fet140_ta08.c

msp430f14x 系列片内外设的实例代码

//******************************************************************************
//  MSP-FET430P140 Demo - Timer_A Toggle P1.0-3 CCRx Contmode ISR, 32kHz ACLK 
//
//  Description; Use timer_A CCRx units and overflow to generate four
//  independent timing intervals. For demonstration, CCR0, CCR1 and CCR2 output
//  units are optionally selected with port pins P1.1, P1.2 and P1.3 in toggle
//  mode. As such, these pins will toggle when respective CCRx registers match
//  the TAR counter. Interrupts are also enabled with all CCRx units,
//  software loads offset to next inderval only - as long as the interval offset
//  is aded to CCRx, toggle rate is generated in hardware. Timer_A overflow ISR 
//  is used to toggle P1.0 with software.   
//  ACLK = TACLK = 32kHz, MCLK = SMCLK = DCO ~ 800k 
//  As coded and with TACLK = 32768, toggle rates:
//  P1.1 = CCR0 = 32768/(2*4) = 4096Hz
//  P1.2 = CCR1 = 32768/(2*16) = 1024Hz
//  P1.3 = CCR2 = 32768/(2*100) = 163.84Hz
//  P1.0 = overflow = 32768/(2*65536) = 0.25Hz
//  Proper use of TAIV interrupt vector generator demonstrated.   
//  //*External watch crystal on XIN XOUT is required for ACLK*//	  
//
//           MSP430F149
//         ---------------
//     /|\|            XIN|-  
//      | |               | 32kHz
//      --|RST        XOUT|-
//        |               |
//        |           P1.1|--> CCR0
//        |           P1.2|--> CCR1
//        |           P1.3|--> CCR2
//        |           P1.0|--> overflow/software
//
//  M.Buccini
//  Texas Instruments, Inc
//  September 2003
//  Built with IAR Embedded Workbench Version: 1.26B
//  December 2003
//  Updated for IAR Embedded Workbench Version: 2.21B
//******************************************************************************

#include  "msp430x14x.h"

void main(void)
{ 
  WDTCTL = WDTPW + WDTHOLD;             // Stop WDT
  P1SEL |= 0x0E;                        // P1.1 - P1.3 option select
  P1DIR |= 0x0F;                        // P1.0 - P1.3 outputs
  CCTL0 = OUTMOD_4 + CCIE;              // CCR0 toggle, interrupt enabled
  CCTL1 = OUTMOD_4 + CCIE;              // CCR1 toggle, interrupt enabled
  CCTL2 = OUTMOD_4 + CCIE;              // CCR2 toggle, interrupt enabled
  TACTL = TASSEL_1 + MC_2 + TAIE;       // ACLK, contmode, interrupt enabled

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

// Timer A0 interrupt service routine
#pragma vector=TIMERA0_VECTOR
__interrupt void Timer_A0 (void)
{
  CCR0 += 4;                            // Add Offset to CCR0
}

// Timer_A3 Interrupt Vector (TAIV) handler
#pragma vector=TIMERA1_VECTOR
__interrupt void Timer_A1(void)
{
  switch( TAIV )
  {
  case  2: CCR1 += 16;                  // Add Offset to CCR1
           break;
  case  4: CCR2 += 100;                 // Add Offset to CCR2
           break;                              
  case 10: P1OUT ^= 0x01;               // Timer_A3 overflow
           break;
 }
}