Launchpad stops when uart is operating

Other Parts Discussed in Thread: MSP430G2553

Hi!

I have a little problem what i can not solve by my self.

I running code on a Launchpad ver. 1.5 with msp430g2553 installed, i use msp430-gcc/mspdebug.

I want to keep the mcu in active mode at 16Mhz and the uart running at 9600 baud.

So a LED can blink while an interrupt service the communication.

It seems separately everything is just fine, but not the same time.

When i comment out " UCA0CTL1 &= ~UCSWRST;                     // **Initialize USCI state machine* " then the blinking appear, but of course there is no communication.

When i uncomment the above line, the communication works, but not the blinking.

However if is send many character via the terminal, the LED sometime change state.

I guessed the mcu goes lpm* when not servicing the interrupt, so the main program stops running, but i also tried it the 32k crystal installed on and changed the clock source. 

I got the same result...

Any help would be great!

This is my code:

#include <msp430.h>
#include <stdint.h>

uint8_t task_master = 0;
uint8_t serial_input=0;


int main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                 // Stop WDT
  P1DIR |= 0x01;
  BCSCTL1 = CALBC1_16MHZ;                    // Set DCO
  DCOCTL = CALDCO_16MHZ;
  P1SEL = BIT1 + BIT2 ;                     // P1.1 = RXD, P1.2=TXD
  P1SEL2 = BIT1 + BIT2 ;                    // P1.1 = RXD, P1.2=TXD
  UCA0CTL1 |= UCSSEL_2;                     // SMCLK
  UCA0BR0 = 0b10000010;                            // 16MHz 9600
  UCA0BR1 = 0b00000110;                              // 16MHz 9600
  UCA0MCTL = 0b00001100;                        //7-4:UCBRFx 3-1:UCBRSx 0:UCOS16

  UCA0CTL1 &= ~UCSWRST;                     // **Initialize USCI state machine**
  IE2 |= 0x03;                                                   //UCA0RXIE;                          // Enable USCI_A0 RX interrupt


  __bis_SR_register(GIE);       //  interrupts enableda


uint8_t in_buffer[64];
uint8_t in_buffer_pos = 0;


for(;;){
 UCA0TXBUF=0x75;
    volatile unsigned int i;

    P1OUT ^= 0x01;                          // Toggle P1.0 using exclusive-OR

    i = 500;                              // Delay
    do (i--);
    while (i != 0);

}
}

//  Echo back RXed character, confirm TX buffer is ready first
#pragma vector=USCIAB0RX_VECTOR
__interrupt void USCI0RX_ISR(void){

  serial_input=UCA0RXBUF;
  task_master=1;
 UCA0TXBUF=0x77;
  }



__interrupt void USCI0TX_ISR(void){


}