// CMIS over I3C
Optical module management
moves to I3C.
As optical modules grow more capable, their management interface is migrating to I3C. The OIF is working on an upcoming revision to CMIS to introduce I3CMCI. Binho’s I3C tools are a natural fit for bringing up and validating that management plane.
// the specification
Module management, defined by the OIF.
The Common Management Interface Specification (CMIS) is the OIF Implementation Agreement for how a host manages a pluggable module, such as a QSFP-DD, OSFP, or COBO optical transceiver. Management operations run over a Management Communication Interface (MCI), reading and writing a memory map the module exposes for identity, configuration, control, and diagnostic monitoring.
The MCI has historically been the two-wire I2C-based variant, I2CMCI. As lane counts and module complexity rise toward 1.6T-class interconnect, the OIF is introducing an I3C-based variant, I3CMCI, bringing higher management speed, dynamic addressing, and in-band interrupts that replace dedicated interrupt pins. The memory map stays familiar; the interface underneath it gets faster and smarter.
// how it works
A host, the MCI, and the module.
The host walks the module’s CMIS memory map over the Management Communication Interface. Moving the MCI to I3C keeps the memory map intact while adding speed, dynamic addressing, and in-band interrupts.
// the host
The host
The host configures and monitors each module: it reads identity and capabilities, sets operating modes, and polls diagnostics, all as reads and writes to the module over the Management Communication Interface (MCI).
// the interface
The Management Communication Interface
CMIS carries management over an MCI. Historically that has been the two-wire I2C-based MCI (I2CMCI). The OIF is introducing an I3C-based variant, I3CMCI, bringing higher speed, dynamic addressing, and in-band interrupts in place of dedicated pins.
// the module
The CMIS memory map
CMIS defines the management memory a module exposes: a 256-byte addressable window, with 128-byte pages of a larger memory space switched into its upper half. The host walks that memory to bring the module up and keep it healthy.
// the operations
Monitor and control
Across that memory the host runs the full management lifecycle: discover identity and capabilities, configure and control the module, and continuously monitor diagnostics and telemetry. The same operations CMIS defines today, now over I3C.
// the tools
Bring it up. See the bus.
The Supernova drives the management bus as an I3C controller, or stands in as a target, so you can exercise CMIS register access before the silicon is final. The I3C Analyzer decodes the bus so you can see every transaction.
Hardware · USB Host Adapter
Binho Supernova
Drive the management bus.
The Supernova is a full I3C controller or target: bring up the bus, run dynamic addressing, read and write a module’s memory map, and handle in-band interrupts. Script it from a GUI, Python, or C.
- Controller or target on the I3C bus
- Register read/write, IBIs, dynamic addressing
- Scriptable from a GUI, Python, or C
Software · Saleae Plugin
I3C Protocol Analyzer Plugin
See every transaction.
The I3C Protocol Analyzer decodes the I3C traffic the management plane rides on, dynamic addressing, CCCs, and in-band interrupts, inside the Saleae Logic tool your team already uses.
- Decodes DAA, CCCs, IBI, and PEC
- SDR, HDR-DDR, and HDR-BT modes
- Runs in Saleae Logic 1.x and 2.x
// our edge
We know this bus.
CMIS is moving onto I3C, and I3C is the bus Binho has built its tools and its standards work around.
// standards
MIPI Contributor & OIF Member
Binho is a MIPI Alliance Contributor Member working on the I3C specification, and a member of the Optical Internetworking Forum, where CMIS is defined.
Semiconductor teams
200+ semiconductor companies use Binho tools to develop, validate, and ship devices with I3C support.
MIPI I3C Plugfests
We’ve verified our tools at the past 4 MIPI I3C Plugfests, and helped others verify theirs too.
// trusted by engineering teams at
+ hundreds more
// faq
Common questions.
What is CMIS over I3C?
CMIS, the Common Management Interface Specification, is the OIF Implementation Agreement for how a host manages a pluggable module such as a QSFP-DD or OSFP transceiver. It carries management over a Management Communication Interface (MCI). I3CMCI is the emerging I3C-based MCI, carrying that management over I3C instead of the legacy two-wire I2C-based MCI (I2CMCI).
Why is module management moving to I3C?
As lane counts and module complexity rise toward 1.6T-class interconnect, I3C brings higher management speed, dynamic addressing, and in-band interrupts that replace dedicated interrupt pins, while keeping the familiar CMIS memory map intact.
Is I3CMCI available now?
The OIF is working on an upcoming CMIS revision to introduce I3CMCI. Most deployed modules today still use the I2C-based MCI (I2CMCI); I3CMCI positions the ecosystem for the higher-speed, higher-density modules ahead.
Can I develop and test CMIS over I3C with Binho tools?
Yes. The Supernova acts as an I3C controller to bring up and exercise a module’s management bus, or as a target to stand in for one, and the I3C Protocol Analyzer decodes the I3C traffic the management plane rides on.
Explore the Supernova How does it relate to the other protocols over I3C?
CMIS over I3C is one of several higher-level protocols carried on I3C. It sits alongside MCTP over I3C for platform management, JESD300 SPD for DDR5 memory, and the MIPI I/Os over I3C Bridge, each defined by its own standards body and riding the same I3C bus.
Explore the I3C protocol