Beginner
10 min

Expand I2C bus into four independent channels with TPT29546A and PIC18F57Q43

Four-channel I2C switch with a reset function

I2C MUX 8 Click with Curiosity Nano with PIC18F57Q43

Published Mar 26, 2025

Click board™

I2C MUX 8 Click

Dev. board

Curiosity Nano with PIC18F57Q43

Compiler

NECTO Studio

MCU

PIC18F57Q43

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

PIC18F57Q43 Curiosity Nano evaluation kit is a cutting-edge hardware platform designed to evaluate microcontrollers within the PIC18-Q43 family. Central to its design is the inclusion of the powerful PIC18F57Q43 microcontroller (MCU), offering advanced functionalities and robust performance. Key features of this evaluation kit include a yellow user LED and a responsive

mechanical user switch, providing seamless interaction and testing. The provision for a 32.768kHz crystal footprint ensures precision timing capabilities. With an onboard debugger boasting a green power and status LED, programming and debugging become intuitive and efficient. Further enhancing its utility is the Virtual serial port (CDC) and a debug GPIO channel (DGI

GPIO), offering extensive connectivity options. Powered via USB, this kit boasts an adjustable target voltage feature facilitated by the MIC5353 LDO regulator, ensuring stable operation with an output voltage ranging from 1.8V to 5.1V, with a maximum output current of 500mA, subject to ambient temperature and voltage constraints.

PIC18F57Q43 Curiosity Nano double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

PIC

MCU Memory (KB)

128

Silicon Vendor

Microchip

Pin count

48

RAM (Bytes)

8196

You complete me!

Accessories

Curiosity Nano Base for Click boards is a versatile hardware extension platform created to streamline the integration between Curiosity Nano kits and extension boards, tailored explicitly for the mikroBUS™-standardized Click boards and Xplained Pro extension boards. This innovative base board (shield) offers seamless connectivity and expansion possibilities, simplifying experimentation and development. Key features include USB power compatibility from the Curiosity Nano kit, alongside an alternative external power input option for enhanced flexibility. The onboard Li-Ion/LiPo charger and management circuit ensure smooth operation for battery-powered applications, simplifying usage and management. Moreover, the base incorporates a fixed 3.3V PSU dedicated to target and mikroBUS™ power rails, alongside a fixed 5.0V boost converter catering to 5V power rails of mikroBUS™ sockets, providing stable power delivery for various connected devices.

Curiosity Nano Base for Click boards accessories 1 image

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
Reset
PA7
RST
ID COMM
PD4
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
PB2
SCL
I2C Data
PB1
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

Curiosity Nano Base for Click boards front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Curiosity Nano with PIC18F57Q43 as your development board.

Curiosity Nano Base for Click boards front image hardware assembly
Charger 27 Click front image hardware assembly
PIC18F47Q10 Curiosity Nano front image hardware assembly
Prog-cut hardware assembly
Charger 27 Click complete accessories setup image hardware assembly
Curiosity Nano with PICXXX 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
PIC18F57Q43 Curiosity 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

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

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