Intermediate
30 min

Experience peace of mind as you securely isolate I2C communication using CPC5902 and TM4C129EKCPDT

I2C data's Fort Knox: Secure isolation, seamless communication!

I2C Isolator 3 Click with Fusion for Tiva v8

Published Sep 03, 2023

Click board™

I2C Isolator 3 Click

Dev. board

Fusion for Tiva v8

Compiler

NECTO Studio

MCU

TM4C129EKCPDT

Our I2C communication isolator solution shields your data from interference and noise, ensuring secure and reliable communication in sensitive applications

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Hardware Overview

How does it work?

I2C Isolator 3 Click is based on the CPC5902, a dual optically isolated bidirectional logic-bus repeater from IXYS Integrated Circuits Division. It bidirectionally buffers the two I2C signals across the isolation barrier and supports I2C clock stretching while providing 3750Vrms of galvanic isolation. The buffered signals will always return to their proper value after a transient interruption on either side. Unlike competitive magnetically isolated digital isolators, transformers, or capacitive isolators, the CPC5902 doesn’t need to be clocked periodically to sustain the logic states. Besides, it offers glitch-free operation, excellent reliability, and a very long operational life. If different supply voltage levels are used at each power supply side, it can also function as a logic

level translator for levels as low as 2.7V or as high as 5.5V. This optically coupled I2C bus repeater is ideal for Power-over-Ethernet (PoE) applications, buffering and isolating the clock and data signals between the host controller and the Power Supply Equipment (PSE) controller. Additional applications include a power supply high-side interface, an I2C bus length extender, and isolated signal monitoring and control. An extensive operational power supply range of 2.7V to 5.5V enables I2C logic-level translation applications. I2C Isolator 3 Click communicates with MCU using the standard I2C 2-Wire interface and supports both Standard and Fast Mode with a transfer rate of up to 400kbps. The CPC5902 is also fully compatible with any single or double-wire bus in the

frequency range from 0 Hz to 500 kHz, corresponding to a 400 kbps transfer rate for the I2C bus. It also possesses two terminals labeled as VIN and I2C at the bottom of the Click board™, where VIN represents the B-side power supply of the repeater, while the other I2C corresponds to the isolated bidirectional logic-bus terminal. 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 3 Click hardware overview image

Features overview

Development board

Fusion for TIVA v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports a wide range of microcontrollers, such as different 32-bit ARM® Cortex®-M based MCUs from Texas Instruments, regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer over a WiFi network. The development board is well organized and designed so that the end-user has all the necessary elements, such as switches, buttons, indicators, connectors, and others, in one place. Thanks to innovative manufacturing technology, Fusion for TIVA v8 provides a fluid and immersive working experience, allowing access

anywhere and under any circumstances at any time. Each part of the Fusion for TIVA v8 development board contains the components necessary for the most efficient operation of the same board. An advanced integrated CODEGRIP programmer/debugger module offers many valuable programming/debugging options, including support for JTAG, SWD, and SWO Trace (Single Wire Output)), and seamless integration with the Mikroe software environment. Besides, it also includes a clean and regulated power supply module for the development board. It can use a wide range of external power sources, including a battery, an external 12V power supply, and a power source via the USB Type-C (USB-C) connector.

Communication options such as USB-UART, USB HOST/DEVICE, CAN (on the MCU card, if supported), and Ethernet is also included. In addition, it also has the well-established mikroBUS™ standard, a standardized socket for the MCU card (SiBRAIN standard), and two display options for the TFT board line of products and character-based LCD. Fusion for TIVA v8 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.

Fusion for Tiva v8 horizontal image

Microcontroller Overview

MCU Card / MCU

default

Type

8th Generation

Architecture

ARM Cortex-M4

MCU Memory (KB)

512

Silicon Vendor

Texas Instruments

Pin count

128

RAM (Bytes)

262144

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
NC
NC
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
NC
NC
INT
NC
NC
TX
NC
NC
RX
I2C Clock
PD2
SCL
I2C Data
PD3
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

I2C Isolator 3 Click Schematic schematic

Step by step

Project assembly

Fusion for PIC v8 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Fusion for Tiva v8 as your development board.

Fusion for PIC v8 front image hardware assembly
GNSS2 Click front image hardware assembly
SiBRAIN for PIC32MZ1024EFK144 front image hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
v8 SiBRAIN 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 Compiler Selection Step Image hardware assembly
NECTO Output Selection Step Image hardware assembly
Necto image step 6 hardware assembly
Necto image step 7 hardware assembly
Necto image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto PreFlash Image 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 3 Click driver.

Key functions:

  • i2cisolator3_send_cmd - This function sends the desired command to a remote device wired with CPC5902

  • i2cisolator3_write_byte - This function writes the byte of data to the targeted 8-bit register address of the remote device wired with CPC5902

  • i2cisolator3_read_byte - This function read a the byte of data from the targeted 8-bit register address of the remote device wired with CPC5902

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 I2CIsolator3 Click example
 *
 * # Description
 * This is an example that demonstrates the use of the I2C Isolator 3 click board. In this example, we measure temperature
 * from the Thermo 20 click connected to the I2C Isolator 3 click board. 
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes I2C and start to write log. Initialization driver enables - I2C,
 * set I2C slave address of the Thermo 20 click, performs software reset, also write log.
 *
 * ## Application Task
 * In this example via Thermo 20 click we get the data processed by the function. When the function processes the data, we get
 * the temperature information. All data logs write on USB UART changes every 3 sec.
 *
 * Additional Functions :
 * - void calculate_temperature( ) - Calculate temperature in degrees Celsius.
 *
 * @author Jelena Milosavljevic
 *
 */

#include "board.h"
#include "log.h"
#include "i2cisolator3.h"

static i2cisolator3_t i2cisolator3;
static log_t logger;
static float temperature;
static char log_text[ 50 ];

void calculate_temperature ( ) {
    uint16_t res_adc;
    uint8_t rx_buf[ 3 ];

    i2cisolator3_burst_read ( &i2cisolator3, I2CISOLATOR3_THERMO20_CMD_READ_ADC, rx_buf, 3 );

    res_adc = rx_buf[ 0 ];
    res_adc <<= 8;
    res_adc |= rx_buf[ 1 ];

    temperature = ( float ) res_adc;
    temperature /= 65535.0;
    temperature *= 165.0;
    temperature -= 40.0;
}

void application_init ( void ) {
    log_cfg_t log_cfg;                         /**< Logger config object. */
    i2cisolator3_cfg_t i2cisolator3_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.
    i2cisolator3_cfg_setup( &i2cisolator3_cfg );
    I2CISOLATOR3_MAP_MIKROBUS( i2cisolator3_cfg, MIKROBUS_1 );
    err_t init_flag = i2cisolator3_init( &i2cisolator3, &i2cisolator3_cfg );
    if ( I2C_MASTER_ERROR == init_flag ) {
        
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );

        for ( ; ; );
    }
    log_printf( &logger, "  Driver Init. Done  \r\n" );
    log_printf( &logger, "  Set I2C Slave Address   \r\n" );
    log_printf( &logger, "  of the Thermo 20 click   \r\n" );
    Delay_ms( 100 );
    
    log_printf( &logger, "--------------------------\r\n" );
    log_printf( &logger, "      Software Reset      \r\n" );
    i2cisolator3_send_cmd(  &i2cisolator3, I2CISOLATOR3_THERMO20_CMD_RESET );
    Delay_ms( 100 );

    log_printf( &logger, "--------------------------\r\n" );
    log_printf( &logger, "     Start Measuring      \r\n" );
    log_printf( &logger, "--------------------------\r\n" );
    Delay_ms( 100 );

    log_info( &logger, " Application Task \r\n" );
}

void application_task ( void ) {
    i2cisolator3_send_cmd( &i2cisolator3, I2CISOLATOR3_THERMO20_CMD_CONVERSION );
    Delay_ms( 100 );

    calculate_temperature( );

    log_printf( &logger, "Temperature : %.2f \r\n", temperature );
    Delay_ms( 3000 );    
}

void main ( void ) {
    application_init( );

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

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

Additional Support

Resources

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