37.1.1 Terminology and Abbreviations

The I3C communication protocol terminologies and abbreviations used throughout this document have been adapted from the MIPI I3C Specification v1.1.1 and can be found in the tables below.

Table 37-1. I3C® Bus Terminology and Definitions
TermDefinition
Active ControllerThe Controller device that is currently in control of the I3C bus
Address HeaderA data sequence on the bus that follows a Start or Restart and includes 7 Address bits, one R/W bit, and one ACK/NACK bit
ArbitrationA method used to determine which device has bus control if multiple devices started transmitting at the same time. It can also be required during Target transmission if a Controller addresses multiple Targets.
BroadcastA command or message intended for multiple Target devices and uses the Broadcast Address 7’h7E
Broadcast AddressA reserved 7-bit address transmitted by the Controller with the value of 7’h7E as part of a Broadcast message (see “Broadcast”)
Common Command Code (CCC)Globally supported standardized commands that the Controller can transmit either directly to a specific target (Direct CCC) or broadcast to all targets on the bus simultaneously (Broadcast CCC)
ControllerA device which has control over the I3C bus (timing and data)
Data WordA data sequence, typically occurring after the Address Header, for transmitting data on the bus and includes nine consecutive bits consisting of 8-bits of data and one T-bit
Defining ByteAdditional byte to further describe the configuration of a CCC
DeviceEither a Controller or Target
Dynamic AddressA device address assigned to the Target by the Active Controller during the initialization of the bus or the Target device; typically happens after power up
FrameA data transfer sequence starting with a Start and ending with a Stop
High Data Rate (HDR)A data transfer that occurs using both edges of the clock to achieve higher speeds
Hot-JoinA feature which allows a Target device to join the I3C bus after the bus has been configured and to notify the Controller device that it is ready to receive a Dynamic Address
I3C® Bus (or Bus)The physical and logical implementation of the Serial Data (SDA) and Serial Clock (SCL)
In-Band Interrupt (IBI)A method where a Target device generates an interrupt for the Controller to service using the I3C bus (without using any external interrupt lines)
Legacy I2C TargetA Target device that meets the requirements of the I2C Specification
Legacy I2C transactionA typical I2C transaction that occurs on the I3C bus
MessageA communication packet between devices on the bus
Offline CapableA device capable of disconnecting from the I3C bus physically or capable of ignoring I3C traffic on the bus
Open-DrainA High Impedance state of an output driver with an active pull-down and typically used with a passive pull-up; used for signaling of I2C communication and some I3C communication
Pad BufferAn I/O buffer available on the SDA and SCL pads that meets the voltage and speed requirements for the desired communication type (like I3C, I2C, SMBus)
PeripheralAnother way of referring to this Target Module
Primary ControllerThe Controller-capable I3C device that initializes the I3C bus and performs configuration of all target devices. It acts as the authority for the bus in its initial state and becomes the first Active Controller once the bus is configured.
Private TransactionA transaction that happens exclusively between the Controller and the Target that is not a CCC, IBI, or Hot-Join transaction
Push-PullAn output driver with active pull-down and active pull-up; primary method of signaling for I3C communication
RestartA signal that looks identical to a Start and can be used as an alternative to a Stop to be able to send multiple messages in the same frame
Secondary ControllerA Controller-capable I3C device that initially acts as a Target, but can accept Controller-ship from the Active Controller and become the new Active Controller
SignalingA method of pulling the SDA and SCL lines high or low to transmit data on the bus, see “Open-Drain” or “Push-Pull”
Single Data Rate (SDR)Data transfer that occurs using only one edge of the clock
Speed-LimitedA device that is unable to meet one or more timing requirements as per the I3C Specification
Spike FilterA filter that removes spikes shorter than 50 ns on the bus
StartA signal asserted by the Controller that is a high-to-low transition on the SDA line while the SCL line is at a constant high; used to signify the beginning of a new frame or message
Static AddressA device address that is fixed and cannot be changed
StopA signal asserted by the Controller that is a low-to-high transition on the SDA line while the SCL line is at a constant high; used to signify the end of a frame or message
TargetA device that can only respond to a command or message from a Controller device and cannot generate clock pulses
Table 37-2. I3C® Abbreviations
AbbreviationFull Name
ACKAcknowledge
CCCCommon Command Code
DMADirect Memory Access
FIFOFirst-In First-Out
GPIOGeneral Purpose I/O
HDRHigh Data Rate
HJHot-Join
I2CInter-Integrated Circuit
I3C®Improved Inter-Integrated Circuit
IBIIn-Band Interrupt
LVLow-Voltage
MVIOMulti-Voltage I/O
NACKNot-Acknowledge
PStop
PPSPeripheral Pin Select
RRead
R/WRead/Write
SStart
SrRestart
SCLSerial Clock Line
SDASerial Data Line
SDRSingle Data Rate
STSchmitt Trigger
T (or T-bit)Transition Bit
TTLTransistor-Transistor Logic
WWrite