2.4 Analog to Digital Converter (ADCHS)

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)
#define ADC_MAX_COUNT           (4095)

uint16_t adc_count;
float input_voltage;
volatile bool result_ready = false;

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

void ADC_ResultHandler(ADCHS_CHANNEL_NUM channel, uintptr_t context)
{
    /* Read the ADC result */
    adc_count = ADCHS_ChannelResultGet(ADCHS_CH3);    
    result_ready = true;
}


int main ( void )
{
    /* Initialize all modules */
    SYS_Initialize ( NULL );
    
    printf("\n\r---------------------------------------------------------");
    printf("\n\r                    ADC Interrupt Mode Demo                 ");
    printf("\n\r---------------------------------------------------------\n\r"); 
    
    ADCHS_CallbackRegister(ADCHS_CH3, ADC_ResultHandler, (uintptr_t)NULL);
    TMR3_Start();
    
    while ( true )
    {
        /* Maintain state machines of all polled MPLAB Harmony modules. */
        SYS_Tasks ( );
        
        /* Wait till ADC conversion result is available */
        if (result_ready == true)
        {
            result_ready = false;
            input_voltage = (float)adc_count * ADC_VREF / ADC_MAX_COUNT;

            printf("ADC Count = 0x%03x, ADC Input Voltage = %d.%02d V \r", adc_count, (int)input_voltage, (int)((input_voltage - (int)input_voltage)*100.0));        
        }
    }

    /* 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 "definitions.h"                // SYS function prototypes

#define ADC_VREF                (3.3f)
#define ADC_MAX_COUNT           (4095)

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 Polled Mode Demo                 ");
    printf("\n\r---------------------------------------------------------\n\r"); 
    
    TMR3_Start();
    
    while ( true )
    {
        /* Maintain state machines of all polled MPLAB Harmony modules. */
        SYS_Tasks ( );
        
        /* Wait till ADC conversion result is available */
        while(!ADCHS_ChannelResultIsReady(ADCHS_CH3))
        {

        };

        /* Read the ADC result */
        adc_count = ADCHS_ChannelResultGet(ADCHS_CH3);
        input_voltage = (float)adc_count * ADC_VREF / ADC_MAX_COUNT;

        printf("ADC Count = 0x%03x, ADC Input Voltage = %d.%02d V \r", adc_count, (int)input_voltage, (int)((input_voltage - (int)input_voltage)*100.0));        
    }

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

    return ( EXIT_FAILURE );
}

Library Interface

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

Functions

Data types and constants