Experience uninterrupted I2C communication across extended distances with PCA9615 and ATmega2560

Expand, Connect, Thrive: Your I2C bus extension solution!

I2C Extend 2 Click with Arduino Mega 2560 Rev3

Published Feb 14, 2024

Click board™

I2C Extend 2 Click

Dev Board

Arduino Mega 2560 Rev3

Compiler

NECTO Studio

MCU

ATmega2560

Expand the possibilities of your I2C-enabled projects with ease, thanks to our bus extension solution, designed to simplify the integration of remote sensors, displays, and control devices

Hardware Overview

How does it work?

I2C Extend 2 Click is based on the PCA9615, a Fast-Mode Plus (FM+) I2C bus buffer that extends the single-ended I2C bus through electrically noisy environments from NXP Semiconductor. It consists of two single-ended to differential driver channels for the SCL (Serial Clock) and SDA (Serial Data). Differential transmission lines between identical I2C bus buffers remove electrical noise and common-mode offsets when signals pass between different voltage domains, such as high-energy power supplies and electric motors. Those signals can reach up to 3m or longer at lower clock speeds while maintaining signal integrity sent over an Ethernet cable (a twisted-pair transmission line cable) through the onboard RJ-45 connector. The PCA9615 converts the default I2C signals into four differential signals, two for SCL and two for SDA. The signal direction is

determined by the I2C protocol, which means it does not require a direction signal, as these bus buffers automatically set signal flow direction. Additional circuitry allows the PCA9615 to be used for ‘hot-swap’ applications, where systems are always ON but require insertion or removal of modules or cards without disrupting existing signals. Because the supply voltages on the I2C bus side may differ from the external I2C bus side, there are two power supply pins and common ground. The first is a standard I2C bus-side power supply selected via the VCC SEL jumper, and the other represents the majority supply for circuitry determined by the VDD SEL jumper. I2C Extend 2 Click communicates with MCU using the standard I2C interface with a frequency of up to 100kHz in the Standard 400kHz in the Fast Mode and up to 1MHz in the Fast Mode Plus. The user must be

cautious not to overload the driver's current rating of 3mA for Standard and Fast Modes and 30mA for Fast Mode Plus (FM+). Also, this Click board™ has an Enable pin, routed on the CS pin of the mikroBUS™ socket labeled as EN, used to turn off the bus buffer, and is useful for fault finding, Power-Up sequencing, or re-configuration of a bus system by isolating sections not needed at all times. 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.

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

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.

Used MCU Pins

mikroBUS™ mapper

RST

Enable

PL4

SCK

MISO

MOSI

Power Supply

3.3V

Ground

GND

PWM

INT

I2C Clock

PD0

SCL

I2C Data

PD1

SDA

Power Supply

Ground

GND

Take a closer look

Click board™ 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.

Arduino Mega 2560 Rev3 front image hardware assembly

Charger 27 Click front image hardware assembly

Charger 27 Click complete accessories setup image hardware assembly

Arduino Mega 2560 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

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 Extend 2 Click driver.

Key functions:

i2cextend2_rmt_write - Generic write data in Remote Mode function
i2cextend2_rmt_read - Generic read data in Remote Mode function
i2cextend2_enable - Enable extend 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 I2CExtend2 Click example
 *
 * # Description
 * This is an example which demonstrates the use of I2C Extend 2 Click board.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initialization driver enables - I2C,
 * check communication with device 6DOF IMU 11 Click
 * connected to the I2C Extend 2 Click ( Remote Mode ),
 * set default configuration and start measurement.
 *
 * ## Application Task
 * In this example, we read Accel and Mag axis of the connected
 * 6DOF IMU 11 Click boards to the I2C Extend 2 Click ( Remote Mode )
 * which is connected by a LAN cable to I2C Extend 2 Click ( Local Mode ).
 * Results are being sent to the Usart Terminal where you can track their changes.
 * All data logs write on USB uart changes for every 2 sec.
 *
 * @author Stefan Ilic
 *
 */

#include "board.h"
#include "log.h"
#include "i2cextend2.h"

static i2cextend2_t i2cextend2;
static log_t logger;
int16_t axis;

void i2cextend2_6dofimu11_get_axis ( i2cextend2_t *ctx, uint8_t axis_out_reg ) 
{
    uint16_t rx_val = 0;

    rx_val = i2cextend2_rmt_read( ctx, axis_out_reg + 1 );
    rx_val <<= 8;
    rx_val |= i2cextend2_rmt_read( ctx, axis_out_reg );

    axis = ( int16_t ) rx_val;
}

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    i2cextend2_cfg_t i2cextend2_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.
    i2cextend2_cfg_setup( &i2cextend2_cfg );
    I2CEXTEND2_MAP_MIKROBUS( i2cextend2_cfg, MIKROBUS_1 );
    if ( I2C_MASTER_ERROR == i2cextend2_init( &i2cextend2, &i2cextend2_cfg ) ) 
    {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );
        for ( ; ; );
    }

    i2cextend2_enable( &i2cextend2, I2CEXTEND2_EXTEND_ENABLE );

    if ( C6DOFIMU11_WHO_AM_I_WIA_ID == i2cextend2_rmt_read( &i2cextend2, C6DOFIMU11_REG_WHO_AM_I ) ) 
    {
        log_printf( &logger, "        SUCCESS         \r\n" );
        log_printf( &logger, "------------------------\r\n" );
    } 
    else 
    {
        log_printf( &logger, "         ERROR          \r\n" );
        log_printf( &logger, "    Reset the device    \r\n" );
        log_printf( &logger, "------------------------\r\n" );
        for ( ; ; );
    }
    i2cextend2_rmt_write ( &i2cextend2, C6DOFIMU11_REG_CNTL2, C6DOFIMU11_CNTL2_TEMP_EN_STANDBY_MODE |
                                                              C6DOFIMU11_CNTL2_MAG_EN_STANDBY_MODE |
                                                              C6DOFIMU11_CNTL2_ACCEL_EN_STANDBY_MODE );

    i2cextend2_rmt_write ( &i2cextend2, C6DOFIMU11_REG_INC3, C6DOFIMU11_INC3_IEL2_FIFO_TRIG |
                                                             C6DOFIMU11_INC3_IEL1_FIFO_TRIG );

    i2cextend2_rmt_write ( &i2cextend2, C6DOFIMU11_REG_CNTL2, C6DOFIMU11_CNTL2_GSEL_8G |
                                                              C6DOFIMU11_CNTL2_RES_MAX2 |
                                                              C6DOFIMU11_CNTL2_MAG_EN_OPERATING_MODE |
                                                              C6DOFIMU11_CNTL2_ACCEL_EN_OPERATING_MODE );
    Delay_ms ( 100 );
    log_info( &logger, " Application Task " );
    log_printf( &logger, "------------------------\r\n" );
}

void application_task ( void ) 
{
    log_printf( &logger, "\t   Accel   \t|\t    Mag    \r\n" );
    log_printf( &logger, "------------------------------------------------\r\n" );

    i2cextend2_6dofimu11_get_axis( &i2cextend2, C6DOFIMU11_REG_ACCEL_XOUT_L );
    log_printf( &logger, "\t Accel X: %d\t|", axis );
    i2cextend2_6dofimu11_get_axis( &i2cextend2, C6DOFIMU11_REG_MAG_XOUT_L );
    log_printf( &logger, "\t Mag X: %d\r\n", axis );

    i2cextend2_6dofimu11_get_axis( &i2cextend2, C6DOFIMU11_REG_ACCEL_YOUT_L );
    log_printf( &logger, "\t Accel Y: %d\t|", axis );
    i2cextend2_6dofimu11_get_axis( &i2cextend2, C6DOFIMU11_REG_MAG_YOUT_L );
    log_printf( &logger, "\t Mag Y: %d\r\n", axis );

    i2cextend2_6dofimu11_get_axis( &i2cextend2, C6DOFIMU11_REG_ACCEL_ZOUT_L );
    log_printf( &logger, "\t Accel Z: %d\t|", axis );
    i2cextend2_6dofimu11_get_axis( &i2cextend2, C6DOFIMU11_REG_MAG_ZOUT_L );
    log_printf( &logger, "\t Mag Z: %d\r\n", axis );

    log_printf( &logger, "------------------------------------------------\r\n" );
    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

/*!
 * @file main.c
 * @brief I2CExtend2 Click example
 *
 * # Description
 * This is an example which demonstrates the use of I2C Extend 2 Click board.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initialization driver enables - I2C,
 * check communication with device 6DOF IMU 11 Click
 * connected to the I2C Extend 2 Click ( Remote Mode ),
 * set default configuration and start measurement.
 *
 * ## Application Task
 * In this example, we read Accel and Mag axis of the connected
 * 6DOF IMU 11 Click boards to the I2C Extend 2 Click ( Remote Mode )
 * which is connected by a LAN cable to I2C Extend 2 Click ( Local Mode ).
 * Results are being sent to the Usart Terminal where you can track their changes.
 * All data logs write on USB uart changes for every 2 sec.
 *
 * @author Stefan Ilic
 *
 */

#include "board.h"
#include "log.h"
#include "i2cextend2.h"

static i2cextend2_t i2cextend2;
static log_t logger;
int16_t axis;

void i2cextend2_6dofimu11_get_axis ( i2cextend2_t *ctx, uint8_t axis_out_reg ) 
{
    uint16_t rx_val = 0;

    rx_val = i2cextend2_rmt_read( ctx, axis_out_reg + 1 );
    rx_val <<= 8;
    rx_val |= i2cextend2_rmt_read( ctx, axis_out_reg );

    axis = ( int16_t ) rx_val;
}

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    i2cextend2_cfg_t i2cextend2_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.
    i2cextend2_cfg_setup( &i2cextend2_cfg );
    I2CEXTEND2_MAP_MIKROBUS( i2cextend2_cfg, MIKROBUS_1 );
    if ( I2C_MASTER_ERROR == i2cextend2_init( &i2cextend2, &i2cextend2_cfg ) ) 
    {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );
        for ( ; ; );
    }

    i2cextend2_enable( &i2cextend2, I2CEXTEND2_EXTEND_ENABLE );

    if ( C6DOFIMU11_WHO_AM_I_WIA_ID == i2cextend2_rmt_read( &i2cextend2, C6DOFIMU11_REG_WHO_AM_I ) ) 
    {
        log_printf( &logger, "        SUCCESS         \r\n" );
        log_printf( &logger, "------------------------\r\n" );
    } 
    else 
    {
        log_printf( &logger, "         ERROR          \r\n" );
        log_printf( &logger, "    Reset the device    \r\n" );
        log_printf( &logger, "------------------------\r\n" );
        for ( ; ; );
    }
    i2cextend2_rmt_write ( &i2cextend2, C6DOFIMU11_REG_CNTL2, C6DOFIMU11_CNTL2_TEMP_EN_STANDBY_MODE |
                                                              C6DOFIMU11_CNTL2_MAG_EN_STANDBY_MODE |
                                                              C6DOFIMU11_CNTL2_ACCEL_EN_STANDBY_MODE );

    i2cextend2_rmt_write ( &i2cextend2, C6DOFIMU11_REG_INC3, C6DOFIMU11_INC3_IEL2_FIFO_TRIG |
                                                             C6DOFIMU11_INC3_IEL1_FIFO_TRIG );

    i2cextend2_rmt_write ( &i2cextend2, C6DOFIMU11_REG_CNTL2, C6DOFIMU11_CNTL2_GSEL_8G |
                                                              C6DOFIMU11_CNTL2_RES_MAX2 |
                                                              C6DOFIMU11_CNTL2_MAG_EN_OPERATING_MODE |
                                                              C6DOFIMU11_CNTL2_ACCEL_EN_OPERATING_MODE );
    Delay_ms ( 100 );
    log_info( &logger, " Application Task " );
    log_printf( &logger, "------------------------\r\n" );
}

void application_task ( void ) 
{
    log_printf( &logger, "\t   Accel   \t|\t    Mag    \r\n" );
    log_printf( &logger, "------------------------------------------------\r\n" );

    i2cextend2_6dofimu11_get_axis( &i2cextend2, C6DOFIMU11_REG_ACCEL_XOUT_L );
    log_printf( &logger, "\t Accel X: %d\t|", axis );
    i2cextend2_6dofimu11_get_axis( &i2cextend2, C6DOFIMU11_REG_MAG_XOUT_L );
    log_printf( &logger, "\t Mag X: %d\r\n", axis );

    i2cextend2_6dofimu11_get_axis( &i2cextend2, C6DOFIMU11_REG_ACCEL_YOUT_L );
    log_printf( &logger, "\t Accel Y: %d\t|", axis );
    i2cextend2_6dofimu11_get_axis( &i2cextend2, C6DOFIMU11_REG_MAG_YOUT_L );
    log_printf( &logger, "\t Mag Y: %d\r\n", axis );

    i2cextend2_6dofimu11_get_axis( &i2cextend2, C6DOFIMU11_REG_ACCEL_ZOUT_L );
    log_printf( &logger, "\t Accel Z: %d\t|", axis );
    i2cextend2_6dofimu11_get_axis( &i2cextend2, C6DOFIMU11_REG_MAG_ZOUT_L );
    log_printf( &logger, "\t Mag Z: %d\r\n", axis );

    log_printf( &logger, "------------------------------------------------\r\n" );
    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