1.38.2 Analog Digital Converter (ADC)

8-bit, 10-bit or 12-bit resolution
Up to 1,000,000 samples per second (1 MSPS)
Differential and single-ended inputs
Five internal inputs
Single, continuous, and sequencing options
Windowing monitor with selectable channel
Built-in internal reference and external reference options
Event-triggered conversion for accurate timing (one event input)
Optional DMA transfer of conversion settings or result
Hardware gain and offset compensation
Averaging and oversampling with decimation to support up to 16-bit result
Selectable sampling time
Flexible Power or Throughput rate management

Using The Library

ADC Sample:

#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

#define ADC_VREF                (3.3f)
#define DAC_COUNT_INCREMENT     (31U)  // equivalent to 0.1V(0.1 / (3.3 / ((2^10) - 1))) 
#define DAC_COUNT_MAX           (1023U)

uint16_t adc_count;
float input_voltage;
/* Initial value of dac count which is midpoint = 1.65 V*/
uint16_t dac_count = 0x200;   

void switch_handler(uintptr_t context )
{
    /* Write next data sample */
    dac_count = dac_count + DAC_COUNT_INCREMENT;
    
    if (dac_count > DAC_COUNT_MAX)
            dac_count=0;    
    
    DAC_DataWrite(dac_count);
}

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

int main ( void )
{
    /* Initialize all modules */
    SYS_Initialize ( NULL );
    
    printf("\n\r---------------------------------------------------------");
    printf("\n\r                    ADC Sample Demo                 ");
    printf("\n\r---------------------------------------------------------\n\r");
    
    ADC0_Enable();
    SYSTICK_TimerStart();
    EIC_CallbackRegister(EIC_PIN_3, switch_handler, (uintptr_t) NULL);
    DAC_DataWrite(dac_count);
    while (1)
    {
        /* Start ADC conversion */
        ADC0_ConversionStart();

        /* Wait till ADC conversion result is available */
        while(!ADC0_ConversionStatusGet())
        {

        };

        /* Read the ADC result */
        adc_count = ADC0_ConversionResultGet();
        input_voltage = (float)adc_count * ADC_VREF / 4095U;

        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));
        
        SYSTICK_DelayMs(500);
    }

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

    return ( EXIT_FAILURE );
}

Library Interface

Analog Digital Converter peripheral library provides the following interfaces:

Functions


Name	Description
ADCx_Initialize	Initializes given instance of ADC peripheral
ADCx_Enable	Enables given instance of ADC peripheral
ADCx_Disable	Disables given instance of ADC peripheral
ADCx_ChannelSelect	Selects ADC input channel
ADCx_ConversionStart	Starts the ADC conversion with the software trigger
ADCx_ConversionStatusGet	Returns the status of the conversion of the channel
ADCx_ConversionResultGet	Returns the conversion result of the channel
ADCx_ConversionSequenceIsFinished	Returns the status of automatic sequence conversion
ADCx_WindowMonitorStatusGet	Returns the status of the window monitor flag
ADCx_ComparisonWindowSet	Returns the status of automatic sequence conversion
ADCx_CallbackRegister	Registers the function to be called from interrupt

Data types and constants


Name	Type	Description
ADC_STATUS	Enum	Identifies ADC interrupt flag status
ADC_POSINPUT	Enum	Identifies ADC positive input pin to select
ADC_NEGINPUT	Enum	Identifies ADC negative input pin to select
ADC_CALLBACK	Typedef	Defines the data type and function signature for the ADC peripheral callback function