//******************************************************************************
//  MSP430x24x Demo - ADC12, Sample A10 Temp and Convert to oC and oF
//
//  Description: A single sample is made on A10 with reference to internal
//  1.5V Vref. Software sets ADC12SC to start sample and conversion - ADC12SC
//  automatically cleared at EOC. ADC12 internal oscillator times sample
//  and conversion. In Mainloop MSP430 waits in LPM0 to save power until
//  ADC10 conversion complete, ADC12_ISR will force exit from any LPMx in
//  Mainloop on reti.
//  ACLK = n/a, MCLK = SMCLK = default DCO ~1.045Mhz, ADC12CLK = ADC12OSC
// 
//  Uncalibrated temperature measured from device to devive will vary do to
//  slope and offset variance from device to device - please see datasheet.
//
//                MSP430F249
//             -----------------
//         /|\|              XIN|-
//          | |                 |
//          --|RST          XOUT|-
//            |                 |
//            |A10              |
//
//  B. Nisarga
//  Texas Instruments Inc.
//  September 2007
//  Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.42A
//******************************************************************************

#include  <msp430x24x.h>

int long temp;
int long IntDegF;
int long IntDegC;

void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                 // Stop WDT
  ADC12CTL0 = SHT0_8 + REFON + ADC12ON;     // Internal ref = 1.5V
  ADC12CTL1 = SHP;                          // enable sample timer
  ADC12MCTL0 = SREF_1 + INCH_10;            // ADC i/p ch A10 = temp sense i/p
  ADC12IE = 0x001;                          // ADC_IFG upon conv result-ADCMEMO
  ADC12CTL0 |= ENC;

  while(1)
  {
    ADC12CTL0 |= ADC12SC;                   // Sampling and conversion start
    _BIS_SR(CPUOFF + GIE);                  // LPM0 with interrupts enabled

//  oF = ((x/4096)*1500mV)-923mV)*1/1.97mV = x*761/4096 - 468
//  IntDegF = (ADC12MEM0 - 2519)* 761/4096
    IntDegF = (temp - 2519) * 761;
    IntDegF = IntDegF / 4096;

//  oC = ((x/4096)*1500mV)-986mV)*1/3.55mV = x*423/4096 - 278
//  IntDegC = (ADC12MEM0 - 2692)* 423/4096
    IntDegC = (temp - 2692) * 423;
    IntDegC = IntDegC / 4096;

    _NOP();                                 // << SET BREAKPOINT HERE
  }
}

#pragma vector=ADC12_VECTOR
__interrupt void ADC12ISR (void)
{
    temp = ADC12MEM0;                       // Move results, IFG is cleared
    _BIC_SR_IRQ(CPUOFF);                    // Clear CPUOFF bit from 0(SR)
}