UART communication with oxygen sensor with msp430 launchpad

ox_sensor_launchpad.c

#include <stdlib.h>
#include <string.h>
#include "msp430.h"

#define TXD BIT2
#define RXD BIT1

unsigned int CV = 0;
unsigned int DV = 0;
unsigned int RO = 0;
double oxygen = 15; // assign a value greater than 2
char oxygenData[6];

//void setClock(void){
//  CSCTL0_H = 0xA5;
//  CSCTL1 |= DCOFSEL0 + DCOFSEL1;             // Set max. DCO setting
//  CSCTL2 = SELA_3 + SELS_3 + SELM_3;        // set ACLK = XT1; MCLK = DCO
//  CSCTL3 = DIVA_3 + DIVS_0 + DIVM_0;        // set all dividers
//}

void setUart(void){

  // Configure UART pins
//  P1SEL |= TXD + RXD;
//  P1SEL2 |= TXD + RXD;
//  // Configure UART 0
//  UCA0CTL1 |= UCSWRST;
//  UCA0CTL1 = UCSSEL_2;                      // Set ACLK = 32768 as UCBRCLK
//  UCA0BR0 = 27;                              // 9600 baud
//  UCA0BR1 = 0;
//  UCA0MCTL = UCBRS2 + UCBRS0;                      // 32768/9600 - INT(32768/9600)=0.41
//                                            // UCBRSx value = 0x53 (See UG)
//  UCA0CTL1 &= ~UCSWRST;                     // release from reset
//  //UCA0IE |= UCRXIE;                         // Enable RX interrupt
////  IE2 |= UCA0RXIE;
//  UC0IE |= UCA0RXIE;
  
    DCOCTL = 0; // Select lowest DCOx and MODx settings
   BCSCTL1 = CALBC1_1MHZ; // Set DCO
   DCOCTL = CALDCO_1MHZ;
   P2DIR |= 0xFF; // All P2.x outputs
   P2OUT &= 0x00; // All P2.x reset
   P1SEL |= RXD + TXD ; // P1.1 = RXD, P1.2=TXD
   P1SEL2 |= RXD + TXD ; // P1.1 = RXD, P1.2=TXD
   P1OUT &= 0x00;
   UCA0CTL1 |= UCSSEL_2; // SMCLK
   UCA0BR0 = 26; // 1MHz 115200
   UCA0BR1 = 0x00; // 1MHz 1152
//   UCA0MCTL = UCBRS2 + UCBRS0; // Modulation UCBRSx = 5
   UCA0MCTL = 0;
   UCA0CTL1 &= ~UCSWRST; // **Initialize USCI state machine**
   UC0IE |= UCA0RXIE; // Enable USCI_A0 RX interrupt
}

void setPorts(void) {
  P2DIR |= 0xFF;
  P2OUT &= 0x00;
  P1OUT &= 0x00;
//  P1DIR |= TXD;
//  P1DIR &= ~RXD;
  P1DIR |= BIT3 + BIT4;
  P1OUT &= ~(BIT3 + BIT4);
}
// check oxygen levels and set specific ports.
void checkOxygen(double oxygen){
  if(oxygen > 2) {
    RO = 1;
    P1OUT |= BIT3;
    P1OUT |= BIT4;
  } else {
    RO = 0;
    P1OUT &= ~BIT3;
    P1OUT &= ~BIT4;
  }
}

// Get the oxygen data from receive buffer
double getOxygen() {
  int i = 0;

  oxygenData[0] = UCA0RXBUF; // get first byte
  for(i = 1; i < 5; i++) { // get the remaining 4 bytes
    while (!(IFG2&UCA0RXIFG));
    oxygenData[i] = UCA0RXBUF;
  }
  oxygenData[5] = '\0';

  return atof(oxygenData);
}


int main(void){
  WDTCTL = WDTPW + WDTHOLD;                 // stop watchdog


  setPorts();
//  setClock();
  setUart();
 // __delay_cycles(2000);
  __bis_SR_register(GIE);
  while(1) {}

}

#pragma vector=USCIAB0RX_VECTOR
__interrupt void USCI0RX_ISR(void)
{
   // UCA0IFG &=~ UCRXIFG;                      // Clear interrupt
   oxygen = getOxygen();
//   printf("%3.2f\n",oxygen);
   checkOxygen(oxygen);
 }