fet430_adc12_01.c

msp430开发c语言例程

//******************************************************************************
//  MSP-FET430P430 Demo - ADC12 Sample A0 Set P5.1 if A0 > 0.5*AVcc 
//
//  Description; A single sample is made on A0 with reference to AVcc.  
//  Software sets ADC12SC to start sample and conversion - ADC12SC 
//  automatically cleared at EOC. ADC12 internal oscillator times sample (16x) 
//  and conversion. In Mainloop MSP430 waits in LPM0 to save power until ADC12
//  conversion is complete. ADC12_ISR forces exit from LPM0 in Mainloop on
//  reti. If A0 > 0.5*AVcc P5.1 is set, else it's reset. 
//  // For acurate conversion, bias ADC12 references per device datasheet //  
//  
//                MSP430FG439
//             -----------------
//         /|\|              XIN|-  
//          | |                 |
//          --|RST          XOUT|-
//            |                 |
//  0-AVcc >--|A0           P5.1|--> LED
//
//  M. Buccini
//  Texas Instruments, Inc
//  June 2004
//  Built with IAR Embedded Workbench Version: 2.21B
//******************************************************************************

#include  <msp430xG43x.h>

void main(void)
{ 
  WDTCTL = WDTPW + WDTHOLD;             // Stop WDT
  ADC12CTL0 = SHT0_2 + ADC12ON;         // Set sampling time, turn on ADC12
  ADC12CTL1 = SHP;                      // Use sampling timer
  ADC12IE = 0x01;                       // Enable interrupt
  ADC12CTL0 |= ENC;                     // Conversion enabled
  P6SEL |= 0x01;                        // P6.0 ADC option select 
  P5DIR |= 0x02;                        // P5.1 output
  
  for (;;)                              
  {
    ADC12CTL0 |= ADC12SC;               // Sampling open
    _BIS_SR(CPUOFF + GIE);              // LPM0, ADC12_ISR will force exit
  }
}

// ADC12 interrupt service routine
#pragma vector=ADC_VECTOR
__interrupt void ADC12_ISR (void)
{
    if (ADC12MEM0 < 0x7FF) 
      P5OUT &= ~0x02;                   // Clear P5.1 LED off
    else
      P5OUT |= 0x02;                    // Set P5.1 LED on
    _BIC_SR_IRQ(CPUOFF);                // Clear CPUOFF bit from 0(SR)
}