I2C Vs I3C | Difference between I2C and I3C interface bus types

This page compares I2C Vs I3C protocol and mentions difference between I2C and I3C interface bus types.

What is I2C interface

I2C was invented by Philips Semiconductor (Now NXP semiconductor) in 1982. It is a 2 wire (SDA, SCL) synchronous serial interface which is widely used to interface peripherals with processors and microcontrollers for short distance communication. Later many companies have introduced their products using compatible I2C specifications which include Texas Instruments, Nordic Semiconductor, STMicroelectronics, NEC, Siemens, Intersil etc.

I2C Interface Protocol

Initially I2C was limited to 100 Kbps operation. Later on, many different speed categories have been supported by I2C bus as mentioned in the following table.

Modes Data rate Bus Direction
Standard mode (Sm) Up to 100 Kbps Bidirectional
Fast mode (Fm) Up to 400 Kbps Bidirectional
Fast mode plus (Fm+) Up to 1 Mbps Bidirectional
High speed mode (Hs mode) Up to 3.4 Mbps Bidirectional
Ultra Fast mode (UFm) Up to 5 Mbps Unidirectional

Following are the features of I2C interface.
• Includes electrical and timing specifications and associated bus protocol
• Two wire interface implemented using SDA (Serial data) and SCL (Serial clock) lines
• Unique start and stop condition
• 7 bits are used by slave devices for addressing, can be extended to 10 bits as per specification
• Bi-directional data transfer is supported
• Acknowledgement is used after each transferred byte
• No fixed length of transfer

What is I3C interface

The I3C specifications was initially released in 2018 and later updated in 2021. I3C is the short form of Improved Inter Integrated Circuit which is a 2 wire digital interface similar to I2C. It provides improvements over I2C and SPI interfaces released earlier. I3C specifications are managed by MIPI Alliance Inc. I3C offers low power, low cost and fast digital interface. It supports multi master and multi-drop connectivities between host processors and peripheral devices such as sensors.

I3C Interface Protocol

Following are the features of I3C interface.
• 2-wire serial interface (using SDA and SCL) with up to 12.5 MHz using push pull configuration
• Legacy support for I2C devices on same bus
• Dynamic addressing used by I3C devices
• Supports static I2C addressing, I2C messaging, I2C single data rate messaging (SDR)
• Supports optional high data rate messaging modes (HDR)
• Supports multi-drop and multi-controller capabilities
• Supports In-Band interrupt
• Supports Hot-join

Difference between I2C and I3C

Following table compares I2C versus I3C interface types and mentions difference between I2C and I3C with respect to various parameters.

Parameters I2C interface I3C interface
In Band interrupt Not supported Supported
Effective Data Rate Lower (Max. 3 Mbps) Higher (Max. 33.3 Mbps)
Dynamic addressing Not supported Supported
Energy consumption Higher Lower
Hot joining Not supported Supported
Advantages and disadvantages I2C interface I3C interface

➨Also refer I2C versus I2S and difference between I2C vs SPI vs UART.

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