adc10_a_ex6_refToggle.c

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 * Copyright (c) 2017, Texas Instruments Incorporated
 * All rights reserved.
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 * *  Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
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 *    its contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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#include "driverlib.h"
 
//******************************************************************************
//******************************************************************************
 
//Software delay function definition
void delay (void);
 
void main (void)
{
    uint8_t vRefStatus;
 
    //Stop Watchdog Timer
    WDT_A_hold(WDT_A_BASE);
 
    //Initialize the ADC10_A Module
    /*
     * Base Address for the ADC10_A Module
     * Use internal ADC10_A bit as sample/hold signal to start conversion
     * USE MODOSC 5MHZ Digital Oscillator as clock source
     * Use default clock divider of 1
     */
    ADC10_A_init(ADC10_A_BASE,
        ADC10_A_SAMPLEHOLDSOURCE_SC,
        ADC10_A_CLOCKSOURCE_ADC10OSC,
        ADC10_A_CLOCKDIVIDER_1);
 
    ADC10_A_enable(ADC10_A_BASE);
 
    /*
     * Base Address for the ADC10_A Module
     * Sample/hold for 16 clock cycles
     * Do not enable Multiple Sampling
     */
    ADC10_A_setupSamplingTimer(ADC10_A_BASE,
        ADC10_A_CYCLEHOLD_16_CYCLES,
        ADC10_A_MULTIPLESAMPLESDISABLE);
 
    //Configure Memory Buffer
    /*
     * Base Address for the ADC10_A Module
     * Use input A1
     * Use positive reference of Internally generated Vref
     * Use negative reference of AVss
     */
    ADC10_A_configureMemory(ADC10_A_BASE,
        ADC10_A_INPUT_A1,
        ADC10_A_VREFPOS_INT,
        ADC10_A_VREFNEG_AVSS);
 
    //Configure internal reference
    //If ref generator busy, WAIT
    while ( REF_BUSY == Ref_isRefGenBusy(REF_BASE) ) ;
    //Select internal ref = 1.5V
    Ref_setReferenceVoltage(REF_BASE,
        REF_VREF1_5V);
    //Internal Reference ON
    Ref_enableReferenceVoltage(REF_BASE);
    //vRefStatus == 1 for Vref == 1.5V
    vRefStatus = 1;
 
    //Delay (~75us) for Ref to settle
    __delay_cycles(75);
 
    //Set P1.0 to output direction
    GPIO_setAsOutputPin(GPIO_PORT_P1,
        GPIO_PIN0
        );
 
    //Clear P1.0 LED off
    GPIO_setOutputLowOnPin(GPIO_PORT_P1,
        GPIO_PIN0
        );
 
    while (1)
    {
        //Enable and Start the conversion
        //in Single-Channel, Single-Conversion Mode
        ADC10_A_startConversion(ADC10_A_BASE,
            ADC10_A_SINGLECHANNEL);
 
        //Toggle internal reference voltage
        //If ref generator busy, WAIT
        while ( REF_BUSY == Ref_isRefGenBusy(REF_BASE) ) ;
 
        //Toggle Internal Ref between 1.5V/2.5V
        if (vRefStatus){  //Vref == 1.5V
            //Select internal ref = 2.5V
            Ref_setReferenceVoltage(REF_BASE,
                REF_VREF2_5V);
            //vRefStatus == 0 for Vref == 2.5V
            vRefStatus = 0;
        } else   { //Vref == 2.5V
            //Select internal ref = 1.5V
            Ref_setReferenceVoltage(REF_BASE,
                REF_VREF1_5V);
            //vRefStatus == 1 for Vref == 1.5V
            vRefStatus = 1;
        }
 
        //Conversion complete?
        while (!(ADC10_A_getInterruptStatus(ADC10_A_BASE,
                     ADC10IFG0))) ;
 
        //Is ADC10MEM0 = A1 > 500
        if (ADC10_A_getResults(ADC10_A_BASE) > 500){
            //Set P1.0 LED on
            GPIO_setOutputHighOnPin(GPIO_PORT_P1,
                GPIO_PIN0
                );
        } else   {
            //Clear P1.0; LED off; Vref=2.5V used
            GPIO_setOutputLowOnPin(GPIO_PORT_P1,
                GPIO_PIN0
                );
        }
 
        //Delay between conversions
        delay();
    }
}
 
void delay (void)
{
    volatile uint32_t i;
 
    for (i = 0x7FFF; i > 0; i--){}
}