Convert analog signals into precise digital values with ADS1015L and ATmega1284

Delta-sigma (ΔΣ) 12-bit analog-to-digital converter with an I2C-compatible interface

Published Dec 18, 2024

Click board™

ADC 26 Click

Dev. board

EasyAVR v7

Compiler

NECTO Studio

MCU

ATmega1284

Low-power 12-bit analog-to-digital conversion for real-time performance in system monitoring and current sensing

Hardware Overview

How does it work?

ADC 26 Click is based on the ADS1015L, a low-power 12-bit analog-to-digital converter (ADC) with an I2C-compatible interface from Texas Instruments. It integrates several key components: a ΔΣ ADC core, an internal voltage reference, a clock oscillator, a programmable gain amplifier (PGA), and a programmable digital comparator. This combination enables the ADC to deliver conversions at data rates of up to 3300 samples per second (SPS), making it suitable for applications requiring both high speed and low noise. The ADC core of the ADS1015L measures differential signals brought to its analog input channels (IN0-IN3), offering a flexible full-scale input voltage range from ±0.256V to ±6.144V. This broad range enables the ADS1015L to handle both large and small signals with high precision, making it ideal for general system monitoring tasks such as supply voltage tracking, current sensing, and temperature measurements. These features also cater to applications in wearables and personal electronics. The IC's architecture comprises a differential switched-capacitor ΔΣ modulator followed by a digital filter, ensuring excellent attenuation of common-mode signals and high immunity to noise. The input signal is compared

against the internal voltage reference, while the modulator generates a high-speed bitstream. This stream is processed by the digital filter, which produces a digital output code proportional to the measured voltage. The ADS1015L supports two operational modes designed to optimize power consumption and performance based on application requirements. In single-shot mode, the ADC executes a single measurement upon request, stores the result in an internal register, and then enters a power-down state, making it particularly effective for systems that require periodic measurements or experience extended idle periods between conversions. In continuous-conversion mode, the ADC seamlessly initiates a new measurement as soon as the previous one is completed, maintaining a conversion rate consistent with the configured data rate. This mode is well-suited for real-time monitoring applications, as the data register consistently contains the most recent measurement. This Click board™ is designed in a unique format supporting the newly introduced MIKROE feature called "Click Snap." Unlike the standardized version of Click boards, this feature allows the main IC area to become movable by breaking the PCB, opening up many

new possibilities for implementation. Thanks to the Snap feature, the ADS1015l can operate autonomously by accessing its signals directly on the pins marked 1-8. Additionally, the Snap part includes a specified and fixed screw hole position, enabling users to secure the Snap board in their desired location. ADC 26 Click uses an I2C interface with clock speeds of up to 400kHz, ensuring fast and efficient communication with the host MCU. The I2C address can be easily configured via onboard ADDR SEL jumpers positioned in the Snap part of the board, allowing multiple devices to coexist on the same bus. Additionally, the board features an alert interrupt (AR) pin triggered whenever conversion data exceeds the limit set in the appropriate upper/lower threshold register, or it can be used as a conversion-ready pin. This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. It also comes equipped with a library containing functions and example code that can be used as a reference for further development.

Features overview

Development board

EasyAVR v7 is the seventh generation of AVR development boards specially designed for the needs of rapid development of embedded applications. It supports a wide range of 16-bit AVR microcontrollers from Microchip and has a broad set of unique functions, such as a powerful onboard mikroProg programmer and In-Circuit debugger over USB. The development board is well organized and designed so that the end-user has all the necessary elements in one place, such as switches, buttons, indicators, connectors, and others. With four different connectors for each port, EasyAVR v7 allows you to connect accessory boards, sensors, and custom electronics more

efficiently than ever. Each part of the EasyAVR v7 development board contains the components necessary for the most efficient operation of the same board. An integrated mikroProg, a fast USB 2.0 programmer with mikroICD hardware In-Circuit Debugger, offers many valuable programming/debugging options and seamless integration with the Mikroe software environment. Besides it also includes a clean and regulated power supply block for the development board. It can use a wide range of external power sources, including an external 12V power supply, 7-12V AC or 9-15V DC via DC connector/screw terminals, and a power source via the USB Type-B (USB-B)

connector. Communication options such as USB-UART and RS-232 are also included, alongside the well-established mikroBUS™ standard, three display options (7-segment, graphical, and character-based LCD), and several different DIP sockets which cover a wide range of 16-bit AVR MCUs. EasyAVR v7 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

Microcontroller Overview

MCU Card / MCU

Architecture

AVR

MCU Memory (KB)

128

Silicon Vendor

Microchip

Pin count

RAM (Bytes)

16384

Used MCU Pins

mikroBUS™ mapper

RST

ID COMM

PA5

SCK

MISO

MOSI

Power Supply

3.3V

Ground

GND

PWM

Comparator Output / Conversion Ready

PD2

INT

I2C Clock

PC0

SCL

I2C Data

PC1

SDA

Ground

GND

Take a closer look

Click board™ Schematic

Step by step

Project assembly

EasyAVR v7 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyAVR v7 as your development board.

NECTO Output Selection Step Image hardware assembly

In the advanced settings, pay special attention to the Redirect standard output field. By default, it is set to Application output as the method of displaying final results. To show results via a UART terminal, select the “UART” option in that field and click the “SAVE” button. You will be returned to the Compiler field, and now you can move on to the next step by pressing the “NEXT” button.

GNSS2 Click front image hardware assembly

GNSS2 Click complete accessories setup image hardware assembly

EasyAVR v7 Access DIP MB 1 - upright/background hardware assembly

NECTO Compiler Selection Step Image hardware assembly

Necto DIP image step 7 hardware assembly

EasyPIC PRO v7a Display Selection Necto Step hardware assembly

Track your results in real time

Application Output

This Click board can be interfaced and monitored in two ways:

Application Output - Use the "Application Output" window in Debug mode for real-time data monitoring. Set it up properly by following this tutorial.

UART Terminal - Monitor data via the UART Terminal using a USB to UART converter. For detailed instructions, check out this tutorial.

Software Support

Library Description

This library contains API for ADC 26 Click driver.

Key functions:

adc26_start_conversion - This function starts a single-shot conversion for the selected MUX channel and gain level (full-scale range).
adc26_get_alert_pin - This function returns the ALERT (data ready) pin logic state.
adc26_read_voltage - This function reads the RAW ADC measurement and converts it to a voltage level.

Open Source

Code example

The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.

/*!
 * @file main.c
 * @brief ADC 26 Click example
 *
 * # Description
 * This example demonstrates the use of ADC 26 click board by reading and
 * displaying the voltage levels from IN0-IN1 differential and IN2-IN3
 * single-ended analog input channels.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes the driver and performs the click default configuration.
 *
 * ## Application Task
 * Reads the voltage levels from IN0-IN1 differential (+/- 2.048V) and
 * IN2-IN3 single-ended (+/- 4.096V) analog input channels and displays
 * the results on the USB UART once per second approximately.
 *
 * @note
 * Do not apply more than VCC + 0.3 V to the analog inputs of the device.
 *
 * @author Stefan Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "adc26.h"

static adc26_t adc26;
static log_t logger;

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    adc26_cfg_t adc26_cfg;  /**< Click config object. */

    /** 
     * Logger initialization.
     * Default baud rate: 115200
     * Default log level: LOG_LEVEL_DEBUG
     * @note If USB_UART_RX and USB_UART_TX 
     * are defined as HAL_PIN_NC, you will 
     * need to define them manually for log to work. 
     * See @b LOG_MAP_USB_UART macro definition for detailed explanation.
     */
    LOG_MAP_USB_UART( log_cfg );
    log_init( &logger, &log_cfg );
    log_info( &logger, " Application Init " );

    // Click initialization.
    adc26_cfg_setup( &adc26_cfg );
    ADC26_MAP_MIKROBUS( adc26_cfg, MIKROBUS_1 );
    if ( I2C_MASTER_ERROR == adc26_init( &adc26, &adc26_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    if ( ADC26_ERROR == adc26_default_cfg ( &adc26 ) )
    {
        log_error( &logger, " Default configuration." );
        for ( ; ; );
    }
    
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
    float voltage = 0;
    if ( ADC26_OK == adc26_start_conversion ( &adc26, ADC26_MUX_P_AIN0_N_AIN1, ADC26_PGA_2_048V ) )
    {
        while ( adc26_get_alert_pin ( &adc26 ) ); // Waits for a data ready indication
        
        if ( ADC26_OK == adc26_read_voltage ( &adc26, &voltage ) )
        {
            log_printf ( &logger, " Voltage between IN0[P] and IN1[N]: %.3f V\r\n", voltage );
        }
    }
    if ( ADC26_OK == adc26_start_conversion ( &adc26, ADC26_MUX_P_AIN2_N_GND, ADC26_PGA_4_096V ) )
    {
        while ( adc26_get_alert_pin ( &adc26 ) ); // Waits for a data ready indication
        
        if ( ADC26_OK == adc26_read_voltage ( &adc26, &voltage ) )
        {
            log_printf ( &logger, " Voltage between IN2 and GND: %.3f V\r\n", voltage );
        }
    }
    if ( ADC26_OK == adc26_start_conversion ( &adc26, ADC26_MUX_P_AIN3_N_GND, ADC26_PGA_4_096V ) )
    {
        while ( adc26_get_alert_pin ( &adc26 ) ); // Waits for a data ready indication
        
        if ( ADC26_OK == adc26_read_voltage ( &adc26, &voltage ) )
        {
            log_printf ( &logger, " Voltage between IN3 and GND: %.3f V\r\n\n", voltage );
        }
    }
    Delay_ms ( 1000 );
}

int main ( void ) 
{
    /* Do not remove this line or clock might not be set correctly. */
    #ifdef PREINIT_SUPPORTED
    preinit();
    #endif
    
    application_init( );
    
    for ( ; ; ) 
    {
        application_task( );
    }

    return 0;
}

// ------------------------------------------------------------------------ END