Beginner
10 min

Achieve the perfect blend of safety and efficiency in your I2C communications with ISO1644 and ATmega2560

Put an end to signal interference and data loss

I2C Isolator 5 Click with Arduino Mega 2560 Rev3

Published Feb 14, 2024

Click board™

I2C Isolator 5 Click

Dev. board

Arduino Mega 2560 Rev3

Compiler

NECTO Studio

MCU

ATmega2560

Stop compromising between safety and efficiency - choose our I2C isolator to optimize your system's potential and safeguard your data.

A

A

Hardware Overview

How does it work?

I2C Isolator 5 Click is based on the ISO1644, a hot-swappable bidirectional I2C isolator with enhanced EMC and GPIOs from Texas Instruments. The ISO1644 bidirectionally buffers the two I2C signals across the isolation barrier while providing 5kVRMS of galvanic isolation. The isolation barrier consists of a double capacitive silicon dioxide and includes basic and reinforced insulation devices. In addition, the ISO1644 also integrates three unidirectional CMOS isolation channels with up to 50Mbps speed, which can be used for static GPIO signal isolation. It also integrates the logic required to support

bidirectional channels. The ISO1644 supports I2C 2-Wire bidirectional data transfer between a host device and several peripheral devices, where the host MCU controls the bus, specifically the serial clock (SCL) line. The data transfer can be made in standard, fast, fast-mode plus, and high-speed mode with speeds up to 3.4Mbps. As for three GPIO lines, the ISO1644 consists of two lines in one direction and one in the opposite direction. It could be used for any GPIO purpose. This Click board™ poses a terminal with isolated SCL and SDA lines. Besides, the terminal consists of VCC and GND lines and OUTA, OUTB, and INA, labeling

the direction of the lines. Those GPIO lines are connected to the mikroBUS™ socket, thus the host MCU, via OTA, OTB, and INA pins. If that suits your needs, you can pull up the isolated I2C lines via unpopulated R6 and R7 jumpers. 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. Also, this 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.

I2C Isolator 5 Click hardware overview image

Features overview

Development board

Arduino Mega 2560 is a robust microcontroller platform built around the ATmega 2560 chip. It has extensive capabilities and boasts 54 digital input/output pins, including 15 PWM outputs, 16 analog inputs, and 4 UARTs. With a 16MHz crystal

oscillator ensuring precise timing, it offers seamless connectivity via USB, a convenient power jack, an ICSP header, and a reset button. This all-inclusive board simplifies microcontroller projects; connect it to your computer via USB or power it up

using an AC-to-DC adapter or battery. Notably, the Mega 2560 maintains compatibility with a wide range of shields crafted for the Uno, Duemilanove, or Diecimila boards, ensuring versatility and ease of integration.

Arduino Mega 2560 Rev3 double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

AVR

MCU Memory (KB)

256

Silicon Vendor

Microchip

Pin count

100

RAM (Bytes)

8192

You complete me!

Accessories

Click Shield for Arduino Mega comes equipped with four mikroBUS™ sockets, with two in the form of a Shuttle connector, allowing all the Click board™ devices to be interfaced with the Arduino Mega board with no effort. Featuring an AVR 8-bit microcontroller with advanced RISC architecture, 54 digital I/O pins, and Arduino™ compatibility, the Arduino Mega board offers limitless possibilities for prototyping and creating diverse applications. This board is controlled and powered conveniently through a USB connection to program and debug the Arduino Mega board efficiently out of the box, with an additional USB cable connected to the USB B port on the board. Simplify your project development with the integrated ATmega16U2 programmer and unleash creativity using the extensive I/O options and expansion capabilities. There are eight switches, which you can use as inputs, and eight LEDs, which can be used as outputs of the MEGA2560. In addition, the shield features the MCP1501, a high-precision buffered voltage reference from Microchip. This reference is selected by default over the EXT REF jumper at the bottom of the board. You can choose an external one, as you would usually do with an Arduino Mega board. There is also a GND hook for testing purposes. Four additional LEDs are PWR, LED (standard pin D13), RX, and TX LEDs connected to UART1 (mikroBUS™ 1 socket). 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 Mega board with Click Shield for Arduino Mega, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.

Click Shield for Arduino Mega accessories 1 image

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
Output B Channel
PL1
RST
Chip Select
PL4
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
Output A Channel
PE4
PWM
Input A Channel
PB6
INT
NC
NC
TX
NC
NC
RX
I2C Clock
PD0
SCL
I2C Data
PD1
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

I2C Isolator 5 Click Schematic schematic

Step by step

Project assembly

Click Shield for Arduino Mega front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Arduino Mega 2560 Rev3 as your development board.

Click Shield for Arduino Mega front image hardware assembly
Arduino Mega 2560 Rev3 front image hardware assembly
Charger 27 Click front image hardware assembly
Prog-cut hardware assembly
Charger 27 Click complete accessories setup image hardware assembly
Arduino Mega 2560 Rev3 Access MB 1 - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
Necto image step 5 hardware assembly
Necto image step 6 hardware assembly
Arduino MEGA MCU Step hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Debug Image 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 I2C Isolator 5 Click driver.

Key functions:

  • i2cisolator5_set_slave_address - I2C Isolator 5 set I2C Slave address function.

  • i2cisolator5_set_outa_state - I2C Isolator 5 set output A state function.

  • i2cisolator5_get_ina_state - I2C Isolator 5 get input A state function.

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 I2C Isolator 5 Click example
 *
 * # Description
 * This library contains API for the I2C Isolator 5 click driver.
 * This demo application shows an example of an I2C Isolator 5 click 
 * wired to the VAV Press click for reading 
 * differential pressure and temperature measurement.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initialization of I2C module and log UART.
 * After driver initialization and default settings, 
 * the app set VAV Press click I2C slave address ( 0x5C ) 
 * and enable device.
 *
 * ## Application Task
 * This is an example that shows the use of an I2C Isolator 5 click board™.
 * Logs pressure difference [ Pa ] and temperature [ degree Celsius ] values 
 * of the VAV Press click written to the I2C Isolator 5 click board™.  
 * Results are being sent to the Usart Terminal where you can track their changes.
 *
 * @author Stefan Ilic
 *
 */

#include "board.h"
#include "log.h"
#include "i2cisolator5.h"

#define I2CISOLATOR5_VAV_PRESS_DEV_ADDR                             0x5C
#define I2CISOLATOR5_VAV_PRESS_CMD_START_PRESSURE_CONVERSION        0x21
#define I2CISOLATOR5_VAV_PRESS_PRESS_SCALE_FACTOR                   1200
#define I2CISOLATOR5_VAV_PRESS_TEMP_SCALE_FACTOR                    72
#define I2CISOLATOR5_VAV_PRESS_READOUT_AT_KNOWN_TEMPERATURE         105
#define I2CISOLATOR5_VAV_PRESS_KNOWN_TEMPERATURE_C                  23.1

static i2cisolator5_t i2cisolator5;
static log_t logger;
static float diff_press;
static float temperature;

/**
 * @brief I2C Isolator 5 get pressure difference and temperature function.
 * @details This function reads pressure difference and temperature from the VAV Press Click.
 * @return @li @c  0 - Success,
 *         @li @c -1 - Error.
 * See #err_t definition for detailed explanation.
 * @note None.
 */
err_t i2cisolator5_get_press_and_temp ( void );

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    i2cisolator5_cfg_t i2cisolator5_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.
    i2cisolator5_cfg_setup( &i2cisolator5_cfg );
    I2CISOLATOR5_MAP_MIKROBUS( i2cisolator5_cfg, MIKROBUS_1 );
    if ( I2C_MASTER_ERROR == i2cisolator5_init( &i2cisolator5, &i2cisolator5_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    log_printf( &logger, " Set VAV Press Click I2C Slave Address \r\n" );
    i2cisolator5_set_slave_address ( &i2cisolator5, I2CISOLATOR5_VAV_PRESS_DEV_ADDR );
    Delay_ms( 100 );
    
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
    if ( I2CISOLATOR5_OK == i2cisolator5_get_press_and_temp( ) )
    {
        log_printf( &logger, " Diff. Pressure : %.4f Pa \r\n", diff_press );
        log_printf( &logger, " Temperature : %.2f C \r\n", temperature );
        log_printf( &logger, "--------------------------------\r\n" );
    }
    
    Delay_ms( 2000 );
}

void main ( void ) 
{
    application_init( );

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

err_t i2cisolator5_get_press_and_temp ( void ) 
{
    err_t error_flag = I2CISOLATOR5_OK;
    uint8_t rx_buf[ 4 ] = { 0 };
    uint8_t tx_cmd = I2CISOLATOR5_VAV_PRESS_CMD_START_PRESSURE_CONVERSION;
    int16_t readout_data;
    
    error_flag |= i2cisolator5_write_then_read( &i2cisolator5, &tx_cmd, 1, rx_buf, 4 );
    
    if ( I2CISOLATOR5_OK == error_flag )
    {
        readout_data = rx_buf[ 1 ];
        readout_data <<= 8;
        readout_data |= rx_buf[ 0 ];
        readout_data <<= 1;
        readout_data >>= 1;
    
        diff_press = ( float ) readout_data;
        diff_press /= I2CISOLATOR5_VAV_PRESS_PRESS_SCALE_FACTOR;
   
        readout_data = rx_buf[ 3 ];
        readout_data <<= 8;
        readout_data |= rx_buf[ 2 ];
    
        temperature = ( float ) readout_data;
        temperature -= I2CISOLATOR5_VAV_PRESS_READOUT_AT_KNOWN_TEMPERATURE;
        temperature /= I2CISOLATOR5_VAV_PRESS_TEMP_SCALE_FACTOR;
        temperature += I2CISOLATOR5_VAV_PRESS_KNOWN_TEMPERATURE_C;
    }
    
    return error_flag;
}

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

Additional Support

Resources

Love this project?

'Buy This Kit' button takes you directly to the shopping cart where you can easily add or remove products.