Convert your signals simultaneously using PCF8591 and ATmega644

ADC/DAC combo

Published Mar 06, 2023

Click board™

ADAC 3 Click

Dev. board

EasyAVR v7

Compiler

NECTO Studio

MCU

ATmega644

High-performance data acquisition solution

Hardware Overview

How does it work?

ADAC 3 Click is based on the PCF8591, a low-power CMOS data acquisition device from NXP Semiconductors. The PCF8591 comes with four analog inputs configurable as single-ended or differential inputs used to measure voltages, alongside one analog output representing an 8-bit digital-to-analog converter. In addition to measuring voltage, the user can create them as desired and even use DAC and ADC together to generate an input to a circuit and measure the results with the ADC, making it suitable for various control, monitoring, or measurement applications. By its internal structure, the PCF8591 also consists of

an analog input multiplexing circuit and an on-chip track and hold function alongside a serial interface block. This Click board™ communicates with MCU using the standard I2C 2-Wire interface with a maximum clock frequency of 100kHz. The PCF8591 has a 7-bit slave address with the first four MSBs fixed to 1001. The address pins A0, A1, and A2 are programmed by the user and determine the value of the last three LSBs of the slave address, which can be selected by positioning onboard SMD jumpers labeled as ADDR SEL to an appropriate position marked as 0 or 1. Besides, the user can choose the PCF8591

reference voltage value by positioning the SMD jumper labeled VREF SEL, choosing between 2,048 and 4,096V provided by MAX6104 and MAX6106. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. However, the Click board™ comes equipped with a library containing easy-to-use functions and an 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)

Silicon Vendor

Microchip

Pin count

RAM (Bytes)

4096

Used MCU Pins

mikroBUS™ mapper

RST

SCK

MISO

MOSI

Power Supply

3.3V

Ground

GND

PWM

INT

I2C Clock

PC0

SCL

I2C Data

PC1

SDA

Power Supply

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

1. Application Output - In Debug mode, the 'Application Output' window enables real-time data monitoring, offering direct insight into execution results. Ensure proper data display by configuring the environment correctly using the provided tutorial.

2. UART Terminal - Use the UART Terminal to monitor data transmission via a USB to UART converter, allowing direct communication between the Click board™ and your development system. Configure the baud rate and other serial settings according to your project's requirements to ensure proper functionality. For step-by-step setup instructions, refer to the provided tutorial.

3. Plot Output - The Plot feature offers a powerful way to visualize real-time sensor data, enabling trend analysis, debugging, and comparison of multiple data points. To set it up correctly, follow the provided tutorial, which includes a step-by-step example of using the Plot feature to display Click board™ readings. To use the Plot feature in your code, use the function: plot(*insert_graph_name*, variable_name);. This is a general format, and it is up to the user to replace 'insert_graph_name' with the actual graph name and 'variable_name' with the parameter to be displayed.

Software Support

Library Description

This library contains API for ADAC 3 Click driver.

Key functions:

adac3_write_control This function writes a control byte by using I2C serial interface.
adac3_write_dac This function writes a DAC byte by using I2C serial interface.
adac3_read_adc This function reads the AD conversion byte by using I2C serial interface.

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 ADAC3 Click example
 *
 * # Description
 * This example demonstrates the use of ADAC 3 Click board by setting the DAC output
 * and reading the ADC results from 2 single-ended channels (AIN0, AIN1) and from a 
 * differential channel (AIN2+, AIN3-).
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes the driver and performs the Click default configuration which enables
 * DAC output, sets the analog input mode to single-ended (AIN0, AIN1) and 
 * differential (AIN2+, AIN3-), and enables the auto increment mode.
 *
 * ## Application Task
 * Sets the DAC output increasing the value by 1 after each iteration, and reads the 
 * ADC results from 2 single-ended and 1 differential channels, and displays the results
 * on the USB UART every 100ms approximately.
 *
 * @note
 * Inputs should be connected to GND when not in use.
 *
 * @author Stefan Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "adac3.h"

static adac3_t adac3;
static log_t logger;

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    adac3_cfg_t adac3_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.
    adac3_cfg_setup( &adac3_cfg );
    ADAC3_MAP_MIKROBUS( adac3_cfg, MIKROBUS_1 );
    if ( I2C_MASTER_ERROR == adac3_init( &adac3, &adac3_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    if ( ADAC3_ERROR == adac3_default_cfg ( &adac3 ) )
    {
        log_error( &logger, " Default configuration." );
        for ( ; ; );
    }
    
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
    static uint8_t dac = 0;
    uint8_t ain0, ain1, ain2_ain3_diff;
    if ( ADAC3_OK == adac3_write_dac ( &adac3, dac ) )
    {
        log_printf ( &logger, " DAC : %u mV\r\n", 
                     ( uint16_t ) ( ( ADAC3_VREF_2048mV / ADAC3_RESOLUTION ) * dac++ ) );
    }
    if ( ADAC3_OK == adac3_read_adc ( &adac3, &ain0 ) )
    {
        log_printf ( &logger, " AIN0+: %u mV\r\n", 
                     ( uint16_t ) ( ( ADAC3_VREF_2048mV / ADAC3_RESOLUTION ) * ain0 ) );
    }
    if ( ADAC3_OK == adac3_read_adc ( &adac3, &ain1 ) )
    {
        log_printf ( &logger, " AIN1+: %u mV\r\n",
                     ( uint16_t ) ( ( ADAC3_VREF_2048mV / ADAC3_RESOLUTION ) * ain1 ) );
    }
    if ( ADAC3_OK == adac3_read_adc ( &adac3, &ain2_ain3_diff ) )
    {
        log_printf ( &logger, " AIN2+ - AIN3-: %d mV\r\n\n",
                     ( int16_t ) ( ( ADAC3_VREF_2048mV / ADAC3_RESOLUTION ) * ( int8_t ) ain2_ain3_diff ) );
    }
    Delay_ms ( 100 );
}

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