#include <msp430g2553.h>
                                                       // Hardware-related definitions
#define UART_TXD 0x02                                  // TXD on P1.1 (Timer0_A.OUT0)
#define UART_TBIT (1000000 / 9600)                     // 9600 Baud, SMCLK = 1MHz
                                                       // Globals for transmit UART communication
unsigned int txData;                                   // UART internal variable for TX

void TimerA_UART_tx(unsigned char byte);               // Function prototypes
void TimerA_UART_print(char *string);

void main(void){

  WDTCTL = WDTPW + WDTHOLD;                            // Stop watchdog timer
  DCOCTL = 0x00;                                       // Set DCOCLK to 1MHz
  BCSCTL1 = CALBC1_1MHZ;
  DCOCTL = CALDCO_1MHZ;

  P1OUT = UART_TXD;                                    // Initialize P1.1
  P1SEL = UART_TXD;                                    // Timer function for TXD pin
  P1DIR = UART_TXD;                                    // Set TXD pin to output

                                                       // Timer_A for transmit UART operation
  TA0CCTL0 = OUT;                                      // Set TXD Idle as Mark = '1'
  TA0CCTL1 = SCS + CM1 + CAP;                          // Sync, Neg Edge, Capture
  TA0CTL = TASSEL_2 + MC_2;                            // SMCLK, start in continuous mode

  _BIS_SR(GIE);                                        // Enable CPU interrupts

  TimerA_UART_print("G2553 TimerA UART\r\n");          // Send test message
  TimerA_UART_print("READY.\r\n");
}

void TimerA_UART_tx(unsigned char byte) {              // Outputs one byte using the Timer_A UART

  while (TACCTL0 & CCIE);                              // Ensure last char got TX'd

  TA0CCR0 = TAR;                                       // Current state of TA counter
  TA0CCR0 += UART_TBIT;                                // One bit time till first bit
  txData = byte;                                       // Load transmit data, e.g. 'A'=01000001
  txData |= 0x100;                                     // Add mark stop bit, e.g. 101000001
  txData <<= 1;                                        // Add space start bit, e.g. 1010000010
  TA0CCTL0 = OUTMOD0 + CCIE;                           // Set TXD on, enable counter interrupt
}

void TimerA_UART_print(char *string) {                 // Prints a string using the Timer_A UART

  while (*string)
    TimerA_UART_tx(*string++);
}