PCI Express Leads the Way in IoT Connectivity

您将学到什么：

在物联网空间中，高带宽，低延迟PCI Express（PCIE）互连的角色。
How PCIe architecture is used in IoT segments such as edge computing, test equipment, embedded/industrial PCs, and automotive.

物联网（IoT）代表跨越零售，制造，智能城市，能源和公用事业，运输，公共部门，教育，招待，健康和生命科学，汽车，银行，游戏和娱乐的广泛垂直市场实际上，我们生活的各个方面（图。1）。

物联网代表跨越边缘/网关的各种系统，数据采购设备，汽车，模块化计算机，工业PC等。下面的统计数据：

80 zettabytes (ZB) of data by 40+ billion IoT devices in 2025, accounting for more than half the data.¹
到2022年，数据中心以外处理的数据的50％。²
2023年，有43％的AI任务发生在边缘设备（vs.云）上。³
Annual business-to-business (B2B) IoT revenue more than US$300B.⁴

Most of that data will be processed, stored, and analyzed at the edge to help deliver better latency, conserve network bandwidth, and improve reliability, security, and privacy. As data growth explodes, high-bandwidth I/O capabilities along with AI will become necessary to transport and transform this data into actionable information and valuable insights. In this article, we will delve into the role played by PCI Express (PCIe) technology as the primary I/O interconnect in the IoT space.

PCIe architecture has provided I/O connectivity for computing platforms for more than three decades. This is due to the ability of PCIe technology to seamlessly deliver a cost-effective, HVM (high volume manufacturing) friendly, power-efficient, high-bandwidth, and low-latency solution through six generations of technology evolution, doubling the data rate every generation and having full backward compatibility with prior generations（图。2）。

Additional protocol enhancements such as precision time measurement (PTM), I/O virtualization, and security features like link encryption are essential in the IoT space. Even though a multitude of form factors (e.g., PXI, M.2, U.2, CEM, various flavors of small form factors) have evolved to meet the needs of diverse systems across the IoT compute continuum, they all use the same silicon ingredients based on a common PCIe base specification.

PCIE架构在物联网领域中无处不在的I/O互连的成功是由于它是开放的行业标准。它得到了强大的合规计划的支持，以确保不同公司制造的设备之间的无缝互操作性。

PCI-SIG, a consortium of more than 800 member companies spread across the globe, owns and manages PCI specifications and runs the compliance program. We expect PCIe technology to continue to evolve to meet the I/O needs of the IoT segments for many more years to come. Let’s take a closer look at how PCIe architecture is used in the following IoT segments: edge computing, test equipment, embedded/industrial PCs, and automotive.

边缘计算

边缘计算允许放置移动，存储和处理数据所需的资源，更接近数据源或服务交付点（（Fig. 3），迎合不同水平的服务质量（QoS）期望。

基于优化的位置，Edge Computing对于开发需要更快决策的新应用程序将是至关重要的。边缘计算是云计算的发展和扩展，以转换基础体系结构并为应用，服务和业务模型创新创建一个成熟的环境。

The PCIe specification, which is widely deployed in the data-center market, is thus uniquely positioned to accelerate the development of edge solutions. The three key performance indicators driving edge value proposition and how PCIe technology capabilities fit into this big picture include:

延迟和决定论：Advanced applications such as factory automation, robotics, industrial process control systems, video surveillance and security, immersive media applications, autonomous vehicles, and content delivery demand sub-milliseconds to tens of milliseconds of end-to-end latency and deterministic deadline-based response. A traditional cloud-based solution can’t meet this requirement.
Bandwidth:到2022年,82%的IP流量将视频内容。This traffic is expensive to transport to the cloud and process at a cloud data center. End users and service providers are motivated to process video data at the edge to lower latency, reduce jitter, improve video quality, and create new revenue with value-added services such as content delivery networks (CDNs), cloud gaming, or video analytics for enhanced retail experiences and smart-city applications.
Data locality and regulatory compliance:Data privacy and security are driving the need for broad edge deployments as governments implement policies to protect customer data and maintain data within their geographies, such as the General Data Protection Regulation (GDPR) in the EU.

PCIe architecture, being a high-bandwidth, low-latency and secure data-connectivity standard, is ideally suited for these applications.图4shows a simplified block diagram of an on-premises edge gateway and how PCIe technology provides the connectivity for the various subsystems within it.

Let’s look at this in detail:

每个业务都需要主动为网络故障转移计划，以进行无缝操作。可以使用Cellular 4G LTE/5G或有线解决方案（例如DSL，电缆或光纤连接）来实现广阔的网络连接，每种连接都通过PCIE连接。在此示例中，如果有线WAN连接下降，则可以通过故障转移到LTE/5G。
路由器可以根据Wi-Fi模块使用有线以太网或无线LAN提供多个LAN连接。例如，基于以太网的相机可以通过以太网开关连接到CPU，以进行数字监视和安全性（DSS）系统。无线外围设备（例如零售商店中的销售点（POS）系统）可以通过Wi-Fi模块连接。
Low data-rate wireless connections, such as a handheld bar-code scanner or a temperature and humidity sensor on the shelf in a retail store, can connect to the edge system via Bluetooth. To provide office automation, light bulbs, window shades, remote controls, etc. can communicate via Bluetooth, Zigbee, or Z-Wave wireless connectivity solutions.
DSS和网络录像机，医学成像系统等需要存储捕获的数据以进行进一步处理。快速，可靠和安全的存储对于物联网应用程序至关重要。高度与物理占地面积的比例以及能够承受严峻环境条件的能力，这也是一个重要的考虑因素，因为边缘设备安装在诸如石油炼油厂之类的室外苛刻环境中。

The NVM Express (NVMe) specification is an interconnect protocol used to access high-speed storage media. It’s designed to connect high-performance NAND flash memory to compute resources over native PCIe links. It’s a streamlined memory interface with 64K I/O queues, each supporting up to 64K I/O operations, eliminating the legacy SCSI command stack and direct-attached-storage (DAS) bottlenecks associated with traditional hard-drive interfaces. This results in a uniquely tuned I/O architecture optimized for solid-state media.
Storage at the edge needs the ability to support 24x7x365 ingestion of new data and must have enough extra bandwidth and I/O capacity to handle batch and ad hoc queries against this data. A PCIe-based host interface also provides NVMe SSDs with the high bandwidth needed to process this aggregated data at the edge into knowledge and convert it into actionable intelligence.

根据垂直市场，IoT网关支持许多旧版和I/O标准以及自定义I/O接口。由于通常使用相同的CPU设计来开发为多个市场服务以实现规模经济的边缘解决方案，因此PCIE技术提供了一种有效的方法来连接各种I/O控制器，以扩展和汇总这些接口。例如，在工业自动化市场中，工业以太网解决方案（例如Ethercat，以太网/IP，PROFINET，CC-LINK-IE和串行协议），例如CIP（常见工业协议），PROFIBUS，MODBUS等使用PCIE接口聚合器芯片。同样，建筑物自动化行业也使用用于建筑自动化和控制网络，KNX等的BACNET。
新兴应用程序（例如增强现实，深度感知和手势识别）需要多个图像传感器接口才能连接到应用程序处理器，而帧之间的延迟最小。MIPI到PCIE桥可以连接多个MIPI CSI图像传感器，并将数据汇总到PCIE输出。在工业部门，智能自动化系统捕获和处理视频，以构建安全性和质量控制。PCIE桥从HDMI，DVI或SDI接口捕获视频，并可以将完整的未压缩视频和音频传输到主机处理器以进行进一步处理。与视频输入相似的桥梁也可用于支持将LVD作为视频输出接口的相机。

Edge computing is seeing increased deployment of heterogeneous computing with the PCIe interconnect due to its low-latency, high-bandwidth load-store semantics. For example, the growth in data processing at the edge has led to the use of dedicated accelerators for artificial intelligence (AI), machine learning (ML) and deep-learning workloads. These PCIe-based accelerators perform parallel computation, leading to faster execution of AI workloads compared to traditional CPUs.

同样，视觉处理单元（VPU）有助于卸载视力工作负载，涉及多个具有较高框架速率的相机流，具有关键延迟关键处理要求。具有巨大并行计算潜力的图形处理单元（GPU）可用于视觉工作负载，以加速像素数据，数据挖掘以及其他AI和ML工作负载。

In applications where the algorithms and deep-learning neural networks are still evolving, reconfigurable field-programmable gate arrays (FPGAs) play a major role. Besides the acceleration functions, FPGAs provide many different connectivity options to connect to cameras, sensors, and other devices.

测验设备

数据采集是测量电或物理现象的过程，例如电压，电流，温度，压力或声音。从半导体设备验证到自动生产测试，仪器（PXI）系统的PCI扩展提供了具有专门定时和同步的其他I/O模块的高性能模块化仪器，以及用于测试和测量应用程序的关键软件功能。

PXI系统在结合坚固的模块化包装的同时，使用基于PC的PCI和PCI Express Technology。通过这种方法，可以满足高通道计算测试应用程序的定时，同步和吞吐量的要求。

测量精度是设计任何数据收购系统的最重要考虑因素。系统的总体性能，包括I/O采样率，吞吐量和延迟，是其他最佳考虑因素。PXI可以通过将新的PCIE标准纳入未来的产品中来满足不断增加的应用程序需求。⁵

嵌入/Industrial PCs

Industrial and embedded PCs (IPCs) are rugged PCs designed to operate continuously (24x7) in a harsh environment, including outdoor applications such as mining, agriculture, and energy distribution, and industrial applications like plant automation and process automation. They take advantage of the open PC architecture and deploy advanced video and AI technologies.

为了实现第四次工业革命的承诺，称为行业4.0，现代自动化系统已从专用的硬件转变为具有高可靠性，更多数据存储和更大计算能力的用户友好网络的PC。监督控制和数据进来（SCADA）系统和制造执行系统（MES）是此类系统的示例。

PCIe technology plays a key role in these PCs for storage, networking, accelerator attach, and even to connect to traditional automation systems using purpose-built hardware. It’s resulted in reduced capital costs (CapEx), increased efficiencies, and simplification of operations to lower operational costs (OpEx), leading to seamless convergence of operational technology (OT) and information technology (IT) infrastructure.⁶

Systems utilized for workload consolidation（图。5）are leveraging virtualization. Virtualization partitions the host platform into multiple software-defined, isolated environments with shared resources managed by a hypervisor.

Such a software-defined infrastructure has been made possible by advances in multicore CPUs, real-time operating systems (RTOS), lightweight hypervisors, and hardware-assisted virtualization technologies. I/O virtualization support in the PCIe specification has facilitated offloading of packet processing to network adapters, as well as direct assignment of virtual machines (VMs) to virtual functions, including disk I/O.

In control and automation systems, applications often are required to be synchronized across the network or devices within the subsystem to a common clock, with different levels of accuracy depending on the end usage. Ethernet time-sensitive-network (TSN)-based connectivity ensures synchronization between systems using the IEEE1588 and 802.1AS standards.

The PCIe specification’s Precision Time Measurement (PTM) protocol enables TSN network interface cards (NICs) or other peripherals to synchronize the network time to the CPU timestamp and ultimately to the software application. PTM minimizes the translation errors and thus increases the coordination of events across multiple components with very fine precision. Data from different sources, such as cameras, transducers, etc., can be reassembled in the host processor or accelerators through timestamps enabled by PTM to perform accurate analysis and take actions, even in safety-critical applications.

ipc提供更大的customization, reliability, and scalability, plus a longer product lifecycle. The wide range of systems include low-power and fanless designs in space-constrained environments, industrial panel-mounted PCs installed on surfaces, industrial rackmount PCs fastened to walls or in cabinets, industrial workstation PCs in closets, and embedded PCs in kiosks or medical equipment.

PCI工业计算机制造商集团（PICMG）开发的流行形式因子是COM Express。⁷将COM Express模块或标准SFF无线模块（如M.2）插入载体板的能力减少了开发产品的时间和成本。用户不需要了解与最新SOC相关的高速信号，RF设计和调整等相关的典型复杂细节。

This approach also streamlines the effort needed to get regulatory approvals such as FCC certification for the final product. Moreover, a modular design approach allows us to address the “mile wide and inch deep” IoT market by customizing the solutions based on common solutions driving economies of scale and wider adoption.

Automotive

十多年来，汽车电子设备的复杂性和复杂性一直在增长。⁸具有车载信息娱乐（IVI）系统，高级驾驶员辅助系统（ADAS）以及车辆到车辆（V2V）和车辆到所有设施（V2X）连接的现代汽车连通性，可以考虑到车轮上的数据中心，并考虑到车辆连接（V2X）（图。6）。To satisfy the consumer expectations for comfort and meet regulatory requirements for passenger and pedestrian safety, these systems are becoming prevalent in mass-market models and not just limited to luxury automobiles.

随着增加，存储和处理的数据量增加，诸如PCIE架构等数据中心技术在汽车电子系统中变得非常普遍，以连接强大的多货物CPU系统。除了PCIE连接的GPU，Wi-Fi，V2X和LTE/5G细胞模块，专业视觉和AI加速器ASIC，以太网NIC和FPGA在汽车电子控制单元（ECUS）中很常见。

正如预期的那样，该细分市场在极端条件下运行时具有非常严格的监管，安全性和可靠性要求，并期望可以替换大约15年的汽车使用寿命。PCIE技术具有高可靠性和可用性功能，是与包括相机，LIDAR，雷达以及超声和红外传感器的多个数据源接口的互连。它通过Wi-Fi，BT，LTE，5G和卫星为汽车提供无线连接。它也用于连接到存储设备和加速器（图。7）。

Conclusion

The PCIe interface is natively supported by most high-performance CPUs. In addition, the ecosystem includes a large range of available devices for AI/ML acceleration, networking, storage, and wireless connectivity. Availability of IP blocks, off-the-shelf standard form factor/modular components, debug tools, and a large ecosystem of developers familiar with the technology from the IT world is accelerating the penetration of PCIe architecture into IoT applications. Thetablesummarizes the key attributes of PCIe that drive optimal solutions in the IoT space.

With a rich and successful history of navigating several technology transitions in a backward-compatible manner spanning three decades, PCI-SIG is well-positioned to continue leading the evolving IoT landscape going forward. The power and promise of this open standards organization, backed by the combined innovation capability of 800+ member companies, makes the technology nimble, scalable, cost-effective, power-efficient, and multi-generational with relevance across all IoT segments and usage models for the foreseeable future.