fet140_ta_hfxtal.c

msp430f14x 系列片内外设的实例代码

//******************************************************************************
//  MSP-FET430P140 Demo - Timer_A Toggle P1.0, overflow ISR, HF XTAL ACLK 
//
//  Description; Toggle P1.0 using software and the timer_A overflow ISR. 
//  In this example an ISR will trigger when TA overflows.  Inside the ISR P1.0 
//  is toggled.  Toggle rate is about 15 hz.
//  Proper use of TAIV interrupt vector generator demonstrated.
//  ACLK  = 8 Mhz, TACLK = 8/8 = 1 Mhz MCLK = SMCLK = DCO~ 800k
//  //*An external resonator on XIN XOUT is required for ACLK*//	  
//
//           MSP430F149
//         ---------------
//     /|\|            XIN|-  
//      | |               | 8Mhz
//      --|RST        XOUT|-
//        |               |
//        |           P1.0|-->LED
//
//  H. Grewal
//  Nov 2004
//  Updated for IAR Embedded Workbench Version: 2.21B
//******************************************************************************

#include <msp430x14x.h>

void main(void)
{ 
  volatile unsigned int i;
  WDTCTL = WDTPW + WDTHOLD;             // Stop WDT
  P1DIR |= 0x01;                        // P1.0 output
  
  P5DIR |= 0x10;                        // P5.4= output direction
  P5SEL |= 0x10;                        // P5.4= MCLK option select
  BCSCTL1 |= XTS;                       // ACLK= LFXT1 = HF XTAL

  do 
  {
  IFG1 &= ~OFIFG;                       // Clear OSCFault flag
  for (i = 0xFF; i > 0; i--);           // Time for flag to set
  }
  while ((IFG1 & OFIFG));               // OSCFault flag still set?                

  BCSCTL2 |= SELM_3;                    // MCLK= LFXT1 (safe)
  TACTL = TASSEL_1 + MC_2 + ID_3 + TAIE;// ACLK, contmode, /8, 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;
  }
}