您将学到什么：
- How MIPI I3C relates to I2C。
- How MIPI I3C Basic compares to the full I3C specification.
- 今天如何使用MIPI I3C。
MIPI I3C, designed as the successor to the hugely popular I2C interface, is the MIPI Alliance's lightweight interface for easily and cost-efficiently connecting peripherals such as sensors, actuators, controls, and simple UI components to application processors. Products for these processors range from smartphones to wearables to systems in automobiles and server environments.
I3C comes in two flavors: the full I3C specification, available to MIPI Alliance members, and the royalty-free I3C Basic version, which supports all of full I3C specification’s core functionality and is publicly available for download.
完整的更新版本I3C and I3C Basic specifications于2021年9月发行。MIPI I3C Working Group, answers the most frequently asked questions about the I3C interface.
How is MIPI I3C related to I2C，与我相比，I3C有什么好处2C？
MIPI I3C was designed as the direct successor to I2C。Although I2C has been widely implemented, it's now more than 35 years old, and recent trends have posed new challenges for it. Data bandwidth requirements are on the rise, miniaturization is more and more necessary, and devices require even lower power consumption than before. MIPI I3C was developed specifically to address these issues while maintaining backward compatibility with I2C to support mixed use of I2C and I3C components within a device（图。1）。
Put simply, I3C is faster, requires fewer pins and wires, and uses less power than I2C。For example, I3C supports a standard raw data rate of up to 12.5 Mb/s with 12.5-MHz clock using single-data-rate (SDR) mode. All of these features help improve the wide variety of devices that can utilize I3C.
They’re especially useful for products like next-generation Industrial Internet of Things (IIoT) devices. Common requirements for such devices include the need to connect many peripheral components (sensors, touchscreens, etc.), very low power consumption, and compact design, all of which are facilitated by fewer pins and wires.
How does I3C Basic compare with the full I3C specification?
MIPI I3C基本旨在促进界面的访问和采用。因为我2C在各种各样的设备中的使用中，我们看到了对I3C版本的需求，该版本可以在MIPI的无版许可环境下广泛实施。虽然不完全相同，但I3C和I3C基本非常相似，因为I3C基本捆绑包是I3C最常用的功能。
在规格的最新版本中，我们通过将整个i3C规范中的许多功能带入I3C基本的许多功能，从而进一步减少了它们之间的差异。例如，I3C基本中的两种新的高数据速率（HDR）模式可以使用不同的时钟和数据传输模型，因此我们现在可以将原始数据吞吐量最多增加到25 MB/s（使用12.5-MHz使用HDR-DDR模式的时钟）在单车道上。那是一个巨大的飞跃。
I3C支持的主要功能是什么？
I3C提供了一种经济高效，简单且灵活的两线接口，旨在平衡更高数据速度的需求与功率效率（图2）。它利用CMO（互补的金属氧化物半导体）I/O，并最大程度地减少PIN计数和组件之间的信号路径数量。
In addition, I3C supports a data rate of up to 12.5 Mb/s using its simplest mode of operation, and it includes options for higher-performance, high-data-rate modes that can provide speeds in excess of 30 Mb/s in single-lane mode. It consumes low amounts of energy per bit transported, allowing for these high speeds without sacrificing a low-power design（图3）。For example, high-speed batch data transfers contribute to minimizing power consumption, as does allowing components to send infrequent bursts of data.
I3C支持频段间隔（IBIS），以消除对中断信号的其他物理车道的需求。一些较新的功能包括可扩展使用额外的公交车道的选项，以支持双通道或四轮型配置，最多可容纳单个车道的速度提高，以实现未来的界面，以实现即将出现的更高速度要求。
On top of that, a feature for standardized target reset enables better recovery from error conditions. This feature refines the specification’s ability to reset peripheral devices. It supports different levels of reset, from resetting only an I3C peripheral within a target to resetting the whole target device. This precision facilitates better recovery from error conditions by allowing a controller to reset only the selected targets without resetting any others.
设计师可以了解更多有关I3C和I3C基本的信息，以及他们的功能如何通过访问来比较以及访问规格the MIPI Alliance website。For instance, with the release of versions 1.1.1 of the specifications, we've updated our常见问题解答and released two new application notes—one on I3C’s热加入功能一个关于整合的virtual devices and targets。
Where is I3C being used today?
I3C Basic has already been adopted by JEDEC in itsSideband BusandDDR5standards. The MIPI Alliance also is actively working withDMTF（分布式管理工作组），ETSI(European Telecommunications Standards Institute), andTCA（值得信赖的连接联盟）。
我们希望促进许多不同组织之间的合作，以继续使I3C与更广泛的行业的需求保持一致，并且与令人难以置信的组织的这些合作正在帮助我们实现这一目标。另外，只要另一个组织采用I3C基本，它就会产生更丰富的生态系统，并在更广泛的行业中培养更多的互操作性。
Further, I3C can be used as a command-and-control interface for MIPI CSI-2 image sensors using the MIPI CCI (Camera Control Interface). Or, in the newest version of CSI-2 (v4.0 released to members in December 2021), it can be used as the principal transport channel for a camera sensor, negating the need for a physical-layer interface.
Use of CSI-2 over I3C leverages a new feature in the CSI-2 specification called AOSC (Always-On Sentinel Conduit), which enables ultra-low-power, always-on vision inferencing by an integrated or external digital signal processor. In turn, this allows a low-power host device to be always on, always monitoring its surrounding environment and waking the application CPU only when a relevant event happens. AOSC enables MIPI CSI-2 frame transport and bidirectional control using I3C.
除此之外I3C的MIPI调试specification developed by the MIPI Debug Working Group uses I3C to transport debug controls and data between a debug and test system and a target system. I3C also is used in the MIPI Touch family of specifications.
有哪些软件工具可以帮助支持I3C的实现？
MIPI在使用I3C时创建了几种不同的工具来帮助您，无论是完整版本还是I3C Basic。首先，有MIPI I3C主机控制器接口(I3C HCI), which defines a common set of capabilities for the host controller and the software interface. We’ve also developed anI3C HCI driver for Linuxand released it to the open-source community. And there’sI3C的MIPI发现和配置（MIPI Disco）, which is a software framework designed to simplify the software integration of peripheral devices that use I3C.
如何确保MIPI I3C实现之间的互操作性？
The first method is to use MIPI’s standardI3C conformance test suite, which is designed to ensure interoperability and compatibility between different vendors’ implementations. The test suite also is publicly available on the MIPI website.
MIPI I3C HCI在这方面也是一个巨大的帮助。使用I3C HCI，应用程序处理器供应商获得了连接到I3C的一致方法，从而消除了对产品特定于产品的i3C驱动程序的需求。取而代之的是，供应商，开发人员和分销商可以提供跨硬件平台可移植的通用i3C驱动程序。
It includes several optimizations based on typical usage and allows for vendor-specific extensions and optimizations. This also helps to control cost and complexity, freeing designers to focus their efforts on developing applications instead of interfaces. In addition, it broadens the scope of I3C implementation, since I3C HCI makes it easier for vendors and developers to integrate support for I3C for applications that are more than simple sensor devices.
The availability of the I3C HCI driver in the Linux kernel is of similar benefit. By defining device-specific operations for compliant I3C host controller hardware implementations from multiple vendors, the driver simplifies integration of I3C-based components for the global Linux developer community. The driver has been available in the Linux upstream source distribution since version 5.11 of the kernel.
Also, I3C Basic intellectual property (IP) is already available from multiple vendors, as are I3C conformance testing and verification IP test suites.
