DIVA_2;                        // ACLK/4 ACLK來(lái)自LX1=32 KHz
  WDTCTL = WDT_ADLY_1000;                   // WDT 1s/4 interval timer用作間隔定時(shí)器1000ms(1s)*4,看門狗功能不用,而用作定時(shí)器功能,可以產(chǎn)生中斷
  IE1 |= WDTIE;                             // Enable WDT interrupt
  P1DIR = 0xFF;                             // All P1.x outputs
  P1OUT = 0;                                // All P1.x reset
  P2DIR = 0xFF;                             // All P2.x outputs
  P2OUT = 0;                                // All P2.x reset
  P3DIR = 0xFF;                             // All P3.x outputs
  P3OUT = 0;                                // All P3.x reset
  P4DIR = 0xFF;                             // All P4.x outputs
  P4OUT = 0;                                // All P4.x reset
  P5DIR = 0xFF;                             // All P5.x outputs
  P5OUT = 0;                                // All P5.x reset
  P6DIR = 0xFF;                             // All P6.x outputs
  P6OUT = 0;                                // All P6.x reset

  while(1)
  {
    int i;
    _EINT();
    LPM3;               // Enter LPM3  低功耗3開(kāi)啟中斷 cpu停止了(以下程序不能進(jìn)行,等待激活,但是ACLK繼續(xù)活躍,看門狗定時(shí)器繼續(xù)工作
     P1OUT &= ~0x01;                        // Set P1.0 LED off
    for (i = 5000; i>0; i--);               // Delay
     P1OUT |= 0x01;                         // Clear P1.0 LED on
  }
}

#pragma vector=WDT_VECTOR
__interrupt void watchdog_timer (void)
{
    LPM3_EXIT;                 // Clear LPM3 bits from 0(SR)
}