fet430_adc12_09.c

msp430开发c语言例程

//******************************************************************************
//  MSP-FET430P430 Demo - ADC12, Sequence of Conversions (non-repeated)
//              
//  This example shows how to perform A/D conversions on a sequence of channels.
//  A single sequence of conversions is performed - one conversion each on 
//  channels A0, A1, A2, and A3. Each conversion uses AVcc and AVss for the 
//  references. The conversion results are stored in ADC12MEM0, ADC12MEM1,
//  ADC12MEM2, and ADC12MEM3 respectively and are moved to 'results[]' upon
//  completion of the sequence. Test by applying voltages to pins A0, A1, A2, 
//  and A3, then setting and running to a break point at the "_BIC..." 
//  instruction in the ISR. To view the conversion results, open a watch window
//  in C-Spy and view 'results' or view ADC12MEM0, ADC12MEM1, ADC12MEM2, and 
//  ADC12MEM3 in an ADC12 SFR window.

//  Note that a sequence has no restrictions on which channels are converted. 
//  For example, a valid sequence could be A0, A3, A2, A4, A2, A1, A0, and A7.
//  See the MSP430x4xx User's Guide for instructions on using the ADC12.
//
//
//                MSP430FG439
//             -----------------
//            |                 |
//            |              A0 |<---- Vin0
//            |              A1 |<---- Vin1
//            |              A2 |<---- Vin2
//            |              A3 |<---- Vin3
//            |                 |
//
//
//  M.Mitchell
//  Texas Instruments, Inc
//  June 2004
//  Built with IAR Embedded Workbench Version: 2.21B
//******************************************************************************

#include          "msp430xG43x.h" // Standard Equations

static unsigned int results[4];         // Needs to be global in this example
                                        // Otherwise, the compiler removes it
                                        // because it is not used for anything.

void main(void)
{ 
  WDTCTL = WDTPW+WDTHOLD;               // Stop watchdog timer
  P6SEL = 0x0F;                         // Enable A/D channel inputs
  ADC12CTL0 = ADC12ON+MSC+SHT0_2;       // Turn on ADC12, set sampling time
  ADC12CTL1 = SHP+CONSEQ_1;             // Use sampling timer, single sequence
  ADC12MCTL0 = INCH_0;                  // ref+=AVcc, channel = A0
  ADC12MCTL1 = INCH_1;                  // ref+=AVcc, channel = A1
  ADC12MCTL2 = INCH_2;                  // ref+=AVcc, channel = A2    
  ADC12MCTL3 = INCH_3+EOS;              // ref+=AVcc, channel = A3, end seq.
  ADC12IE = 0x08;                       // Enable ADC12IFG.3
  ADC12CTL0 |= ENC;                     // Enable conversions
  _EINT();                              // Enable interrupts  

  while(1)
  {
    ADC12CTL0 |= ADC12SC;               // Start conversion
    _BIS_SR(LPM0_bits);                 // Enter LPM0 
  }
}

#pragma vector=ADC_VECTOR
__interrupt void ADC12ISR (void)
{
  results[0] = ADC12MEM0;               // Move results, IFG is cleared
  results[1] = ADC12MEM1;               // Move results, IFG is cleared
  results[2] = ADC12MEM2;               // Move results, IFG is cleared    
  results[3] = ADC12MEM3;               // Move results, IFG is cleared  
  _BIC_SR_IRQ(LPM0_bits);               // Clear LPM0, SET BREAKPOINT HERE
}