Xbee & MSP430F2272 Choose Baud Rate Parameters

Other Parts Discussed in Thread: MSP430F2272

Hello,

I am interfacing a Xbee module with the UART RX of the MSP430F2272. I am receiving the API Frame of 14 bytes properly for some time. But after a little while, the UART of MSP430 gets out of sync with the Xbee and I am reading other parts of the packet instead of byte 11 and 12 where the data is stored constantly. I tried Oversampling, increasing the clock speed from 1MHz to 8MHz, but not much difference (un-synchronization still occurs). Any help is much appreciated.

**CODE**

void main(void)
{
   WDTCTL = WDTPW + WDTHOLD;   // Stop WDT
   BCSCTL1 = CALBC1_8MHZ;      // Set DCO
   DCOCTL = CALDCO_8MHZ;
  
   P1SEL = 0x00;
   P2SEL = 0x00;
   P3SEL = 0x30;   //P3.4,5 = USCI_A0 TXD/RXD
  
   P1DIR = 0x00;   //set columns P1.0-P1.3 as inputs
   P2DIR = 0x39;   //set rows P2.3 and P2.4, P2.0 for # pressed = LED on, and P2.5 Xbee0 DI0 as outputs
   P3DIR = 0xC0;   //set rows P3.6 and P3.7 as outputs
   P4DIR = 0x10;   //set P4.6 as fancontrol: fancontrol=0 (off); fancontrol=1 (on)

   P3OUT = 0x00;   //initialize output port to ground
   P2OUT = 0x00;
  
   __delay_cycles(800000);
   lcd_init();      //get the lcd booted up
  
  
  //RX Parameters
  UCA0CTL1 |= UCSSEL_2;                     //SMCLK
  UCA0BR0 = 0x34;                           //Prescaler = 8MHz/(16 x 9600) = 52 = 0x34
  UCA0BR1 = 0x00;                             
  UCA0MCTL = 0x11;                          //UCA0MCTL = UCBRFx | UCBRSx | UCOS16
                                              //UCBRFx (1st modulation stage) = 0001b
                                            //UCBRSx (2nd modulation stage) = 000b
                                            //UCOS16 (Oversampling mode) = 1b -> Enabled
  UCA0CTL1 &= ~UCSWRST;                     //**Initialize USCI state machine**
  IE2 |= UCA0RXIE;                          //Enable USCI_A0 RX interrupt
 
  while (1) {
     __bis_SR_register(CPUOFF + GIE);       //Enter LPM0 w/ interrupt
     if (dataReady == 1) {
         displayTemp();
     }
     //inputTemp();
     numkeypressed = 0;
  }
}

// Receive RXed character
#pragma vector=USCIAB0RX_VECTOR
__interrupt void USCI0RX_ISR(void)
{
 
     apiframe[j] = UCA0RXBUF;
     if (apiframe[0] == 0x7E) {
         data[j] = apiframe[j];
         if (j == 11) { 
            dh = data[j];
         }
         if (j == 12) { 
            dl = data[j];
            //dataReady = 1;
         }
     }
     if (j > sizeof apiframe - 1) {  
          dataReady = 1;
          j = 0;
          __bic_SR_register_on_exit(CPUOFF);        // Return to active mode
     }
     j++;  
}