SHT0_8不知道是怎么确定的

1万 · 2015-9-21 20:16

Description: Use ADC12 and the integrated temperature sensor to detect
//  temperature gradients. The temperature sensor output voltage is sampled
//  ~ every 80ms and compared with the defined delta values using an ISR.
//  (ADC12OSC/256)/ determines sample time which needs to be greater than
//  30us for temperature sensor.
//  ADC12 is operated in repeat-single channel mode with the sample and
//  convert trigger sourced from Timer_A CCR1. The ADC12MEM0_IFG at the end
//  of each converstion will trigger an ISR.
//  ACLK = n/a, MCLK = SMCLK = default DCO ~ 800k, ADC12CLK = ADC12OSC

#include <msp430.h>

#define ADCDeltaOn    12                // ~2 Deg C delta

static unsigned int FirstADCVal;          // holds 1st ADC result

int main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                // Stop watchdog
  P1OUT = 0x00;                            // Clear P1
  P1DIR = 0x01;                            // P1.0 as output
  ADC12CTL1 = SHS_1 + SHP + CONSEQ_2;    // TA trig., rpt conv.
  ADC12MCTL0 = SREF_1 + INCH_10;          // Channel A10, Vref+
  ADC12IE = 0x01;                         // Enable ADC12IFG.0
  ADC12CTL0 = SHT0_8 + REF2_5V + REFON + ADC12ON + ENC; // Config ADC12
  TACCTL1 = OUTMOD_4;                      // Toggle on EQU1 (TAR = 0)
  TACTL = TASSEL_2 + MC_2;                // SMCLK, cont-mode
  while (!(0x01 & ADC12IFG));             // First conversion?
  FirstADCVal = ADC12MEM0;                // Read out 1st ADC value
  _BIS_SR(LPM0_bits + GIE);                // Enter LPM0 w/ interrupt
}

#pragma vector=ADC12_VECTOR
__interrupt void ADC12ISR (void)
{
  if (ADC12MEM0 <= FirstADCVal + ADCDeltaOn)
   P1OUT &= ~0x01;                      // LED off
  else P1OUT |= 0x01;                      // LED on
}

我是个初学者，这个程序的其他地方还可以读懂，就是SHT0_8不知道是怎么确定的，请大神解答。