MSP432 ADC input buffer

/*
 * -------------------------------------------
 *    MSP432 DriverLib - v3_21_00_05 
 * -------------------------------------------
 *
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 * Copyright (c) 2016, Texas Instruments Incorporated
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/*******************************************************************************
 * MSP432 ADC14 - Single Channel Sample Repeat
 *
 * Description: This code example will demonstrate the basic functionality of
 * of the DriverLib ADC APIs with sampling a single channel repeatedly. Each
 * time the ADC conversion occurs, the result is stored into a local variable.
 * The sample timer is used to continuously grab a new value from the ADC
 * module using a manual iteration that is performed in the ADC ISR. A
 * normalized ADC value with respect to the 3.3v Avcc is also calculated using
 * the FPU.
 *
 *                MSP432P401
 *             ------------------
 *         /|\|                  |
 *          | |                  |
 *          --|RST         P5.5  |<--- A0 (Analog Input)
 *            |                  |
 *            |                  |
 *            |                  |
 *            |                  |
 *            |                  |
 *
 * Author: Timothy Logan
 ******************************************************************************/
/* DriverLib Includes */
#include "driverlib.h"

/* Standard Includes */
#include <stdint.h>

#include <stdbool.h>

/* Statics */
static volatile uint16_t curADCResult;
static volatile float normalizedADCRes;

int main(void)
{
    /* Halting the Watchdog  */
    MAP_WDT_A_holdTimer();

    /* Initializing Variables */
    curADCResult = 0;

    /* Setting Flash wait state */
    MAP_FlashCtl_setWaitState(FLASH_BANK0, 2);
    MAP_FlashCtl_setWaitState(FLASH_BANK1, 2);
    
    /* Setting DCO to 48MHz  */
    MAP_PCM_setPowerState(PCM_AM_LDO_VCORE1);
    MAP_CS_setDCOCenteredFrequency(CS_DCO_FREQUENCY_48);

    /* Enabling the FPU for floating point operation */
    MAP_FPU_enableModule();
    MAP_FPU_enableLazyStacking();

    /* Initializing ADC (MCLK/1/4) */
    MAP_ADC14_enableModule();
    MAP_ADC14_initModule(ADC_CLOCKSOURCE_MCLK, ADC_PREDIVIDER_1, ADC_DIVIDER_4,
            0);
            
    /* Configuring GPIOs (5.5 A0) */
    MAP_GPIO_setAsPeripheralModuleFunctionInputPin(GPIO_PORT_P5, GPIO_PIN5,
    GPIO_TERTIARY_MODULE_FUNCTION);

    /* Configuring ADC Memory */
    MAP_ADC14_configureSingleSampleMode(ADC_MEM0, true);
    MAP_ADC14_configureConversionMemory(ADC_MEM0, ADC_VREFPOS_INTBUF_VREFNEG_VSS,
    ADC_INPUT_A0, false);

    /* Setting reference voltage to 2.5 and enabling temperature sensor */
    REF_A_setReferenceVoltage(REF_A_VREF2_5V);
    REF_A_enableReferenceVoltage();


    /* Configuring Sample Timer */
    MAP_ADC14_enableSampleTimer(ADC_MANUAL_ITERATION);

    /* Enabling/Toggling Conversion */
    MAP_ADC14_enableConversion();
    MAP_ADC14_toggleConversionTrigger();

    /* Enabling interrupts */
    MAP_ADC14_enableInterrupt(ADC_INT0);
    MAP_Interrupt_enableInterrupt(INT_ADC14);
    MAP_Interrupt_enableMaster();

    while (1)
    {
        MAP_PCM_gotoLPM0();
    }
    
}

/* ADC Interrupt Handler. This handler is called whenever there is a conversion
 * that is finished for ADC_MEM0.
 */
void ADC14_IRQHandler(void)
{
    uint64_t status = MAP_ADC14_getEnabledInterruptStatus();
    MAP_ADC14_clearInterruptFlag(status);

    if (ADC_INT0 & status)
    {
        curADCResult = MAP_ADC14_getResult(ADC_MEM0);
        normalizedADCRes = (curADCResult * 2.5) / 16384;

        																																									MAP_ADC14_toggleConversionTrigger();
    }
}