msp430x54x_adc12_02.c

MSP430的开发程序的例子+中文注释

//******************************************************************************
//  msp430FG5438 Demo - ADC12, Using the Internal Reference
//
//  Description: This example shows how to use the internal reference of ADC12.
//  It uses the internal 2.5V reference and performs a single conversion
//  on channel A0. The conversion results are stored in ADC12MEM0. Test by
//  applying a voltage to channel A0, then setting and running to a break point
//  at the "_NOP()" instruction. To view the conversion results, open an ADC12
//  register window in debugger and view the contents of ADC12MEM0.
//
//                msp430FG5438
//             -----------------
//            |                 |
//     Vin -->|P6.0/A0          |
//            |                 | 
//
//   M Smertneck
//   Texas Instruments Inc.
//   April 2008
//   Built with CCEv3.2 IAR Embedded Workbench Version: 3.42A
//******************************************************************************

#include <msp430x54x.h>

void main(void)
{
  volatile unsigned int i;
  WDTCTL = WDTPW+WDTHOLD;                   // Stop watchdog timer
  P6SEL |= 0x01;                            // Enable A/D channel A0
  ADC12CTL0 = ADC12ON+ADC12SHT02+ADC12REFON+ADC12REF2_5V;
                                            // Turn on and set up ADC12
  ADC12CTL1 = ADC12SHP;                     // Use sampling timer
  ADC12MCTL0 = ADC12SREF_1;                 // Vr+=Vref+

  for ( i=0; i<0x3600; i++);                // Delay for reference start-up
 
  ADC12CTL0 |= ADC12ENC;                    // Enable conversions

  while (1)
  {
    ADC12CTL0 |= ADC12SC;                   // Start conversion
    while ((ADC12IFG & BIT0)==0);
    _NOP();                                 // SET BREAKPOINT HERE
  }
}