10 min

Achieve the perfect blend of safety and efficiency in your I2C communications with ISO1644 and STM32F767BI

Put an end to signal interference and data loss

I2C Isolator 5 Click with UNI-DS v8

Published Nov 09, 2023

Click board™

I2C Isolator 5 Click

Development board



NECTO Studio



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



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

UNI-DS 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 STM32, Kinetis, TIVA, CEC, MSP, PIC, dsPIC, PIC32, and AVR MCUs regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer over WiFi. 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, UNI-DS v8 provides a fluid and immersive working experience, allowing access anywhere and under any

circumstances at any time. Each part of the UNI-DS 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. UNI-DS 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.

UNI-DS v8 horizontal image

Microcontroller Overview

MCU Card / MCU



8th Generation


ARM Cortex-M7

MCU Memory (KB)


Silicon Vendor


Pin count


RAM (Bytes)


Used MCU Pins

mikroBUS™ mapper

Output B Channel
Chip Select
Power Supply
Output A Channel
Input A Channel
I2C Clock
I2C Data
Power Supply

Take a closer look


I2C Isolator 5 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 UNI-DS 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

After pressing the "FLASH" button on the left-side panel, it is necessary to open the UART terminal to display the achieved results. By clicking on the Tools icon in the right-hand panel, multiple different functions are displayed, among which is the UART Terminal. Click on the offered "UART Terminal" icon.

UART Application Output Step 1

Once the UART terminal is opened, the window takes on a new form. At the top of the tab are two buttons, one for adjusting the parameters of the UART terminal and the other for connecting the UART terminal. The tab's lower part is reserved for displaying the achieved results. Before connecting, the terminal has a Disconnected status, indicating that the terminal is not yet active. Before connecting, it is necessary to check the set parameters of the UART terminal. Click on the "OPTIONS" button.

UART Application Output Step 2

In the newly opened UART Terminal Options field, we check if the terminal settings are correct, such as the set port and the Baud rate of UART communication. If the data is not displayed properly, it is possible that the Baud rate value is not set correctly and needs to be adjusted to 115200. If all the parameters are set correctly, click on "CONFIGURE".

UART Application Output Step 3

The next step is to click on the "CONNECT" button, after which the terminal status changes from Disconnected to Connected in green, and the data is displayed in the Received data field.

UART Application Output Step 4

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

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 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_PRESS_SCALE_FACTOR                   1200
#define I2CISOLATOR5_VAV_PRESS_TEMP_SCALE_FACTOR                    72
#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 };
    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;
        readout_data = rx_buf[ 3 ];
        readout_data <<= 8;
        readout_data |= rx_buf[ 2 ];
        temperature = ( float ) readout_data;
    return error_flag;

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

Additional Support