//******************************************************************************
//  MSP430x26x Demo - ADC12, Using an External Reference
//
//  Description: 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 and 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 debugger 
//  and view the contents of ADC12MEM0.
//
//
//               MSP430F261x/241x
//                ---------------
//               |               |
//        Vin -->|P6.0/A0        |
//               |               |
//        REF -->|VeREF+         |
//               |               |
//
//  B. Nisarga
//  Texas Instruments Inc.
//  September 2007
//  Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.42A
//******************************************************************************

#include  <msp430x26x.h>

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-software trigger
    while ((ADC12IFG & BIT0)==0);
    _NOP();                                 // SET BREAKPOINT HERE
  }
}