I3C Explained: What It Is, How It Works, and Why Modern Devices Need It

Did you ever wonder how your smartphone or smartwatch speaks to all of those tiny sensors so smoothly? Or how the dashboard of your car gathers information from dozens of parts without missing a beat? 

The secret lies in serial communication protocols, the unnoticed mechanisms that allow chips and sensors to communicate with one another. This was well taken care of by older standards, such as I2C and SPI, over the years. However, as devices became smarter and packed with more sensors, a new solution was required. 

I3C was introduced as a solution at this stage. It is considered the next phase of serial communication. Short for Improved Inter-Integrated Circuit, it helps devices communicate at higher rates, consume less energy, and work better together while keeping things simple for designers. 

We shall discuss in this blog what is special about I3C, why it has been in focus across various industries, and how I3C adoption is defining the future of connected technology. 

Why We Need a New Serial Bus? 

The devices today are a lot smarter than what they used to be 10 years ago. An example is a smartphone, which may have a dozen or more sensors, such as motion, light, fingerprint, and temperature sensors, all of which are required to interact with the main processor simultaneously. 

Older serial communication protocols like I2C and SPI struggle with this. Some of the issues they encounter include the following: 

• I2C Limitations: Simple and common, but slow (standard mode 100 kbps to 3.4 Mbps). Additional wires, known as GPIO pins, are required when sensors want to alert the processor. Due to the large number of sensors, the wiring gets messy. 

• SPI Limitations: SPI is faster than I2C; however, each sensor requires a chip-select wire. Ten sensors imply 10 additional wires that are not very feasible when using them in small gadgets such as smartwatches or car systems. 

Moreover, I2C also relies on clock stretching, which may slow down communication in case more than one sensor is used. 

This is where the I3C protocol enters the picture. With growing I3C, devices can now be faster, use less power, and have many more sensors without intricate wiring. 

Curious how IoT devices and smart sensors stay connected so smoothly? Check out our latest blog, Future-Proofing OEM Devices in the IoT Era with Wi-Fi Easy Connect™. 

What is I3C? 

Let us begin with the fundamentals. “What is I3C?” 

I3C, full form for Improved Inter Integrated Circuit (I3C), is a protocol developed in order to address the drawbacks of the older serial protocols. 

I3C protocol is faster, smarter and less power-consuming, and it uses two wires: SDA and SCL. It is able to support numerous sensors simultaneously, and it can even communicate with older I2C devices. 

It is a communication standard developed by the MIPI Alliance to overcome the limits of older systems like I2C and SPI.  

Consider I3C communication protocol as an improved highway for data within your system. It enables smartphones, smartwatches, cars, and other gadgets to operate effectively without additional wires or complex designs. 

Key Features of I3C 

The MIPI I3C protocol comes with several smart features that make it perfect for modern devices: 

• Faster Data Rates: Sends information quickly, up to 12.5 Mbps or more in high speed modes. 

• Works with Older Devices: Offers backward compatibility and can be connected to older I2C devices without problems. 

• In-Band Interrupts: Devices can alert the processor without the need for extra wires. 

• Dynamic Addressing: Each device gets an address automatically, avoiding conflicts and manual setup. 

• Hot-Join: Devices can join or leave the system while it is running. 

• Low Power: It reduces overall power consumption, which makes it ideal for battery-powered devices. 

In short, MIPI I3C mixes the simplicity of I2C with the speed of SPI and adds smart features, making it ready for the next generation of gadgets. 

Core Advantages of I3C Protocol

How I3C Works 

The I3C protocol works using only two wires. One wire carries data (SDA), and the other controls timing (SCL).

At first, it looks just like the older I2C system, but the MIPI I3C version is much smarter as it makes communication between sensors and processors smooth and reliable.  

With an I3C interface, many devices on the same bus can communicate faster and with fewer wiring issues. It blends the simplicity of I2C with the speed you typically see in serial peripheral interfaces.   

Let’s now have a deeper look at how it works! 

A clear look at how the I3C main controller manages both I²C and I3C devices on the same bus.

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1. I3C Main Controller 

The I3C protocol follows a controller-target structure instead of the older master-slave system used in I2C. 

The controller is like the brain of the bus. It does several important jobs: 

• Starts and manages communication on the bus 

• Assigns unique addresses to each device 

• Controls the transfer of data 

• Manages how data is sent and received 

Without the main controller, the I3C bus cannot work. It keeps everything running smoothly, so all devices can share information without confusion. 

2. I3C Secondary Controller 

The I3C protocol can include more than one controller on the same bus. However, only one works as the main controller at a time. 

The secondary controller acts like a backup. It can take charge when needed, such as if the main controller fails or has to hand over control. 

Here’s what makes it useful: 

• Helps keep the system running without interruption 

• Improves reliability and flexibility 

• Allows smooth switching between controllers when needed 

This design makes the I3C bus stronger and more dependable in real-world applications. 

3. I3C Targets 

I3C Targets are the devices that connect to the I3C bus. The target devices can be sensors, memory chips, or other controllers that follow the I3C standards. 

Unlike older systems, these targets are not passive. Thanks to smart features like In-Band Interrupts (IBI) and Hot-Join, they can: 

• Send signals directly to the controller when needed 

• Join or leave the bus while it is still running 

• Communicate more actively instead of just waiting for commands 

This makes I3C Targets more responsive and efficient, allowing all connected devices to work together smoothly. 

4. Legacy I²C Targets 

One of the biggest advantages of the I3C protocol is its backward compatibility. This is because older I2C devices often rely on pull up resistors for proper signalling. 

This means older I2C devices can still connect to the same I3C bus and communicate without issues. 

Here’s why these matters: 

• Existing hardware can still be used 

• No need to replace older I2C components 

• Smooth communication between new and old devices 

This feature makes it easier for engineers and companies to adopt inter integrated circuit interface  without losing support for their current systems. 

In Short 

• The main controller sets the rules and manages communication.  

• The targets handle data exchange.  

• The secondary controller provides backup when needed. 

What makes this special is that even older I2C devices can still work on the same bus. 

Additionally, you get less wiring than SPI and faster performance than I2C, and this makes I3C both smart and efficient. 

Want to see how cutting-edge innovations are reshaping embedded and IoT systems? Explore our insights on software-defined embedded solutions for smarter IoT development. 

Why I3C Matters for the Future 

The pace of technology is faster than ever before. The watch, the car, the house gadgets, and our phones all rely on the existence of a multitude of miniature sensors that have to communicate with one another.

I2C and SPI, and other older systems that did this job have been doing so long enough that they are beginning to lag. 

At this point, I3C plays an important role. 

I3C will enable many sensors to cooperate on the same machine without reducing the speed. It transmits data at a higher speed, consumes less power, and the wiring is usually simple.

This assists the companies to create devices that are lighter, smarter, and longer lasting on battery. 

Think about smartwatches. It has sensors to measure your steps, heart rate, sleep pattern, and more. With I3C, all these sensors can share information smoothly without using extra wires or draining the battery too quickly.  

I3C would also be beneficial as more industries begin to adopt high-tech sensors such as cars, medical devices, and smart home devices. It makes all things intertwined in an effective manner. 

This is one of the reasons why I3C is regarded as a significant aspect of the future. It addresses actual issues and provides space for new approaches in most fields. 

Final Thoughts 

I3C controller is slowly becoming the new choice for smart devices. It keeps the simple two wire design of I2C but adds more speed, less power use, and easier communication. In this part, we learned why older protocols struggle and how I3C devices fix those problems with a cleaner and smarter system. 

We also saw how the controller, secondary controller, and target devices work together to keep everything running smoothly. These basics explain why more companies are now moving toward I3C specifications for modern designs. 

At ThinkPalm, we enjoy exploring new technologies that help businesses build better and more connected products. We look forward to sharing more insights as we continue exploring the next steps in smart and efficient device communication. 

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