CCS/MSP432E401Y: Sampling in One Shot Mode: Distortion in Waveform

Part Number: MSP432E401Y

Tool/software: Code Composer Studio

Hello,

So I've got the MSP432's ADC Sampling a 20 kHz Sine Wave, but I always get a distortion for the first few samples (see figure below). I'm converting SampleBufferOne to MicroVolts and graphing it. (Sampling at 1 MSPS). I'm also curious as to what I need to do to sample this waveform at 2 MSPS. It somehow maxes out at 1 MSPS no matter what I set the sampling rate to.

Here's the code I have set up:

    /* Call ADC driver init function */
    ADCBuf_init();

    ADCBuf_Params_init(&adcBufParams);
    adcBufParams.recurrenceMode = ADCBuf_RECURRENCE_MODE_ONE_SHOT;
    adcBufParams.returnMode = ADCBuf_RETURN_MODE_BLOCKING;
    adcBufParams.samplingFrequency = 1000000;
    adcBufParams.blockingTimeout = 125000;
 
    adcBuf = ADCBuf_open(Board_ADCBUF0, &adcBufParams);

    if (adcBuf == NULL){
        /* ADCBuf failed to open. */
        while(1);
    }

    /* Configure the conversion struct */
    oneshotConversion.arg = NULL;
    oneshotConversion.adcChannel = Board_ADCBUF0CHANNEL0;
    oneshotConversion.sampleBuffer = sampleBufferOne;
    oneshotConversion.sampleBufferTwo = sampleBufferTwo;
    oneshotConversion.samplesRequestedCount = ADCSAMPLESIZE;

 /* Start converting. */
    if (ADCBuf_convert(adcBuf, &oneshotConversion, 1) !=
            ADCBuf_STATUS_SUCCESS) {
        /* Did not start conversion process correctly. */
        while(1);
    }

    // Normalize and convert to uVolts

    /* Adjust raw ADC values and convert them to microvolts */
    ADCBuf_adjustRawValues(adcBuf, oneshotConversion.sampleBuffer, ADCSAMPLESIZE,
                           Board_ADCBUF0CHANNEL0);
    ADCBuf_convertAdjustedToMicroVolts(adcBuf, Board_ADCBUF0CHANNEL0,
                                       oneshotConversion.sampleBuffer, microVoltBuffer, ADCSAMPLESIZE);

Here's my Signal: