MSP430FR2355: Pulse oximeter with MSP430FR2355

 // Configure reference module
	         PMMCTL0_H = PMMPW_H;                    // Unlock the PMM registers
	         PMMCTL2 = INTREFEN | REFVSEL_2;         // Enable internal 2.5V reference
	         while(!(PMMCTL2 & REFGENRDY));          // Poll till internal reference settles




	        /*******************SAC0 configurations as TIA******************/
	         P1SEL0 |=   BIT2  ;             // Select  P1.2  OA0- PIN function
	         P1SEL1 |=   BIT2  ;             // Select  P1.2  OA0- PIN function

	         SAC0DAC = DACSREF_1;                        // Select 2.5V int Vref as DAC reference
	           SAC0DAT = 0x0FFF;                         // Set SAC DAC data to 2.5V
	           SAC0DAC |= DACEN;                         // Enable DAC
	         SAC0OA = NMUXEN + PMUXEN + PSEL_1 + NSEL_0; //Select positive INPUT AS DAC and negative pin input AS PHOTODIODE
	         SAC0PGA |= MSEL_0;                          // INVERTING PGA MODE
	         SAC0OA &= ~OAPM;                            // Select HIGH speed and HIGH power mode
	         SAC0OA |= SACEN + OAEN;                     // Enable SAC and OA

	         /****************SAC2 configurations AS INVERTING PGA************/
	                                 P3SEL0 |= BIT1    ;             // Select P3.1   OA2 OUTPUT function
	                                 P3SEL1 |= BIT1    ;             // Select P3.1   OA2 OUTPUT function

	                                 SAC2DAC = DACSREF_1;                       // Select 2.5V int Vref as DAC reference
	                                   SAC2DAT = 0x0FFF;                         // Set SAC DAC data to 2.5V
	                                   SAC2DAC |= DACEN;                         // Enable DAC
	                                 SAC2OA = NMUXEN + PMUXEN + PSEL_1 + NSEL_1;//Select positive INPUT AS DAC and negative pin input AS O/P of OA0
	                                 SAC2PGA |= GAIN0 + GAIN2 + MSEL_3;    // Set inverting PGA mode with Gain=16
	                                 SAC2OA &= ~OAPM;                           // Select HIGH speed and HIGH power mode
	                                 SAC2OA |= SACEN | OAEN; // Enable SAC and OA

 /******************SAC3 configurations AS DAC OUTPUT********************/
	                      P3SEL0 |= BIT5   ;           // Select P3.5  OA3O function
	                      P3SEL1 |= BIT5  ;         //  OA is used as buffer for DAC

	                      SAC3DAC = DACSREF_1;                       // Select 2.5V int Vref as DAC reference
	                      SAC3DAT = 3340;                         // Set SAC DAC data to INITIAL VALUE
	                      SAC3DAC |= DACEN;                         // Enable DAC
	                      SAC3OA = NMUXEN + PMUXEN + PSEL_1 + NSEL_0;//Select DAC MODE
	                      SAC3PGA |= MSEL_1;                       // Set OA AS BUFFER MODE
	                      SAC3OA &= ~OAPM;                           // Select HIGH speed and HIGH power mode
	                      SAC3OA |= SACEN | OAEN; // Enable SAC and OA

	                      /*******************SAC1 configurationsAS DAC OUTPUT**********************/
	                      P1SEL0 |= BIT5  ;            // Select P1.5  OA1O function
	                      P1SEL1 |= BIT5 ;          //  OA is used as buffer for DAC

	                     SAC1DAC = DACSREF_1;                       // Select 2.5V int Vref as DAC reference
	                     SAC1DAT = 3340;                         // Set SAC DAC data to INTIAL VALUE 
	                     SAC1DAC |= DACEN;                         // Enable DAC
	                     SAC1OA = NMUXEN + PMUXEN + PSEL_1 + NSEL_0;//Select DAC MODE
	                     SAC1PGA |= MSEL_1;                       // Set OA AS BUFFER MODE
	                     SAC1OA &= ~OAPM;                           // Select HIGH speed and HIGH power mode
	                    SAC1OA |= SACEN | OAEN; // Enable SAC and OA

	                    /***********ADC CONFIGURATION***********/

	         ADCCTL0 &= ~ADCENC;                       // Disable ADC
	       ADCCTL0 |= ADCSHT_4 | ADCMSC | ADCON;  //0000010010010010; 64 ADCLK CYCLES, MSC BIT HIGH, ADC ON

	       ADCCTL1 |= ADCSHP | ADCSHS_1 | ADCCONSEQ_1;   //0000010010010010;
	       ADCCTL2 &= ~ADCRES; //CLEAR RESOLUTION
	       ADCCTL2 |= ADCRES_2; //12 BIT RESOLUTION
	       ADCMCTL0 |= ADCSREF_1|ADCINCH_1|ADCINCH_3; // OA0 OUTPUT AS A1 ADC INPUT ,VR+= VREF+, ALSO OA2 OUPUT EXTERNALLY CONNECTED TO A3 ADC INPUT
	       ADCIE |= ADCIE0; // ENABLE CONVERSION COMPLETE INTERRUPT
	       ADCCTL0 |= ADCENC|ADCSC; // ENABLE CONVERSION & START  CONVERSION

	       /******************** Configure Timer ******************/

	       TB0CTL = TBSSEL__ACLK + TBCLR; //ACLK & Reset timer
	       TB0CCTL1 = OUTMOD_2; // TOGGLE & RESET
	       TB0CCTL0  = CCIE; //INTERRUPT ENABLE
           TB0CCR0 = 31; //SAMPLING RATE 512 SPS
           TB0CCR1 = 10; //Allow plenty of time for the signal to become stable before sampling
           TB0CTL |= MC_1; // UP MODE


// Timer B0 interrupt service routine
#pragma vector=TIMER0_B0_VECTOR
__interrupt void Timer0_B0_ISR(void)
{
int i;

 if((SAC3OA & SACEN)) //  CHECK IF VSLED IS ON

 {
     SAC3DAC |= DACEN;
     SAC3DAT = vs_LED_level;
     SAC0DAT = vs_dc_offset;
     is_IR = 0;                          // IR LED OFF

     ir_sample = ADCMEM0;              // Read the IR LED results
     i = ADCMEM0;
                                                 // Enable the next conversion sequence.
                                                 // The sequence is started by TA1
             ADCCTL0 &= ~ADCENC;
             ADCCTL0 |= ADCENC;

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