fet430_adc12_03.c

msp430开发c语言例程

//******************************************************************************
//  MSP-FET430P430 Demo - ADC12, Using an External Reference 
//
//  This example shows how to use an external positive reference for the ADC12.
//  The external reference is applied to the VeREF+ pin. AVss is used for the
//  negative reference. A single conversion is performed 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 SFR window in C-Spy and
//  view the contents of ADC12MEM0.
//
//
//               MSP430FG439
//             ---------------
//            |               |
//            |      A0 (P6.0)|<---- Vin
//            |               |
//  REF ----->| VeREF+        |
//            |               |
//
//  M.Mitchell
//  Texas Instruments, Inc
//  June 2004
//  Built with IAR Embedded Workbench Version: 2.21B
//******************************************************************************

#include         "msp430xG43x.h"        // Standard Equations

void main(void)
{ 
  WDTCTL = WDTPW+WDTHOLD;               // Stop watchdog timer
  P6SEL |= 0x01;                        // Enable A/D channel A0
  ADC12CTL0 = ADC12ON+SHT0_2;           // Turn on ADC12, set sampling time
  ADC12CTL1 = SHP;                      // Use sampling timer
  ADC12MCTL0 = SREF_2;                  // Vr+ = VeREF+ (external)
  ADC12CTL0 |= ENC;                     // Enable conversions
   
  while (1)
  { 
    ADC12CTL0 |= ADC12SC;               // Start conversion
    while ((ADC12IFG & ADC12BUSY)==0);
    _NOP();                             // SET BREAKPOINT HERE
  }                           
}