#include <msp430.h>

#include <stdint.h>

int main(void)
{
        uint16_t n, p;

        WDTCTL = WDTPW | WDTHOLD;

#if 0
        BCSCTL1 = CALBC1_1MHZ;
        DCOCTL = CALDCO_1MHZ;
        BCSCTL2 = SELM_0 | DIVM_0 | DIVS_0;             /* MCLK = SMCLK = DCO */

        UCA0CTL1 |= UCSWRST;
        UCA0CTL1 |= UCSSEL_3;

        UCA0BR1 = 0;                                    /* 1,000,000 / 115200 */
        UCA0BR0 = 9;
        UCA0MCTL |= UCBRS_1;
#else

        BCSCTL1 = CALBC1_16MHZ;
        DCOCTL = CALDCO_16MHZ;
        BCSCTL2 = SELM_0 | DIVM_0 | DIVS_0;             /* MCLK = SMCLK = DCO */

        UCA0CTL1 |= UCSWRST;
        UCA0CTL1 |= UCSSEL_3;                           /* BRCLK = SMCLK */

        UCA0BR1 = 0;                                    /* 16,000,000 / 115,200 */
        UCA0BR0 = 138;
        UCA0MCTL |= UCBRS_7;
#endif

        UCA0CTL1 &= ~UCSWRST;
        P1DIR = BIT3 | BIT4 | BIT6 | BIT7;
        P1REN = BIT0;                                   /* Pull-up for IR, RXD; pull-down for Flow Control */
        P1OUT = BIT0;                                   /* Pull up, serial idle high */
        P1SEL = BIT0 | BIT4;                            /* Timer_A external input, SMCLK output */

        P1SEL |= BIT1 | BIT2;                           /* UART */
        P1SEL2 |= BIT1 | BIT2;

        TACTL = TASSEL_0 | MC_2 | TACLR;                /* External clock, continuous */

        p = 0;

        while(1)
        {
                n = TAR;
                TACTL |= TACLR;

                if(n != p)
                {
                        P1OUT |= BIT6;
                                                        /* Transmit in network byte order, BE */
                                                        /* receiver will ntohs() */
#if 1
                        UCA0TXBUF = (uint8_t)(n >> 8);  /* Transmit high byte; let USCI work */
                        while(UCA0STAT & UCBUSY)        /* Wait for high byte transmission */
                        {
                                ;
                        }
#endif
                        UCA0TXBUF = (uint8_t)(n);       /* Transmit low byte */
                }
                else
                {
                        P1OUT &= ~BIT6;
                }

                __delay_cycles(32);

                while(UCA0STAT & UCBUSY)                /* Wait for USCI to catch up, if it's still not done */
                {
                        ;
                }

                p = n;
        }
}