CCS/MSP430F5505: MSP430F5505 i2c master with MSP430G2553 slave BUSY failure

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

#define SLAVE_ADDR  0x48

#define MAX_BUFFER_SIZE     20

void initClockTo16MHz()
{
    if (CALBC1_16MHZ==0xFF)                  // If calibration constant erased
    {
        while(1);                               // do not load, trap CPU!!
    }
    DCOCTL = 0;                               // Select lowest DCOx and MODx settings
    BCSCTL1 = CALBC1_16MHZ;                    // Set DCO
    DCOCTL = CALDCO_16MHZ;
}

#define TIMERA_CCR0_BASE 2000

void timerA_init(void)
{
    //Set up Timer A register TACTL
    TACTL = 0x0000;     //start from all all clear
    TACTL |= BIT9;      //use SMCLK as the source
    TACTL |= BIT7;      //use prescaler 8
    TACTL |= BIT6;
    TACTL |= BIT4;      //count up to TACCR0(set below)
    TACTL |= BIT1;      //enable the interrupt
    TACTL &=~ BIT0;     //clear all pending interrupts
    TACCR0 = TIMERA_CCR0_BASE;      //use 2000 for 16 mhz
    TACCTL0 = CCIE;     //compare, capture interrupt enable
}

void initGPIO()
{
    P1DIR |= BIT4; // Set pin -> Output
    P1IE &= ~BIT4;   // Disable interrupts for pin

    P1DIR |= BIT5; // Set pin -> Output
    P1IE &= ~BIT5;   // Disable interrupts for pin

    P1SEL |= BIT6 + BIT7;                     // Assign I2C pins to USCI_B0
    P1SEL2|= BIT6 + BIT7;                     // Assign I2C pins to USCI_B0
}

void i2c_init()
{
    UCB0CTL1 |= UCSWRST;                      // Enable SW reset
    UCB0CTL0 = UCMODE_3 + UCSYNC;             // I2C Slave, synchronous mode
    UCB0I2COA = 0x48;                         // Own Address is 048h
    UCB0CTL1 &= ~UCSWRST;                     // Clear SW reset, resume operation
    UCB0I2CIE |= UCSTPIE + UCSTTIE;           // Enable STT and STP interrupt
    IE2 |= UCB0RXIE;                          // Enable RX interrupt
}


int main(void)
{
    WDTCTL = WDTPW | WDTHOLD;   // Stop watchdog timer

    initClockTo16MHz();

    initGPIO();

    timerA_init();

    i2c_init();

    __bis_SR_register(LPM0_bits + GIE);
    return 0;
}

typedef enum I2C_ModeEnum{
    IDLE_MODE,
    NACK_MODE,
    TX_REG_ADDRESS_MODE,
    RX_REG_ADDRESS_MODE,
    TX_DATA_MODE,
    RX_DATA_MODE,
    SWITCH_TO_RX_MODE,
    SWITHC_TO_TX_MODE,
    TIMEOUT_MODE
} I2C_Mode;

I2C_Mode SlaveMode = RX_REG_ADDRESS_MODE;

#pragma vector = USCIAB0TX_VECTOR
__interrupt void USCIAB0TX_ISR(void)
{
  P1OUT ^= BIT5;

  if (IFG2 & UCB0RXIFG)                 // Receive Data Interrupt
  {
      uint8_t rx_val = UCB0RXBUF;

      switch (SlaveMode)
      {
          case (RX_REG_ADDRESS_MODE):
              SlaveMode = RX_DATA_MODE;
              break;
          case (RX_DATA_MODE):
              SlaveMode = RX_REG_ADDRESS_MODE;
              //IE2 &= ~UCB0RXIE;                       // Disable RX interrupt
              //IE2 |= UCB0TXIE;                        // Enable TX interrupt
              break;
          default:
              _no_operation();
              break;
      }
  }
  else if (IFG2 & UCB0TXIFG)            // Transmit Data Interrupt
  {
      UCB0TXBUF = 0x02;

      SlaveMode = RX_REG_ADDRESS_MODE;

      //IE2 &= ~(UCB0TXIE);
      //IE2 |= UCB0RXIE;                          // Enable RX interrupt
  }
}

//------------------------------------------------------------------------------
// The USCI_B0 state ISR is used to wake up the CPU from LPM0 in order to do
// processing in the main program after data has been transmitted. LPM0 is
// only exit in case of a (re-)start or stop condition when actual data
// was transmitted.
//------------------------------------------------------------------------------
#pragma vector = USCIAB0RX_VECTOR
__interrupt void USCIAB0RX_ISR(void)
{
    P1OUT ^= BIT4;

    if (UCB0STAT & UCSTPIFG)                        //Stop or NACK Interrupt
    {
        UCB0STAT &=
            ~(UCSTTIFG + UCSTPIFG + UCNACKIFG);     //Clear START/STOP/NACK Flags
    }
    if (UCB0STAT & UCSTTIFG)
    {
        UCB0STAT &= ~(UCSTTIFG);                    //Clear START Flags
    }
}

#pragma vector = TIMER0_A0_VECTOR
__interrupt void Timer_A(void)
{
    //clear the timer interrupt
    TACTL &=~ BIT0;
}

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#include "MSP430F5xx_6xx/driverlib.h"

//*****************************************************************************
//! This example shows how to configure the I2C module as a master for
//! single byte transmission in interrupt mode. The address of the slave
//! module that the master is communicating with also set in this example.
//!
//! This example uses the following peripherals and I/O signals.  You must
//! review these and change as needed for your own board:
//! - I2C peripheral
//! - GPIO Port peripheral (for I2C pins)
//! - SCL2
//! - SDA
//!
//! This example uses the following interrupt handlers.  To use this example
//! in your own application you must add these interrupt handlers to your
//! vector table.
//! - USCI_B0_VECTOR.
//!
//
//*****************************************************************************
//*****************************************************************************
//
//Set the address for slave module. This is a 7-bit address sent in the
//following format:
//[A6:A5:A4:A3:A2:A1:A0:RS]
//
//A zero in the "RS" position of the first byte means that the master
//transmits (sends) data to the selected slave, and a one in this position
//means that the master receives data from the slave.
//
//*****************************************************************************
#define SLAVE_ADDRESS 0x48

uint8_t transmitData;

void i2c_send_byte(uint8_t txData)
{
    unsigned timeout = 1000;

    if(!USCI_B_I2C_isBusBusy(USCI_B0_BASE)) {
        //Send single byte data.
        USCI_B_I2C_masterSendSingleByteWithTimeout(USCI_B0_BASE,
            transmitData, timeout
         );
    }

    //Delay until transmission completes
    while (timeout--) {
        if(!USCI_B_I2C_isBusBusy(USCI_B0_BASE)) {
            break;
        }
    }
}

void main (void)
{
    //Stop WDT
    WDT_A_hold(WDT_A_BASE);

    GPIO_setAsOutputPin(
        GPIO_PORT_P4,
        GPIO_PIN7
    );

    //Assign I2C pins to USCI_B0
    GPIO_setAsPeripheralModuleFunctionInputPin(
        GPIO_PORT_P3,
        GPIO_PIN0 + GPIO_PIN1
        );

    //Initialize transmit data packet
    transmitData = 0x01;

    //Initialize Master
    USCI_B_I2C_initMasterParam param = {0};
    param.selectClockSource = USCI_B_I2C_CLOCKSOURCE_SMCLK;
    param.i2cClk = UCS_getSMCLK();
    param.dataRate = USCI_B_I2C_SET_DATA_RATE_400KBPS;
    USCI_B_I2C_initMaster(USCI_B0_BASE, &param);

    //Specify slave address
    USCI_B_I2C_setSlaveAddress(USCI_B0_BASE,
        SLAVE_ADDRESS
        );

    //Set in transmit mode
    USCI_B_I2C_setMode(USCI_B0_BASE,
        USCI_B_I2C_TRANSMIT_MODE
        );

    //Enable I2C Module to start operations
    USCI_B_I2C_enable(USCI_B0_BASE);

    //Enable TX interrupt
    USCI_B_I2C_clearInterrupt(USCI_B0_BASE,
        USCI_B_I2C_TRANSMIT_INTERRUPT
        );
    USCI_B_I2C_enableInterrupt(USCI_B0_BASE,
        USCI_B_I2C_TRANSMIT_INTERRUPT
        );

    while (1)
    {
        GPIO_toggleOutputOnPin(
                GPIO_PORT_P4,
                GPIO_PIN7
            );

        //Send single byte data.
        i2c_send_byte(
            transmitData
            );

        //Delay between each transaction
        __delay_cycles(50);

        //Increment transmit data counter
        transmitData++;
    }
}

//******************************************************************************
//
//This is the USCI_B0 interrupt vector service routine.
//
//******************************************************************************
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=USCI_B0_VECTOR
__interrupt
#elif defined(__GNUC__)
__attribute__((interrupt(USCI_B0_VECTOR)))
#endif
void USCI_B0_ISR (void)
{
    switch (__even_in_range(UCB0IV,12)){
        //Vector 12: Transmit buffer empty - TXIF
        case USCI_I2C_UCTXIFG:
        {
            __no_operation();
            break;
        }
        default:  break;
    }
}