Convert real-world physical quantities into digital data with AD7124-8 and ATmega328P

Eight-channel isolated sigma-delta ADC with PGA

Published Feb 14, 2024

Click board™

ISO ADC 6 Click

Dev.Board

Arduino UNO Rev3

Compiler

NECTO Studio

MCU

ATmega328P

High-precision analog-to-digital conversion with isolation capabilities suitable for various industrial and measurement applications

Hardware Overview

How does it work?

ISO ADC 6 Click is based on the AD7124-8, an 8-channel, low noise, low power, 24-bit, sigma-delta ADC, and the ADuM341E, a 5kVrms quad digital isolator, both from Analog Devices. The ADC incorporates a sigma-delta modulator, buffer, reference, gain stage, and on-chip digital filtering. It is intended to measure wide dynamic ranges, weigh scales, temperature measurement applications, and low-frequency signals. The ADC allows up to 16 configurations or channels consisting of analog inputs, reference inputs, or power supplies. All ADC channels are available over the A0-15 header, with a common GND, power supply, and a bridge power switch (PSW). You can add an external reference over the REF+ and REF-

pins. The internal reference has its output available over the REFOUT pin. The synchronization input is also available over the SNC pin. It allows synchronization of the digital filters and analog modulators when using several AD7124-8 devices. For this purpose, the internal clock is available over the CLK pin. Alternatively, the internal clock can be turned off, and this pin can provide an external clock, allowing simultaneous conversions. The isolator isolates the ADC communication lines to the host MCU. It features low propagation delay, low dynamic power consumption, 100Mbps maximum guaranteed data rate, and more. The isolator is based on CMOS, a monolithic air core transformer technology, and iCoupler technology.

ISO ADC 6 Click uses a standard 4-wire SPI serial interface of the ADC to communicate with the host MCU over the isolator barrier. The isolator uses a high-frequency carrier to transmit data across the isolation barrier using iCoupler chip scale transformer coils separated by layers of polyimide isolation. The ADC can work in three power modes, which allows sampling in a range of 1.17sps up to 19200sps. 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. Also, it comes equipped with a library containing functions and an example code that can be used as a reference for further development.

Features overview

Development board

Arduino UNO is a versatile microcontroller board built around the ATmega328P chip. It offers extensive connectivity options for various projects, featuring 14 digital input/output pins, six of which are PWM-capable, along with six analog inputs. Its core components include a 16MHz ceramic resonator, a USB connection, a power jack, an

ICSP header, and a reset button, providing everything necessary to power and program the board. The Uno is ready to go, whether connected to a computer via USB or powered by an AC-to-DC adapter or battery. As the first USB Arduino board, it serves as the benchmark for the Arduino platform, with "Uno" symbolizing its status as the

first in a series. This name choice, meaning "one" in Italian, commemorates the launch of Arduino Software (IDE) 1.0. Initially introduced alongside version 1.0 of the Arduino Software (IDE), the Uno has since become the foundational model for subsequent Arduino releases, embodying the platform's evolution.

Microcontroller Overview

MCU Card / MCU

Architecture

AVR

MCU Memory (KB)

Silicon Vendor

Microchip

Pin count

RAM (Bytes)

2048

You complete me!

Accessories

Click Shield for Arduino UNO has two proprietary mikroBUS™ sockets, allowing all the Click board™ devices to be interfaced with the Arduino UNO board without effort. The Arduino Uno, a microcontroller board based on the ATmega328P, provides an affordable and flexible way for users to try out new concepts and build prototypes with the ATmega328P microcontroller from various combinations of performance, power consumption, and features. The Arduino Uno has 14 digital input/output pins (of which six can be used as PWM outputs), six analog inputs, a 16 MHz ceramic resonator (CSTCE16M0V53-R0), a USB connection, a power jack, an ICSP header, and reset button. Most of the ATmega328P microcontroller pins are brought to the IO pins on the left and right edge of the board, which are then connected to two existing mikroBUS™ sockets. This Click Shield also has several switches that perform functions such as selecting the logic levels of analog signals on mikroBUS™ sockets and selecting logic voltage levels of the mikroBUS™ sockets themselves. Besides, the user is offered the possibility of using any Click board™ with the help of existing bidirectional level-shifting voltage translators, regardless of whether the Click board™ operates at a 3.3V or 5V logic voltage level. Once you connect the Arduino UNO board with our Click Shield for Arduino UNO, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.

Used MCU Pins

mikroBUS™ mapper

ID SEL

PD2

RST

SPI Select / ID COMM

PB2

SPI Clock

PB5

SCK

SPI Data OUT

PB4

MISO

SPI Data IN

PB3

MOSI

Power Supply

3.3V

Ground

GND

PWM

INT

SCL

SDA

Ground

GND

Take a closer look

Schematic

Step by step

Project assembly

Click Shield for Arduino UNO front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Arduino UNO Rev3 as your development board.

Arduino UNO Rev3 front image hardware assembly

Charger 27 Click front image hardware assembly

Charger 27 Click complete accessories setup image hardware assembly

Arduino UNO Rev3 Access MB 1 - upright/background hardware assembly

Necto No Display image step 8 hardware assembly

Debug Image Necto Step hardware assembly

Track your results in real time

Application Output

After loading the code example, pressing the "DEBUG" button builds and programs it on the selected setup.

After programming is completed, a header with buttons for various actions available in the IDE appears. By clicking the green "PLAY "button, we start reading the results achieved with Click board™.

Upon completion of programming, the Application Output tab is automatically opened, where the achieved result can be read. In case of an inability to perform the Debug function, check if a proper connection between the MCU used by the setup and the CODEGRIP programmer has been established. A detailed explanation of the CODEGRIP-board connection can be found in the CODEGRIP User Manual. Please find it in the RESOURCES section.

Software Support

Library Description

This library contains API for ISO ADC 6 Click driver.

Key functions:

isoadc6_get_voltage - ISO ADC 6 get voltage level function
isoadc6_get_adc_data - ISO ADC 6 get ADC data function
isoadc6_set_adc_control - ISO ADC 6 set ADC control function

Open Source

Code example

This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.

/*!
 * @file main.c
 * @brief ISO ADC 6 Click example
 *
 * # Description
 * This example demonstrates the use of the ISO ADC 6 Click board™ 
 * by reading and writing data by using SPI serial interface 
 * and reading results of AD conversion.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initialization of SPI module and log UART.
 * After driver initialization, the app executes a default configuration which enables channel 0,
 * puts A0 on positive analog input and A1 on negative analog input,
 * enables internal reference voltage (approximately 2.65V (AVDD = 3.3V)),
 * and also enables bipolar operation mode and puts device on full power mode.
 *
 * ## Application Task
 * The demo application reads the voltage levels from analog input (A0-A1) and displays the results.
 * Results are being sent to the UART Terminal, where you can track their changes.
 *
 * @author Mikroe Team
 *
 */

#include "board.h"
#include "log.h"
#include "isoadc6.h"

static isoadc6_t isoadc6;
static log_t logger;

void application_init ( void )
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    isoadc6_cfg_t isoadc6_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.
    isoadc6_cfg_setup( &isoadc6_cfg );
    ISOADC6_MAP_MIKROBUS( isoadc6_cfg, MIKROBUS_1 );
    if ( SPI_MASTER_ERROR == isoadc6_init( &isoadc6, &isoadc6_cfg ) )
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    if ( ISOADC6_ERROR == isoadc6_default_cfg ( &isoadc6 ) )
    {
        log_error( &logger, " Default configuration." );
        for ( ; ; );
    }
    
    log_info( &logger, " Application Task " );
}

void application_task ( void )
{
    float voltage = 0;
    if ( ISOADC6_OK == isoadc6_get_voltage( &isoadc6, &voltage ) )
    {
        log_printf( &logger, " Voltage: %.3f [V]\r\n", voltage );
        Delay_ms( 1000 );
    }
}

void main ( void )
{
    application_init( );

    for ( ; ; )
    {
        application_task( );
    }
}

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