Experience the freedom to connect and control an array of I2C devices with PI4MSD5V9547 and PIC18F4458

Multiplexing marvel: I2C device management perfected!

Published Nov 01, 2023

Click board™

I2C MUX 7 Click

Dev Board

Curiosity HPC

Compiler

NECTO Studio

MCU

PIC18F4458

Effortlessly manage your I2C device network with our multiplexer solution, making it an essential tool for engineers and developers seeking efficient and reliable communication in their projects

Hardware Overview

How does it work?

I2C MUX 7 Click is based on the PI4MSD5V9547, a low voltage octal bidirectional translating multiplexer with an active-low reset input controlled through the I2C serial interface from Texas Instruments. The host SCL/SDA signal pair is directed to eight channels CH0-CH7, where only one SCL/SDA channel can be selected at a time, determined by the contents of the programmable control register. The board powers up with Channel 0 connected, allowing immediate communication between the Host and downstream devices on that channel. This Click board™ includes a low dropout linear regulator AP2112 from Diodes Incorporated to provide the 1.8V supply voltage for the PI4MSD5V9547. When power is applied to the IC, an internal Power-On

Reset (POR) holds the PI4MSD5V9547 in a reset condition until the power supply reaches the POR voltage level. At this point, the reset condition is released, and the PI4MSD5V9547 registers and I2C-bus state machine are initialized to their default states (all zeroes), causing deselection of all channels. I2C MUX 7 Click communicates with MCU using the standard I2C 2-Wire interface that supports Standard-Mode (100 kHz) and Fast-Mode (400 kHz) operations. The PI4MSD5V9547 has a 7-bit slave 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 slave address, which can be selected by onboard SMD jumpers labeled as ADDR SEL, allowing selection of the slave

address LSBs. Alongside the internal Power-On Reset (POR) function, this board also has an active-low reset signal routed on the RST pin of the mikroBUS™ socket used to recover from a bus-fault condition. When this signal is asserted low, the PI4MSD5V9547 resets its registers alongside the I2C state machine and deselects all channels. 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

Curiosity HPC, standing for Curiosity High Pin Count (HPC) development board, supports 28- and 40-pin 8-bit PIC MCUs specially designed by Microchip for the needs of rapid development of embedded applications. This board has two unique PDIP sockets, surrounded by dual-row expansion headers, allowing connectivity to all pins on the populated PIC MCUs. It also contains a powerful onboard PICkit™ (PKOB), eliminating the need for an external programming/debugging tool, two mikroBUS™ sockets for Click board™ connectivity, a USB connector, a set of indicator LEDs, push button switches and a variable potentiometer. All

these features allow you to combine the strength of Microchip and Mikroe and create custom electronic solutions more efficiently than ever. Each part of the Curiosity HPC development board contains the components necessary for the most efficient operation of the same board. An integrated onboard PICkit™ (PKOB) allows low-voltage programming and in-circuit debugging for all supported devices. When used with the MPLAB® X Integrated Development Environment (IDE, version 3.0 or higher) or MPLAB® Xpress IDE, in-circuit debugging allows users to run, modify, and troubleshoot their custom software and hardware

quickly without the need for additional debugging tools. Besides, it includes a clean and regulated power supply block for the development board via the USB Micro-B connector, alongside all communication methods that mikroBUS™ itself supports. Curiosity HPC development board allows you to create a new application in just a few steps. Natively supported by Microchip software tools, it covers many aspects of prototyping thanks to many number of different Click boards™ (over a thousand boards), the number of which is growing daily.

Microcontroller Overview

MCU Card / MCU

Architecture

PIC

MCU Memory (KB)

Silicon Vendor

Microchip

Pin count

RAM (Bytes)

2048

Used MCU Pins

mikroBUS™ mapper

Reset

RD0

RST

SCK

MISO

MOSI

Power Supply

3.3V

Ground

GND

PWM

INT

I2C Clock

RC3

SCL

I2C Data

RC4

SDA

Power Supply

Ground

GND

Take a closer look

Schematic

Step by step

Project assembly

Curiosity HPC front no-mcu image hardware assembly

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

GNSS2 Click front image hardware assembly

GNSS2 Click complete accessories setup image hardware assembly

Curiosity HPC Access MB 1 - upright/background hardware assembly

Necto DIP image step 7 hardware assembly

Necto No Display image step 8 hardware assembly

Debug Image Necto Step hardware assembly

Track your results in real time

Application Output

After loading the code example, pressing the "DEBUG" button builds and programs it on the selected setup.

After programming is completed, a header with buttons for various actions available in the IDE appears. By clicking the green "PLAY "button, we start reading the results achieved with Click board™.

Upon completion of programming, the Application Output tab is automatically opened, where the achieved result can be read. In case of an inability to perform the Debug function, check if a proper connection between the MCU used by the setup and the CODEGRIP programmer has been established. A detailed explanation of the CODEGRIP-board connection can be found in the CODEGRIP User Manual. Please find it in the RESOURCES section.

Software Support

Library Description

This library contains API for I2C MUX 7 Click driver.

Key functions:

i2cmux7_set_channel - This function sets the desired channel active and configures its slave address
i2cmux7_read_channel - This function reads the currently selected channel value
i2cmux7_generic_read - This function reads a desired number of data bytes starting from the selected register by using I2C serial interface

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 I2CMUX7 Click example
 *
 * # Description
 * This example demonstrates the use of I2C MUX 7 click board by reading the
 * device ID of a 6DOF IMU 11 and Compass 3 click boards connected to 
 * the channels 0 and 7 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 0 : 6DOF IMU 11 click [slave address: 0x0E; reg: 0x00; id: 0x2D],
 * Channel 7 : 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 "i2cmux7.h"

#define DEVICE0_NAME                "6DOF IMU 11 click"
#define DEVICE0_POSITION            I2CMUX7_CHANNEL_0
#define DEVICE0_SLAVE_ADDRESS       0x0E
#define DEVICE0_REG_ID              0x00
#define DEVICE0_ID                  0x2D

#define DEVICE1_NAME                "Compass 3 click"
#define DEVICE1_POSITION            I2CMUX7_CHANNEL_7
#define DEVICE1_SLAVE_ADDRESS       0x30
#define DEVICE1_REG_ID              0x2F
#define DEVICE1_ID                  0x0C

static i2cmux7_t i2cmux7;
static log_t logger;

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    i2cmux7_cfg_t i2cmux7_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.
    i2cmux7_cfg_setup( &i2cmux7_cfg );
    I2CMUX7_MAP_MIKROBUS( i2cmux7_cfg, MIKROBUS_1 );
    if ( I2C_MASTER_ERROR == i2cmux7_init( &i2cmux7, &i2cmux7_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    i2cmux7_reset_device ( &i2cmux7 );
    
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
    uint8_t channel, device_id;
    if ( I2CMUX7_OK == i2cmux7_set_channel ( &i2cmux7, DEVICE0_POSITION, DEVICE0_SLAVE_ADDRESS ) )
    {
        if ( I2CMUX7_OK == i2cmux7_read_channel ( &i2cmux7, &channel ) )
        {
            log_printf( &logger, " --- Channel %u --- \r\n", ( uint16_t ) ( channel & I2CMUX7_CHANNEL_NUM_MASK ) );
        }
        if ( I2CMUX7_OK == i2cmux7_generic_read ( &i2cmux7, 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 ( I2CMUX7_OK == i2cmux7_set_channel ( &i2cmux7, DEVICE1_POSITION, DEVICE1_SLAVE_ADDRESS ) )
    {
        if ( I2CMUX7_OK == i2cmux7_read_channel ( &i2cmux7, &channel ) )
        {
            log_printf( &logger, " --- Channel %u --- \r\n", ( uint16_t ) ( channel & I2CMUX7_CHANNEL_NUM_MASK ) );
        }
        if ( I2CMUX7_OK == i2cmux7_generic_read ( &i2cmux7, 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 );
    }
}

void main ( void ) 
{
    application_init( );

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

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