uart debugging example for the msp430 launchpad using usci

main.c

/*
 * Program that takes commands via Async Serial, which could be useful for debugging.
 * LEDs are green when transmitting data, and red when receiving data.
 *
 * G2553 Pinout:
 * 1.0 - red status led
 * 1.1 - uart input
 * 1.2 - uart output
 * 1.6 - green status led
 *
 * On the MSP-EXP430G2 Rev 1.5 board "J3" jumpers for RXD and TXD *must* be horizontal!!
 *
 * No crystal is needed for this program!
 */

#include "main.h"

int rxbytes = 0;  // total number of bytes received (view in debugger)
int txbytes = 0;  // total number of bytes sent (view in debugger)

void main()
{
    /* Clock Setup */
    WDTCTL = WDTPW + WDTHOLD;               // Stop WDT
    BCSCTL1 = CALBC1_1MHZ;                  // Run at 1 MHz
    DCOCTL = CALDCO_1MHZ;                   // Run at 1 MHz

    /* USCI Setup */
    P1SEL = BIT1 + BIT2;                    // Set pin modes to USCI_A0
    P1SEL2 = BIT1 + BIT2;                   // Set pin modes to USCI_A0
    P1DIR |= BIT2;                          // Set 1.2 to output
    UCA0CTL1 |= UCSSEL_2;                   // SMCLK
    UCA0BR0 = 104;                          // 1 MHz -> 9600
    UCA0BR1 = 0;                            // 1 MHz -> 9600
    UCA0MCTL = UCBRS1;                      // Modulation UCBRSx = 1
    UCA0CTL1 &= ~UCSWRST;                   // **Initialize USCI state machine**
    IE2 |= UCA0RXIE;                        // Enable USCI_A0 RX interrupt

    /* LED Setup */
    P1DIR |= (BIT0 | BIT6);
    P1OUT &= ~(BIT0 | BIT6);  // should be off already, but just be sure

    /* Main program */
    serial_log("Hello, master.  Enter a command:\r\n");
    __bis_SR_register(LPM0_bits + GIE);
}

/*
 * Send a log message to to the serial terminal
 */
inline void serial_log(const char *str)
{
    P1OUT |= BIT6;  // green led

    uint i;
    uint len = strlen(str);
    for (i = 0; i < len; i++) {
        // wait for TXBUF to complete last send...
        // UCA0TXIFG is high when UCA0TXBUF is empty
        while (!(IFG2 & UCA0TXIFG));
        UCA0TXBUF = str[i];
        txbytes++;
    }

    P1OUT &= ~BIT6;
}

#pragma vector=ADC10_VECTOR
__interrupt void ADC10_ISR()
{
    serial_log("Error!  Unhandled interrupt ADC10_ISR!\r\n");
}

#pragma vector=COMPARATORA_VECTOR
__interrupt void COMPARATORA_ISR()
{
    serial_log("Error!  Unhandled interrupt COMPARATORA_ISR!\r\n");
}

#pragma vector=NMI_VECTOR
__interrupt void NMI_ISR()
{
    serial_log("Error!  Unhandled interrupt NMI_ISR!\r\n");
}

#pragma vector=PORT1_VECTOR
__interrupt void PORT1_ISR()
{
    serial_log("Error!  Unhandled interrupt PORT1_ISR!\r\n");
}

#pragma vector=PORT2_VECTOR
__interrupt void PORT2_ISR()
{
    serial_log("Error!  Unhandled interrupt PORT2_ISR!\r\n");
}

#pragma vector=TIMER0_A0_VECTOR
__interrupt void TIMER0_A0_ISR()
{
    serial_log("Error!  Unhandled interrupt TIMER0_A0_ISR!\r\n");
}

#pragma vector=TIMER0_A1_VECTOR
__interrupt void TIMER0_A1_ISR()
{
    serial_log("Error!  Unhandled interrupt TIMER0_A1_ISR!\r\n");
}

#pragma vector=TIMER1_A0_VECTOR
__interrupt void TIMER1_A0_ISR()
{
    serial_log("Error!  Unhandled interrupt TIMER1_A0_ISR!\r\n");
}

#pragma vector=TIMER1_A1_VECTOR
__interrupt void TIMER1_A1_ISR()
{
    serial_log("Error!  Unhandled interrupt TIMER1_A1_ISR!\r\n");
}

/*
 * Accept a command entered on the serial terminal
 */
#pragma vector=USCIAB0RX_VECTOR
__interrupt void USCIAB0RX_ISR()
{

main.h

#ifndef MAIN_H
#define MAIN_H

/* System headers */
#include <msp430.h>
#include <string.h>

/*
 * Standard shortcuts preferred by humans
 */
typedef unsigned int uint;
#define TRUE 1
#define FALSE 0

// maximum length of a user-entered command
#define CMDLEN 12

/* Our global functions */
void serial_log(const char *str);

#endif /* MAIN_H */