1.8.2 Analog-to-Digital Converter (ADC)

Using The Library

Interrupt mode:

#include <stddef.h>                     // Defines NULL
#include <stdbool.h>                    // Defines true
#include <stdlib.h>                     // Defines EXIT_FAILURE
#include "definitions.h"                // SYS function prototypes

#define ADC_VREF               (3.3f)

uint16_t adc_ch5_count, adc_ch6_count, adc_ch7_count;

float adc_ch5_voltage, adc_ch6_voltage, adc_ch7_voltage;

volatile bool result_ready = false;

/* This function is called after conversion of last channel in the user sequence */
void ADC_EventHandler(uint32_t interruptStatus, uint32_t eocInterruptStatus, uintptr_t context)
{
    /* Read the result of 3 channels*/
    adc_ch6_count = ADC_ChannelResultGet(ADC_CH6);
    adc_ch7_count = ADC_ChannelResultGet(ADC_CH7);
    adc_ch5_count = ADC_ChannelResultGet(ADC_CH5);
       
    result_ready = true;

}

// *****************************************************************************
// *****************************************************************************
// Section: Main Entry Point
// *****************************************************************************
// *****************************************************************************

int main ( void )
{
    /* Initialize all modules */
    SYS_Initialize ( NULL );
    
    /* Register callback function for ADC end of conversion interrupt*/
    ADC_CallbackRegister(ADC_EventHandler, (uintptr_t)NULL);
    
    printf("\n\r---------------------------------------------------------");
    printf("\n\r                    ADC User Sequence Demo                 ");
    printf("\n\r---------------------------------------------------------\n\r");
    printf("CH5 Count  CH5 Voltage  CH6 Count  CH6 Voltage  CH7 Count  CH7 Voltage \n\r");           

    TC0_CH0_CompareStart();

    while ( true )
    {
        /* Check if result is ready to be transmitted to console */
        if (result_ready == true)
        {
            adc_ch6_voltage = (float)adc_ch6_count * ADC_VREF/4095U;
            adc_ch7_voltage = (float)adc_ch7_count * ADC_VREF/4095U;
            adc_ch5_voltage = (float)adc_ch5_count * ADC_VREF/4095U;
            printf("0x%03x      %0.2f V       0x%03x      %0.2f V       0x%03x      %0.2f V \t\r",
                    adc_ch5_count, adc_ch5_voltage, adc_ch6_count, adc_ch6_voltage, adc_ch7_count, adc_ch7_voltage);
                           
                
            result_ready = false;
        }
    }

    /* Execution should not come here during normal operation */

    return ( EXIT_FAILURE );
}

Polling mode:

#include <stddef.h>                     // Defines NULL
#include <stdbool.h>                    // Defines true
#include <stdlib.h>                     // Defines EXIT_FAILURE
#include <stdio.h>
#include "definitions.h"                // SYS function prototypes

/*****************************************************
 ADC CH0 - PD19 - Connect to Vcc or GND
 *****************************************************/

#define ADC_VREF               (3.3f)

uint16_t adc_count;
float input_voltage;

// *****************************************************************************
// *****************************************************************************
// Section: Main Entry Point
// *****************************************************************************
// *****************************************************************************

int main ( void )
{
    /* Initialize all modules */
    SYS_Initialize ( NULL );
    
    printf("\n\r---------------------------------------------------------");
    printf("\n\r                    ADC Demo                 ");
    printf("\n\r---------------------------------------------------------\n\r");
    
    PIT64B0_TimerStart();

    while (1)
    {
        /* Start ADC conversion */
        ADC_ConversionStart();

        /* Wait till ADC conversion result is available */
        while(!ADC_ChannelResultIsReady(ADC_CH5))
        {

        };

        /* Read the ADC result */
        adc_count = ADC_ChannelResultGet(ADC_CH5);
        input_voltage = (float)adc_count * ADC_VREF / 4095U;

        printf("ADC Count = 0x%03x, ADC Input Voltage = %0.2f V \r",adc_count, input_voltage);    
        
        PIT64B0_DelayMs(500);
    }
    
    /* Execution should not come here during normal operation */

    return ( EXIT_FAILURE );
}

Library Interface

Analog-to-Digital Converter peripheral library provides the following interfaces:

Functions

Data types and constants