Manage I2C communications across multiple devices with TCA9548A and PIC18F57Q43
8-in-1 bidirectional bliss
Published Feb 13, 2024
Click board™
I2C MUX 3 Click
Dev Board
Curiosity Nano with PIC18F57Q43
Compiler
NECTO Studio
MCU
PIC18F57Q43
Unlock the power of bidirectional translating switches to seamlessly connect and control a wide array of I2C-enabled devices, simplifying your integration process
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Hardware Overview
How does it work?
I2C MUX 3 Click is based on the TCA9548A, a low voltage eight bidirectional translating switch with an active-low reset input controlled through the I2C serial interface from Texas Instruments. The master SCL/SDA signal pair is directed to eight channels of slave devices, SC0/SD0-SC7/SD7, where any individual downstream channel can be selected and any combination of the eight channels. It features I2C control using a single 8-bit control register in which each bit controls the enabling and disabling of one of the corresponding eight switch channels for I2C data flow. This Click board™ includes a low dropout linear regulator AP7331 from Diodes Incorporated to provide the 2.45V supply voltage for the TCA9548A. When the TCA9548APWR is turned on for the first time or at any time, the device needs
to be reset by cycling the power supply, which means that the Power-On reset requirements must be followed to ensure the I2C bus logic is appropriately initialized. Additionally, suppose communication on the I2C bus enters a fault state. In that case, the TCA9548A can be reset to resume normal operation using the RST pin feature or by a Power-On reset, which results from cycling power to the device. I2C MUX 3 Click communicates with MCU using the standard I2C 2-Wire interface that supports Standard-Mode (100 kHz) and Fast-Mode (400 kHz) operations. The TCA9548A 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. It 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 TCA9548A 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. More information about the TCA9548A can be found in the attached datasheet. 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
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.
Microcontroller Overview
MCU Card / MCU
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.
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the Curiosity Nano with PIC18F57Q43 as your development board.
Track your results in real time
Application Output via Debug Mode
1. Once the code example is loaded, pressing the "DEBUG" button initiates the build process, programs it on the created setup, and enters Debug mode.
2. After the programming is completed, a header with buttons for various actions within the IDE becomes visible. Clicking the green "PLAY" button starts reading the results achieved with the Click board™. The achieved results are displayed in the Application Output tab.
Software Support
Library Description
This library contains API for I2C MUX 3 Click driver.
Key functions:
i2cmux3_rd_slv- Slave Device Read functioni2cmux3_dev_enable- Device enable functioni2cmux3_hw_rst- Hardware reset 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
* \brief I2cMux3 Click example
*
* # Description
* This example demonstrates the use of I2C MUX 3 Click board.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initalizes the driver, preforms hardware reset, then enables channel 0 and
* makes an initial log.
*
* ## Application Task
* Reads the device ID of a 6DOF IMU 12 click (dev ID: 0x24) and displays it
* on the USB UART each second.
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "i2cmux3.h"
// ------------------------------------------------------------------ VARIABLES
static i2cmux3_t i2cmux3;
static log_t logger;
uint8_t id_val;
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
i2cmux3_cfg_t cfg;
/**
* 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.
i2cmux3_cfg_setup( &cfg );
I2CMUX3_MAP_MIKROBUS( cfg, MIKROBUS_1 );
i2cmux3_init( &i2cmux3, &cfg );
Delay_ms( 100 );
i2cmux3_hw_rst( &i2cmux3 );
Delay_ms( 100 );
i2cmux3_ch_sel( &i2cmux3, 0 );
log_printf( &logger, " Please connect a 6DOF IMU 12 click to channel 0\r\n" );
log_printf( &logger, "-------------------------------\r\n" );
Delay_ms( 2000 );
}
void application_task ( void )
{
i2cmux3_rd_slv ( &i2cmux3, 0x68, 0x00, &id_val, 1 );
log_printf( &logger, " The click device ID is: 0x%.2X \r\n", ( uint16_t ) id_val );
log_printf( &logger, "-------------------------------\r\n" );
Delay_ms( 1000 );
}
void main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
