MSP430FR5994: Connections needed for UART communication

#include <msp430.h>

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


    // Configure GPIO
    P6SEL1 &= ~(BIT0 | BIT1);
    P6SEL0 |= (BIT0 | BIT1);				// USCI_A3 UART operation

    // Disable the GPIO power-on default high-impedance mode to activate
    // previously configured port settings
    PM5CTL0 &= ~LOCKLPM5;

    // Startup clock system with max DCO setting ~8MHz
    CSCTL0_H = CSKEY_H;                     // Unlock CS registers
    CSCTL1 = DCOFSEL_3 | DCORSEL;           // Set DCO to 8MHz
    CSCTL2 = SELA__VLOCLK | SELS__DCOCLK | SELM__DCOCLK;
    CSCTL3 = DIVA__1 | DIVS__1 | DIVM__1;   // Set all dividers
    CSCTL0_H = 0;                           // Lock CS registers

    // Configure USCI_A3 for UART mode
    UCA3CTLW0 = UCSWRST;                    // Put eUSCI in reset
    UCA3CTLW0 |= UCSSEL__SMCLK;             // CLK = SMCLK
    // Baud Rate calculation
    // 8000000/(16*9600) = 52.083
    // Fractional portion = 0.083
    // User's Guide Table 21-4: UCBRSx = 0x04
    // UCBRFx = int ( (52.083-52)*16) = 1
    UCA3BRW = 52;                           // 8000000/16/9600
    UCA3MCTLW |= UCOS16 | UCBRF_1 | 0x4900;
    UCA3CTLW0 &= ~UCSWRST;                  // Initialize eUSCI
    UCA3IE |= UCRXIE;                       // Enable USCI_A3 RX interrupt

    __bis_SR_register(LPM3_bits | GIE);     // Enter LPM3, interrupts enabled
    __no_operation();                       // For debugger
}

#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=EUSCI_A3_VECTOR
__interrupt void USCI_A3_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(EUSCI_A3_VECTOR))) USCI_A3_ISR (void)
#else
#error Compiler not supported!
#endif
{
    switch(__even_in_range(UCA3IV, USCI_UART_UCTXCPTIFG))
    {
        case USCI_NONE: break;
        case USCI_UART_UCRXIFG:
            while(!(UCA3IFG&UCTXIFG));
            UCA3TXBUF = UCA3RXBUF;
            __no_operation();
            break;
        case USCI_UART_UCTXIFG: break;
        case USCI_UART_UCSTTIFG: break;
        case USCI_UART_UCTXCPTIFG: break;
        default: break;
    }
}