CCS/MSP430FR5994: How to use ADC to measure voltage

Part Number:MSP430FR5994

Tool/software: Code Composer Studio

Here is a code that was in the FRAM utilities example that uses ADC to detect when power is lost

How do I modify this code to detect when the device drops down to a certain voltage

void initAdcMonitor(void)
{
    /* Initialize timer for ADC trigger. */
    TA0CCR0 = (SMCLK_FREQUENCY/ADC_MONITOR_FREQUENCY);
    TA0CCR1 = TA0CCR0/2;
    TA0CCTL1 = OUTMOD_3;
    TA0CTL = TASSEL__SMCLK | MC__UP;

    /* Configure internal 2.0V reference. */
    while(REFCTL0 & REFGENBUSY);
    REFCTL0 |= REFVSEL_1 | REFON;
    while(!(REFCTL0 & REFGENRDY));

    /*
     * Initialize ADC12_B window comparator using the battery monitor.
     * The monitor will first enable the high side to the monitor voltage plus
     * 0.1v to make sure the voltage is sufficiently above the threshold. When
     * the high side is triggered the interrupt service routine will switch to
     * the low side and wait for the voltage to drop below the threshold. When
     * the voltage drops below the threshold voltage the device will invoke the
     * compute through power loss shutdown function to save the application
     * state and enter complete device shutdown.
     */
    ADC12CTL0 = ADC12SHT0_2 | ADC12ON;
    ADC12CTL1 = ADC12SHS_1 | ADC12SSEL_0 | ADC12CONSEQ_2 | ADC12SHP;
    ADC12CTL3 = ADC12BATMAP;
    ADC12MCTL0 = ADC12INCH_31 | ADC12VRSEL_1 | ADC12WINC;
    ADC12HI = (uint16_t)(4096*((ADC_MONITOR_THRESHOLD+0.1)/2)/(2.0));
    ADC12LO = (uint16_t)(4096*(ADC_MONITOR_THRESHOLD/2)/(2.0));
    ADC12IFGR2 &= ~(ADC12HIIFG | ADC12LOIFG);
    ADC12IER2 = ADC12HIIE;
    ADC12CTL0 |= ADC12ENC;
}

#pragma vector = ADC12_VECTOR
__interrupt void ADC12_ISR(void)
{
    switch(__even_in_range(ADC12IV, ADC12IV_ADC12LOIFG)) {
        case ADC12IV_NONE:        break;        // Vector  0: No interrupt
        case ADC12IV_ADC12OVIFG:  break;        // Vector  2: ADC12MEMx Overflow
        case ADC12IV_ADC12TOVIFG: break;        // Vector  4: Conversion time overflow
        case ADC12IV_ADC12HIIFG:                // Vector  6: Window comparator high side
            /* Disable the high side and enable the low side interrupt. */
            ADC12IER2 &= ~ADC12HIIE;
            ADC12IER2 |= ADC12LOIE;
            ADC12IFGR2 &= ~ADC12LOIFG;
            break;
        case ADC12IV_ADC12LOIFG:                // Vector  8: Window comparator low side
            /* Enter device shutdown with 64ms timeout. */
            ctpl_enterShutdown(CTPL_SHUTDOWN_TIMEOUT_64_MS);

            /* Disable the low side and enable the high side interrupt. */
            ADC12IER2 &= ~ADC12LOIE;
            ADC12IER2 |= ADC12HIIE;
            ADC12IFGR2 &= ~ADC12HIIFG;
            break;
        default: break;
    }
}