MSP430G2553: I2C not sending the acknowledge clock cycle

Tool/software:

Hi,

I'm currently trying to write a code that reads and writes to the APDS-9900, it's a device that measures the distance between sensor and objects. With my current code i try to preform a simple read operation that reads the ID of the chip just to if the I2C works, that is address 0x12 and i expect value 0x29 back.

But when i try to run it keeps stuck on the while (UCB0CTL1 & UCTXSTT); and locking through my osciloscoop it seems the last acknowedge clock is not send.

Any idea on how to fix that or what am i doing wrong?

Under the code functions that i use to read byte and word.

#include <Header/i2c.h>

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

void I2C_Init(void) {
    // Set P1.6 and P1.7 as I2C pins
    P1SEL |= BIT6 + BIT7;
    P1SEL2 |= BIT6 + BIT7;

    // Set up USCI_B0 for I2C master mode
    UCB0CTL1 |= UCSWRST;                      // Enable software reset
    UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC;     // I2C master mode, synchronous mode
    UCB0CTL1 = UCSSEL_2 + UCSWRST;            // Use SMCLK, keep reset
    UCB0BR0 = 12;                             // Set bit rate (assuming 1MHz SMCLK, 100kHz I2C)
    UCB0BR1 = 0;
    UCB0CTL1 &= ~UCSWRST;                     // Clear reset to enable I2C
    IFG2 &= ~(UCB0RXIFG + UCB0TXIFG); // Clear flags
    IE2 |= UCB0RXIE + UCB0TXIE;               // Enable RX and TX interrupts
}

unsigned char I2C_Read_Combined(unsigned char regAddr) {

    UCB0I2CSA = 0x39;                         // Set APDS-9900 I2C address
    UCB0CTL1 |= UCTR + UCTXSTT;               // Set as transmitter, generate START condition
    while (UCB0CTL1 & UCTXSTT);               // Wait for START condition to complete
    UCB0TXBUF = regAddr;                      // Send register address
    while (!(IFG2 & UCB0TXIFG));              // Wait for transmission to complete
    UCB0CTL1 &= ~UCTR;                        // Set as receiver
    UCB0CTL1 |= UCTXSTT;                      // Generate repeated START condition
    while (UCB0CTL1 & UCTXSTT);               // Wait for START condition to complete
    UCB0CTL1 |= UCTXSTP;                      // Generate STOP after next byte
    while (!(IFG2 & UCB0RXIFG));              // Wait for data to be received
    return UCB0RXBUF;                         // Return received data
}


unsigned int I2C_Read_Word(unsigned char regAddr) {
    unsigned int data = 0;
    UCB0I2CSA = 0x39;                         // Set APDS-9900 I2C address
    UCB0CTL1 |= UCTR + UCTXSTT;               // Set as transmitter, generate START
    while (UCB0CTL1 & UCTXSTT);               // Wait for START to complete
    UCB0TXBUF = regAddr;                      // Send register address
    while (!(IFG2 & UCB0TXIFG));              // Wait for transmission to complete
    UCB0CTL1 &= ~UCTR;                        // Set as receiver
    UCB0CTL1 |= UCTXSTT;                      // Generate repeated START
    while (UCB0CTL1 & UCTXSTT);               // Wait for START to complete
    data = UCB0RXBUF;                         // Read first byte
    data <<= 8;                               // Shift to high byte
    while (!(IFG2 & UCB0RXIFG));              // Wait for second byte
    data |= UCB0RXBUF;                        // Read second byte
    UCB0CTL1 |= UCTXSTP;                      // Generate STOP
    return data;
}

How the datasheet says the I2C protocol must work in order to comunicate with the APDS-9900.

My results using my osciloscoop. blue is SDA and yellow is SCL.

The last clock signal is not send as you can see.