Guide for TCA9548A I2C Multiplexer: ESP32, ESP8266, Arduino
474.Guide for TCA9548A I2C Multiplexer: ESP32, ESP8266, Arduino Using the TCA9458A 1-to-8 I2C Multiplexer, which will be covered in this guide, you will learn how to extend the I2C bus po…
Know the mission before touching a wire.
Understand what you are making, prepare the right tools, and make the workbench safe.
Project details
Guide for TCA9548A I2C Multiplexer: ESP32, ESP8266, Arduino is a iot project. 474.Guide for TCA9548A I2C Multiplexer: ESP32, ESP8266, Arduino Using the TCA9458A 1-to-8 I2C Multiplexer, which will be covered in this guide, you will learn how to extend the I2C bus po…
- Source pages
- 1273-1278
- Named parts
- 3
- Build goal
- Working, tested prototype
Tools you need
- Digital multimeter
- Wire stripper and side cutters
- Soldering iron with a fine tip
- Current-limited bench supply
- Computer with a data-capable USB cable
Use eye protection, good lighting, and a clean insulated surface throughout the build.
Safety precautions
- Disconnect every power source before changing a connection.
- Check component polarity, pinout, and supply voltage twice.
- Use a current limit for the first power-up.
- Keep liquids, loose metal, and uninsulated wires away from the bench.
Gather, identify, and understand every part.
Use the standardized inventory, then open What's this? to learn each part's role, advantages, limitations, handling, and specifications.
What's this?Image, role, pros, cons, handling & specifications
ESP8266
A programmable controller that reads inputs, makes decisions, and drives the project's outputs.
What it does hereIt is the control centre and must use the documented board, pin map, supply, and logic level.
Buy / compare this part ↗Advantages
- Reprogrammable and reusable
- Large learning ecosystem
- Complex behaviour remains changeable
Limitations
- GPIO voltage and current are limited
- Some pins affect boot or communication
- Loads normally need a driver
Handling
- Disconnect power before rewiring
- Avoid static discharge
- Never power motors, relays, or pumps directly from GPIO
Specifications to verify
- Use the exact model, value, package, and rating listed for ESP8266; similar-looking parts are not always interchangeable.
- Confirm operating voltage, logic level, pinout, memory, USB interface, and maximum GPIO current.
What's this?Image, role, pros, cons, handling & specifications
ESP32
A programmable controller that reads inputs, makes decisions, and drives the project's outputs.
What it does hereIt is the control centre and must use the documented board, pin map, supply, and logic level.
Buy / compare this part ↗Advantages
- Reprogrammable and reusable
- Large learning ecosystem
- Complex behaviour remains changeable
Limitations
- GPIO voltage and current are limited
- Some pins affect boot or communication
- Loads normally need a driver
Handling
- Disconnect power before rewiring
- Avoid static discharge
- Never power motors, relays, or pumps directly from GPIO
Specifications to verify
- Use the exact model, value, package, and rating listed for ESP32; similar-looking parts are not always interchangeable.
- Confirm operating voltage, logic level, pinout, memory, USB interface, and maximum GPIO current.
What's this?Image, role, pros, cons, handling & specifications
Power supply
A power component supplies, converts, stores, or regulates energy for the project.
What it does hereIt must provide the documented voltage, polarity, isolation, and sufficient current safely.
Buy / compare this part ↗Advantages
- Stable power improves reliability
- Current limiting protects first tests
- Regulation reduces resets and noise
Limitations
- Wrong polarity can cause immediate damage
- Underrated parts overheat
- Mains circuits require qualified supervision
Handling
- Measure output before connection
- Use a fuse or current limit
- Insulate exposed conductors
Specifications to verify
- Use the exact model, value, package, and rating listed for Power supply; similar-looking parts are not always interchangeable.
- Confirm input/output voltage, current, polarity, connector, isolation, and thermal rating.
Connect one verified path at a time.
Explore the named components and standardized signal flow, then use Source Check to verify exact physical pins, values, and topology before applying power.
Trace this circuit.
Guide for TCA9548A I2C Multiplexer: ESP32, ESP8266, Arduino: interactive parts, standardized terminals, responsive anchored wires, student explanations, and the original circuit reference in one shared system.
Trace before wiring
Follow power, ground, inputs, processing, and outputs in that order. Never guess a pin from package shape alone.
Connect with power off
Make short, labelled connections and share a common ground only where the schematic requires it.
Inspect every joint
Check continuity, polarity, adjacent shorts, and loose connections before the first power-up.
Open all source diagrams and build views 4 visuals
Confirm the hardware-only control path.
This project does not include firmware in the source. The circuit itself provides the required behaviour.
How to connect
- Match every controller label to the circuit view and source pin map.
- Join grounds before signal wires when separate low-voltage supplies are used.
- Keep motors, relays, pumps, and other loads on a suitable driver and external supply.
Common mistakes
Reversed VCC/GND, board-label versus GPIO-number confusion, missing common ground, and charge-only USB cables.
Troubleshoot
Disconnect loads, continuity-test one path at a time, then test with a current limit.
Software preparation
No IDE, board package, library, or firmware upload is required for this project.
If you add a programmable controller as an extension, document its pin map separately.
How to upload code
The original design is implemented entirely in hardware, so proceed after verifying the circuit and supply.
Assemble, deploy, test, and troubleshoot.
Use the complete source notes in build order, then pass the final checks before calling the project finished.
Build in functional stages
- Power and regulation
- Controller or processing stage
- Inputs and sensors
- Outputs and loads
- Enclosure and strain relief
Power up safely
- Inspect unpowered continuity first
- Apply the lowest safe current limit
- Measure supply rails before signals
- Add one load at a time
- Record expected and actual results
Work from simple to complex
- Confirm power, ground, polarity, and orientation
- Compare each pin with the source
- Test inputs separately from outputs
- Replace only one variable at a time
- Power off before every correction
Follow the documented instructions.
These notes come from this project's source and remain in their original order.
Project overview
Project build note474.Guide for TCA9548A I2C Multiplexer: ESP32, ESP8266, Arduino
Using the TCA9458A 1-to-8 I2C Multiplexer, which will be covered in this guide, you will learn how to extend the I2C bus ports on the ESP32, ESP8266, and Arduino. If you wish to control many I2C devices with the same I2C address, then you can utilize this piece of hardware to do so. Multiple OLED panels are another example, as are multiple sensors such as the BME280. Introducing the TCA9548A 1-to-8 I2C Multiplexer You are able to connect with several I2C devices on the same I2C bus thanks to the I2C communication protocol. The only requirement is that
each device have its own distinct I2C address. If, on the other hand, you want to connect numerous I2C devices that have the same address, it will not function. Through the use of a single I2C bus and the TCA9548A I2C multiplexer, you are able to communicate with up to 8 different I2C devices. The I2C communication protocol is utilized in the exchange of information between the multiplexer and the microcontroller. After that, you may use the multiplexer to select which of the I2C buses you want to address. You only need to provide the multiplexer one byte containing the appropriate output port number in order to address a particular port on the device. TCA9548A Multiplexer Features
Here is a list of its most important features
Project build note1 to 8 translating switches capable of bidirectional flow a reset input with active-low threshold There are three address pins, allowing for up to eight TCA9548A devices to be connected to the same I2C bus. I2C bus-based channel selection is provided here. 1.65 V to 5.5 V is the range of acceptable voltage for the operating power supply. 5 V tolerant pins The Circuit Diagram for Multiple OLED Displays Utilizing an I2C Multiplexer
TCA9548A Multiplexer I2C Address I2C is the communication protocol that is utilized when the TCA9548A Multiplexer has a conversation with a microcontroller. Therefore, an I2C address is required. There is room for customization in the multiplexer's address. Adjusting the settings on the A0, A1, and A2 pins allows you to choose a value in the range of 0x70 to 0x77 for the register. Therefore, it is possible to link as many as eight TCA9548A multiplexers to the same I2C bus. This would enable you to connect sixty-four devices that have the same address despite the fact that the microcontroller only has one
I2C bus. If you connect A0, A1, and A2 to GND, for instance, it will cause the multiplexer's address to be set to 0x70. Connect four OLED screens in the manner outlined in the following diagram of a schematic. Buses 2, 3, 4, and 5 are being used by our group. You are free to select a different port number. In addition to that, we will connect A0, A1, and A2 to GND. The address 0x70 is selected for use by the multiplexer as a result of this. Multiple OLED Displays with I2C Multiplexer Code The other displays can be controlled in the same straightforward manner as a single display. Before sending the commands to write to the display, you will first need to make sure that you have selected the appropriate I2C bus.
Demonstration
Project build noteSend the code to your board so it may be run. This is the item that you need to purchase.
An I2C multiplexer makes it very simple to exercise control over numerous OLED displays that each display a unique graphic. As you can see, this is the case.
You built Guide for TCA9548A I2C Multiplexer: ESP32, ESP8266, Arduino.
You followed the full workflow from understanding the mission to testing the finished project. That is a real engineering achievement - well done.
ESP32: Guide for MicroSD Card Module using Arduino IDE
Ready to reuse what you learned in another project from the same track?
Start this project →