MSP430 I2C USCI

// MSP430 - I2C TEST

// MCU = MSP430G2553

// COMPILE msp430-gcc -mmcu=msp430g2553 -o main.elf main.c

// Flash mspdebug rf2500 "prog main.elf"

#include <msp430.h>

// HARDWARE PINS on POT1

#define SCL   (BIT6)

#define SDA   (BIT7)

int  main()

{

  /* Init */

  /* Init DCO at 16MHZ */

  WDTCTL = WDTPW + WDTHOLD;

  BCSCTL1 = CALBC1_16MHZ;               // Set DCO

  DCOCTL = CALDCO_16MHZ;

  P1DIR |= SDA | SCL;

  //P1REN |= SDA | SCL;

  P1OUT = P1IN | SDA | SCL; 

  P1SEL|= SDA | SCL; // Assign UART and I2C Pins to USCI

  P1SEL2|= SDA | SCL;// Assign UART and I2C Pins to USCI

  /* USCI INIT */

  /* I2C INIT */

  UCB0CTL1 |= UCSWRST;

  UCB0CTL0 = UCMODE_3 + UCSYNC;// I2C Master, synchronous mode

  UCB0CTL1 = UCSSEL_2 + UCSWRST;// Use SMCLK, keep SW reset

  UCB0BR0 = 40;// fSCL = SMCLK/40 = ~400kHz

  UCB0BR1 = 0;

  UCB0I2COA = 0x11;

  UCB0CTL1 &= ~UCSWRST;// Clear SW reset

  /* USCI End Init */

  while(1)

  {

   // wait!!!

   int x =1000;

   while(x != 0){

      x--;

    }

    UCB0I2CSA = 0x50;

    UCB0CTL1 |= UCTR + UCTXSTT;

    while (!(IFG2 & UCB0TXIFG));

    UCB0TXBUF = 0x55;

    while (!(IFG2 & UCB0TXIFG));

    UCB0CTL1 |= UCTXSTP;

    while(UCB0CTL1 & UCTXSTP);

  }  

return 0;  

}