msp430x22x4_adc10_02.c

如果有人学习单片机

//******************************************************************************
//  MSP430F22x4 Demo - ADC10, Sample A0, 1.5V Ref, Set P1.0 if A0 > 0.2V
//
//  Description: A single sample is made on A0 with reference to internal
//  1.5V Vref. Software sets ADC10SC to start sample and conversion - ADC10SC
//  automatically cleared at EOC. ADC10 internal oscillator times sample (16x)
//  and conversion. In Mainloop MSP430 waits in LPM0 to save power until ADC10
//  conversion complete, ADC10_ISR will force exit from LPM0 in Mainloop on
//  reti. If A0 > 0.2V, P1.0 set, else reset.
//
//                MSP430F22x4
//             -----------------
//         /|\|              XIN|-
//          | |                 |
//          --|RST          XOUT|-
//            |                 |
//        >---|P2.0/A0      P1.0|-->LED
//
//  P.Thanigai
//  Texas Instruments Inc.
//  August 2007
//  Built with Code Composer Essentials Version: 2.0
//******************************************************************************
#include "msp430x22x4.h"

void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                 // Stop WDT
  ADC10CTL0 = SREF_1 + ADC10SHT_2 + REFON + ADC10ON + ADC10IE;
  TACCR0 = 30;                              // Delay to allow Ref to settle
  TACCTL0 |= CCIE;                          // Compare-mode interrupt.
  TACTL = TASSEL_2 + MC_1;                  // TACLK = SMCLK, Up mode.
  __bis_SR_register(CPUOFF + GIE);          // LPM0, TA0_ISR will force exit
  TACCTL0 &= ~CCIE;                         // Disable timer Interrupt
  ADC10AE0 |= 0x01;                         // P2.0 ADC option select
  P1DIR |= 0x01;                            // Set P1.0 to output direction

  for (;;)
  {
    ADC10CTL0 |= ENC + ADC10SC;             // Sampling and conversion start
    __bis_SR_register(CPUOFF + GIE);        // LPM0, ADC10_ISR will force exit
    if (ADC10MEM < 0x88)                    // ADC10MEM = A0 > 0.2V?
      P1OUT &= ~0x01;                       // Clear P1.0 LED off
    else
      P1OUT |= 0x01;                        // Set P1.0 LED on
  }
}

// ADC10 interrupt service routine
__interrupt void ADC_ISR (void);
ADC10_ISR(ADC_ISR)
__interrupt void ADC_ISR (void)
{
  __bic_SR_register_on_exit(CPUOFF);        // Clear CPUOFF bit from 0(SR)
}

__interrupt void Timer_A(void);
TIMERA0_ISR(Timer_A)
__interrupt void Timer_A(void)
{
  TACTL = 0;
  LPM0_EXIT;                                // Exit LPM0 on return
}