A Question on I2C Device in a Mixed I3C Bus

JC1985 · ‎2024-04-03

Hi, STM Experts,

Recently, we are investigating if STM-H5 MCU with I3C SDR support could meet our system requirement. We now have a following question, and hope get support from you.

In our system, there will be not only I3C devices but also I2C legacy devices which can work at 400Kbps or 1Mbps modes. As for legacy I2C protocol, mutli-master feature is supported so that any of the I2C device can start a communication transaction when a bus is in an idle state. Is this still true for an I2C device working on a mixed I3C bus i.e. the I2C device (target in I3C specification term) can start a communication transaction when the mixed I3C bus is in Bus Availiable State? Will STM-H5 MCU support such a use senario?

Thanks and Regards!

// JC1985

Foued_KH · ‎2024-04-04

Hello @JC1985 ,

Yes, you can use I2C devices on I3C bus but only I2C targets.
some details are in this Application Note : - Section 9.10 Mixed communication : Introduction to I3C for STM32 MCUs - Application note
Also you can check the available examples in the STM32Cube FW :
STM32Cube_FW_H5_V1.2.0\Projects\NUCLEO-H503RB\Examples\I3C

Let me know
Foued

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Foued_KH · ‎2024-04-04

Hello @JC1985 ,

Yes, you can use I2C devices on I3C bus but only I2C targets.
some details are in this Application Note : - Section 9.10 Mixed communication : Introduction to I3C for STM32 MCUs - Application note
Also you can check the available examples in the STM32Cube FW :
STM32Cube_FW_H5_V1.2.0\Projects\NUCLEO-H503RB\Examples\I3C

Let me know
Foued

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

JC1985 · ‎2024-04-08

Thanks Foued, that answers my question clearly!