MIPI I3C is a serial communication interface specification that improves upon the features, performance, and power use of I²C, while maintaining backward compatibility for most devices.
This FAQ has been developed to introduce the MIPI I3C Specification [MIPI01] to developers and users. It answers questions raised to the MIPI Alliance Sensor Working Group (WG) after MIPI Board approval of I3C v1.0, or late in development of v1.0 after the technical freeze by the WG.
The Sensor WG has compiled these frequently asked questions (FAQs) to assist Member implementation activity. Some areas also include clarification when an area of the Specification was ambiguous, and this FAQ will show the intended resolution of the ambiguity. Many of these topics reflect areas of planned improvements for a future update to I3C v1.0, showing how a v1.0 implementation can be better prepared and/or compliant in advance.
None of the answers in this FAQ are intended to overwrite or overrule the information in the I3C Specification itself.
See also Section 2 in the MIPI I3C v1.0 Specification.
ACK: Short for “acknowledge” (an I3C bus operation)
Bus Available: I3C bus condition in which a device is able to initiate a transaction on the bus.
Bus Free: I3C bus condition after a STOP and before a START with a duration of at least tCAS.
Bus Idle: An extended duration of the Bus Free condition in which devices may attempt to Hot-Join the I3C Bus.
High-Keeper: A weak Pull-Up type Device used when SDA, and sometimes SCL, is in High-Z with respect to all Devices.
Hot-Join: Slaves that join the I3C bus after it is already started, whether because they were not powered previously or because they were physically inserted into the Bus. The Hot-Join mechanism allows the Slave to notify the Master that it is ready to get a dynamic address.
In-Band Interrupt (IBI): A method whereby a Slave device emits its Address into the arbitrated Address header on the I3C bus to notify the Master of an interrupt.
Main Master: Master that has overall control of the I3C bus.
Master: The I3C bus device that is controlling the bus.
Slave: An I3C Slave device can only respond to either Common or individual commands from a Master. A Slave device cannot generate a clock.
DisCo - Discovery and Configuration (family of MIPI Alliance interface Specifications)
e.g. - For example (Latin: exempli gratia)
i.e. - That is (Latin: id est)
See also the acronyms defined in the MIPI I3C v1.0 Specification.
CCC - Common Command Code (an I3C common command or its unique code number)
CTS - Conformance Test Suite
DAA - Dynamic Address Assignment (an I3C bus operation)
FAQ - Frequently Asked Questions
HCI - Host Controller Interface (a MIPI Alliance interface Specification [MIPI02])
HDR - High Data Rate (a set of I3C bus modes)
HDR-DDR - HDR Double Data Rate (an I3C bus mode)
HDR-TSP - HDR Ternary Symbol for Pure Bus (an I3C bus mode)
I3C - Improved Inter Integrated Circuit (a MIPI Alliance interface Specification [MIPI01])
IBHR - In-Band Hardware Reset (an expected I3C bus feature)
IBI - In-Band Interrupt (an I3C bus feature)
ODR - Output Data Rate
SCL - Serial Clock (an I3C bus line)
SDA - Serial Data (an I3C bus line)
SDR - Single Data Rate (an I3C bus mode)
SPI - Serial Peripheral Interface (an interface specification)
[MIPI01] MIPI Alliance Specification for I3CSM (Improved Inter Integrated Circuit), version 1.0, MIPI Alliance, Inc., MIPI Board adopted 31 December 2016.
[MIPI02] MIPI Alliance Specification for I3C Host Controller Interface (I3C HCISM), version 1.0, MIPI Alliance, Inc., In press.
[MIPI03] MIPI Alliance Specification for Discovery and Configuration (DisCoSM), version 1.0, MIPI Alliance, Inc., MIPI Board adopted 28 December 2016.
[MIPI04] MIPI Alliance DisCoSM Specification for I3CSM, version 1.0, MIPI Alliance, Inc., In press.
[MIPI05] MIPI Alliance Application Note for I3CSM, version 1.0, MIPI Alliance, Inc., In press.
[MIPI06] MIPI Alliance Specification for Camera Serial Interface 2 (CSI-2SM), version 2.1, MIPI Alliance, Inc., In press.
[MIPI07] MIPI Alliance Specification for Debug for I3CSM, version 1.0, MIPI Alliance, Inc., In press.
[MIPI08] MIPI Alliance Specification for Virtual GPIO Interface (VGISM), version 1.0, MIPI Alliance, Inc., In press.
[MIPI09] MIPI Alliance Conformance Test Suite (CTS) for I3CSM v1.0, CTS version 1.0, MIPI Alliance, Inc., In press.