Manage I2C communications across multiple devices with TCA9548A and STM32F091RC
8-in-1 bidirectional bliss
Published Feb 26, 2024
Click board™
I2C MUX 3 Click
Dev Board
Nucleo-64 with STM32F091RC MCU
Compiler
NECTO Studio
MCU
STM32F091RC
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
Nucleo-64 with STM32F091RC MCU offers a cost-effective and adaptable platform for developers to explore new ideas and prototype their designs. This board harnesses the versatility of the STM32 microcontroller, enabling users to select the optimal balance of performance and power consumption for their projects. It accommodates the STM32 microcontroller in the LQFP64 package and includes essential components such as a user LED, which doubles as an ARDUINO® signal, alongside user and reset push-buttons, and a 32.768kHz crystal oscillator for precise timing operations. Designed with expansion and flexibility in mind, the Nucleo-64 board features an ARDUINO® Uno V3 expansion connector and ST morpho extension pin
headers, granting complete access to the STM32's I/Os for comprehensive project integration. Power supply options are adaptable, supporting ST-LINK USB VBUS or external power sources, ensuring adaptability in various development environments. The board also has an on-board ST-LINK debugger/programmer with USB re-enumeration capability, simplifying the programming and debugging process. Moreover, the board is designed to simplify advanced development with its external SMPS for efficient Vcore logic supply, support for USB Device full speed or USB SNK/UFP full speed, and built-in cryptographic features, enhancing both the power efficiency and security of projects. Additional connectivity is
provided through dedicated connectors for external SMPS experimentation, a USB connector for the ST-LINK, and a MIPI® debug connector, expanding the possibilities for hardware interfacing and experimentation. Developers will find extensive support through comprehensive free software libraries and examples, courtesy of the STM32Cube MCU Package. This, combined with compatibility with a wide array of Integrated Development Environments (IDEs), including IAR Embedded Workbench®, MDK-ARM, and STM32CubeIDE, ensures a smooth and efficient development experience, allowing users to fully leverage the capabilities of the Nucleo-64 board in their projects.
Microcontroller Overview
MCU Card / MCU
Architecture
ARM Cortex-M0
MCU Memory (KB)
256
Silicon Vendor
STMicroelectronics
Pin count
64
RAM (Bytes)
32768
You complete me!
Accessories
Click Shield for Nucleo-64 comes equipped with two proprietary mikroBUS™ sockets, allowing all the Click board™ devices to be interfaced with the STM32 Nucleo-64 board with no effort. This way, Mikroe allows its users to add any functionality from our ever-growing range of Click boards™, such as WiFi, GSM, GPS, Bluetooth, ZigBee, environmental sensors, LEDs, speech recognition, motor control, movement sensors, and many more. More than 1537 Click boards™, which can be stacked and integrated, are at your disposal. The STM32 Nucleo-64 boards are based on the microcontrollers in 64-pin packages, a 32-bit MCU with an ARM Cortex M4 processor operating at 84MHz, 512Kb Flash, and 96KB SRAM, divided into two regions where the top section represents the ST-Link/V2 debugger and programmer while the bottom section of the board is an actual development board. These boards are controlled and powered conveniently through a USB connection to program and efficiently debug the Nucleo-64 board out of the box, with an additional USB cable connected to the USB mini port on the board. Most of the STM32 microcontroller pins are brought to the IO pins on the left and right edge of the board, which are then connected to two existing mikroBUS™ sockets. This Click Shield also has several switches that perform functions such as selecting the logic levels of analog signals on mikroBUS™ sockets and selecting logic voltage levels of the mikroBUS™ sockets themselves. Besides, the user is offered the possibility of using any Click board™ with the help of existing bidirectional level-shifting voltage translators, regardless of whether the Click board™ operates at a 3.3V or 5V logic voltage level. Once you connect the STM32 Nucleo-64 board with our Click Shield for Nucleo-64, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.
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 Nucleo-64 with STM32F091RC MCU 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
