fet440_adc12_04.c

MSP430F43x, MSP430F44x.zip c语言 例程

//******************************************************************************
//  MSP-FET430P440 Demo - ADC12, Extend Sampling Period with SHT Bits
//
//  This example shows how to extend the sampling time using the sampling
//  timer. In this example, the ADC12OSC is used to provide the sampling period
//  and the SHT0 bits are set to extend the sampling period to 4xADC12CLKx256.
//  A single conversion is performed on channel A0. The A/D conversion results
//  are stored in ADC12MEM0 and are moved to 'results' upon completion of the
//  conversion. Test by setting and running to a break point at the "_NOP()"
//  instruction in the ISR. To view the conversion results, open a watch window
//  with the debugger and view 'results.'
//  ACLK = n/a, MCLK = SMCLK = default DCO, ADC12CLK = ADC12OSC
//
//
//                MSP430F449
//             ---------------
//            |               |
//     Vin -->|P6.0/A0        |
//            |               |
//
//  M. Mitchell
//  Texas Instruments Inc.
//  Feb 2005
//  Built with IAR Embedded Workbench Version: 3.21A
//******************************************************************************
#include  <msp430x44x.h>

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

void main(void)
{
  WDTCTL = WDTPW+WDTHOLD;                   // Stop watchdog timer
  P6SEL |= 0x01;                            // Enable A/D channel A0
  ADC12CTL0 = ADC12ON+SHT0_15;              // Turn on ADC12, set sampling time
  ADC12CTL1 = SHP;                          // Use sampling timer, set mode
  ADC12IE = 0x01;                           // Enable ADC12IFG.0
  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 = ADC12MEM0;                      // Move results, IFG is cleared
  _BIC_SR_IRQ(LPM0_bits);                   // Clear LPM0
  _NOP();                                   // SET BREAKPOINT HERE
}