Beginner
10 min

Expand I2C bus into four independent channels with TPT29546A and STM32F031K6

Four-channel I2C switch with a reset function

I2C MUX 8 Click with Nucleo 32 with STM32F031K6 MCU

Published Mar 26, 2025

Click board™

I2C MUX 8 Click

Dev. board

Nucleo 32 with STM32F031K6 MCU

Compiler

NECTO Studio

MCU

STM32F031K6

Expand I2C communication with four independent channels for industrial automation, telecom routers, and multi-device system

A

A

Hardware Overview

How does it work?

I2C MUX 8 Click is based on the TPT29546A, a four-channel I2C switch with a reset function from 3PEAK. This bidirectional translating switch allows a single upstream I2C bus (SCL/SDA pair) to be expanded into four independent downstream channels. The selection of active channels is controlled via a programmable register, making it highly flexible for applications that require multiple I2C devices to operate simultaneously without interference. I2C MUX 8 Click is a solution particularly valuable in systems where multiple I2C devices need to coexist without address conflicts. It is commonly used in servers and storage solutions, telecom switching equipment such as routers, and industrial automation. Additionally, it is an ideal choice for products that require multiple identical

I2C devices, such as temperature sensors, ensuring efficient and conflict-free operation in complex embedded systems. I2C MUX 8 Click communicates with MCU using the standard I2C 2-Wire interface that supports Standard-Mode (100 kHz) and Fast-Mode (400 kHz) operation. The TPT29546A has a 7-bit I2C address with the first five MSBs fixed to 1110. The address pins A0, A1, and A2, are programmed by the user and determine the value of the last three LSBs of the I2C address, which can be selected by onboard SMD jumpers labeled as ADDR SEL, allowing selection of the I2C address LSBs. A notable feature of the TPT29546A is its built-in recovery mechanism. If any of the downstream I2C buses become stuck in a LOW state, the active-low reset function (RST pin) can

be used to restore normal operation. By pulling the RST pin LOW, the internal I2C state machine is reset, and all channels are deselected. Additionally, the device includes an internal power-on reset feature, ensuring a stable startup by resetting all channels to their default state. 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 MUX 8 Click hardware overview image

Features overview

Development board

Nucleo 32 with STM32F031K6 MCU board provides an affordable and flexible platform for experimenting with STM32 microcontrollers in 32-pin packages. Featuring Arduino™ Nano connectivity, it allows easy expansion with specialized shields, while being mbed-enabled for seamless integration with online resources. The

board includes an on-board ST-LINK/V2-1 debugger/programmer, supporting USB reenumeration with three interfaces: Virtual Com port, mass storage, and debug port. It offers a flexible power supply through either USB VBUS or an external source. Additionally, it includes three LEDs (LD1 for USB communication, LD2 for power,

and LD3 as a user LED) and a reset push button. The STM32 Nucleo-32 board is supported by various Integrated Development Environments (IDEs) such as IAR™, Keil®, and GCC-based IDEs like AC6 SW4STM32, making it a versatile tool for developers.

Nucleo 32 with STM32F031K6 MCU double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

ARM Cortex-M0

MCU Memory (KB)

32

Silicon Vendor

STMicroelectronics

Pin count

32

RAM (Bytes)

4096

You complete me!

Accessories

Click Shield for Nucleo-32 is the perfect way to expand your development board's functionalities with STM32 Nucleo-32 pinout. The Click Shield for Nucleo-32 provides two mikroBUS™ sockets to add any functionality from our ever-growing range of Click boards™. We are fully stocked with everything, from sensors and WiFi transceivers to motor control and audio amplifiers. The Click Shield for Nucleo-32 is compatible with the STM32 Nucleo-32 board, providing an affordable and flexible way for users to try out new ideas and quickly create prototypes with any STM32 microcontrollers, choosing from the various combinations of performance, power consumption, and features. The STM32 Nucleo-32 boards do not require any separate probe as they integrate the ST-LINK/V2-1 debugger/programmer and come with the STM32 comprehensive software HAL library and various packaged software examples. This development platform provides users with an effortless and common way to combine the STM32 Nucleo-32 footprint compatible board with their favorite Click boards™ in their upcoming projects.

Click Shield for Nucleo-32 accessories 1 image

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
Reset
PA11
RST
ID COMM
PA4
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
PB6
SCL
I2C Data
PB7
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

I2C MUX 8 Click Schematic schematic

Step by step

Project assembly

Click Shield for Nucleo-144 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Nucleo 32 with STM32F031K6 MCU as your development board.

Click Shield for Nucleo-144 front image hardware assembly
Nucleo 144 with STM32L4A6ZG MCU front image hardware assembly
Stepper 22 Click front image hardware assembly
Prog-cut hardware assembly
Stepper 22 Click complete accessories setup image hardware assembly
Board mapper by product8 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
STM32 M4 Clicker HA MCU/Select 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

Software Support

Library Description

I2C MUX 8 Click demo application is developed using the NECTO Studio, ensuring compatibility with mikroSDK's open-source libraries and tools. Designed for plug-and-play implementation and testing, the demo is fully compatible with all development, starter, and mikromedia boards featuring a mikroBUS™ socket.

Example Description
This example demonstrates the use of I2C MUX 8 Click board by reading the device ID of a 6DOF IMU 11 and Compass 3 Click boards connected to the channels 1 and 4 respectfully.

Key functions:

  • i2cmux8_cfg_setup - This function initializes Click configuration structure to initial values.

  • i2cmux8_init - This function initializes all necessary pins and peripherals used for this Click board.

  • i2cmux8_set_channel - This function sets the active channel and updates the slave address for communication.

  • i2cmux8_read_channel - This function reads the currently selected channel.

  • i2cmux8_i2c_read_reg - This function reads data from a specific register of the currently active I2C slave.

Application Init
Initializes the driver and resets the device.

Application Task
Reads the device ID of the connected Click boards. Channel 1 : 6DOF IMU 11 Click [slave address: 0x0E; reg: 0x00; id: 0x2D], Channel 4 : Compass 3 Click [slave address: 0x30; reg: 0x2F; id: 0x0C]. All data is being logged on the USB UART where you can check the device ID.

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 MUX 8 Click example
 *
 * # Description
 * This example demonstrates the use of I2C MUX 8 Click board by reading the
 * device ID of a 6DOF IMU 11 and Compass 3 Click boards connected to 
 * the channels 1 and 4 respectfully.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes the driver and resets the device.
 *
 * ## Application Task
 * Reads the device ID of the connected Click boards.
 * Channel 1 : 6DOF IMU 11 Click [slave address: 0x0E; reg: 0x00; id: 0x2D],
 * Channel 4 : Compass 3 Click   [slave address: 0x30; reg: 0x2F; id: 0x0C].
 * All data is being logged on the USB UART where you can check the device ID.
 *
 * @author Stefan Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "i2cmux8.h"

#define DEVICE0_NAME                "6DOF IMU 11 Click"
#define DEVICE0_POSITION            I2CMUX8_CHANNEL_1
#define DEVICE0_SLAVE_ADDRESS       0x0E
#define DEVICE0_REG_ID              0x00
#define DEVICE0_ID                  0x2D

#define DEVICE1_NAME                "Compass 3 Click"
#define DEVICE1_POSITION            I2CMUX8_CHANNEL_4
#define DEVICE1_SLAVE_ADDRESS       0x30
#define DEVICE1_REG_ID              0x2F
#define DEVICE1_ID                  0x0C

static i2cmux8_t i2cmux8;
static log_t logger;

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    i2cmux8_cfg_t i2cmux8_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.
    i2cmux8_cfg_setup( &i2cmux8_cfg );
    I2CMUX8_MAP_MIKROBUS( i2cmux8_cfg, MIKROBUS_1 );
    if ( I2C_MASTER_ERROR == i2cmux8_init( &i2cmux8, &i2cmux8_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    i2cmux8_reset_device ( &i2cmux8 );
    
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
    uint8_t channel = 0, device_id = 0;
    if ( I2CMUX8_OK == i2cmux8_set_channel ( &i2cmux8, DEVICE0_POSITION, DEVICE0_SLAVE_ADDRESS ) )
    {
        if ( I2CMUX8_OK == i2cmux8_read_channel ( &i2cmux8, &channel ) )
        {
            log_printf( &logger, " --- Channel %u --- \r\n", ( uint16_t ) channel );
        }
        if ( I2CMUX8_OK == i2cmux8_i2c_read_reg ( &i2cmux8, DEVICE0_REG_ID, &device_id, 1 ) )
        {
            log_printf( &logger, " %s - Device ID: 0x%.2X \r\n\n", ( char * ) DEVICE0_NAME, ( uint16_t ) device_id );
        }
        Delay_ms ( 1000 );
    }
    if ( I2CMUX8_OK == i2cmux8_set_channel ( &i2cmux8, DEVICE1_POSITION, DEVICE1_SLAVE_ADDRESS ) )
    {
        if ( I2CMUX8_OK == i2cmux8_read_channel ( &i2cmux8, &channel ) )
        {
            log_printf( &logger, " --- Channel %u --- \r\n", ( uint16_t ) channel );
        }
        if ( I2CMUX8_OK == i2cmux8_i2c_read_reg ( &i2cmux8, DEVICE1_REG_ID, &device_id, 1 ) )
        {
            log_printf( &logger, " %s - Device ID: 0x%.2X \r\n\n", ( char * ) DEVICE1_NAME, ( uint16_t ) device_id );
        }
        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

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.