The Improved Inter-Integrated Circuit (I3C) is a simple and cost-efficient bidirectional 2-wire synchronous serial bus protocol developed by the Mobile Industry Processor Interface (MIPI) Alliance.
I3C is backward compatible with legacy Inter-Integrated Circuit (I2C) devices. Moreover, it provides the in-band interrupt (IBI) function and supports hot-join of I3C devices. This eliminates the need for adding an extra interrupt line to implement interrupts in I2C.
The I2C device, I3C slave device, and I3C secondary master device can coexist on the I3C bus.
The I3C APIs provide a set of common functions for I3C transfer, including:
- Opening and closing an I3C controller.
- Obtaining and setting I3C controller parameters.
- Performing customized I3C message transfer by using a message array.
- Requesting and releasing an IBI.
- Opening and closing an I3C controller.
- Obtaining and setting I3C controller parameters.
- Performing customized I3C message transfer by using a message array.
- Requesting and releasing an IBI.
[Figure 1](#fig1) shows the I3C physical connection.
>- The device address in the **I3cMsg** structure does not contain the read/write flag bit. The read/write information is passed by the read/write control bit in the member variable **flags**.
>- The **I3cTransfer()** function does not limit the number of message structures or the length of data in each message structure. The I3C controller determines these two parameters.
>- Using **I3cTransfer()** may cause the system to sleep. Do not call it in the interrupt context.
