USB 2.0 as an integration standard for IoT products

Eric Huang worked on the world's first BIOS that supported USB keyboards and mice while at Award Software in 1995. He also worked at USB cores and software company inSilicon, which was acquired by Synopsys in 2002. He served as chairman of the USB On-The-Go Working Group for the USB Ipmplementers Forum from 2004-2006.

The excitement surrounding the Internet of Things (IoT) is spawning a small industry of design houses building IoT devices for niche applications, but lack the resources to create custom chips to do so. This has created an opportunity for SoC designers to build IoT platform chips that can be made in millions, to meet the requirements of foundry economics, yet are flexible enough to enable the IoT houses to differentiate their offerings in multiple markets.

Many IoT platform chip designers are now using the USB 2.0 interface specification and the USB Type-C connector as an integration standard for IoT designs at the board level, and for finished IoT designs at the systems level. The USB 2.0 interface offers the right mix of performance, flexibility, area, and power consumption to enable IoT platform chips that can quickly be adopted as the heart of a myriad of niche IoT products.

One way to look at the opportunity for IoT platform chips is to divide the IoT market into three broad categories: wearables, smart buildings, and smart cities. Almost all IoT devices are going to need some form of wireless or wired connectivity, the ability to interface to sensors and controls, some power management, and interfaces to the real world. Each of the broad IoT market categories will have additional common features, which will need to be supported in the hardware if the platform chip is going to succeed in that category.

USB is an attractive option for connectivity and controls because it’s easy to use to prototype an application by buying off-the-shelf chips and plugging them together. It should take just a few hours to prototype an IoT application by plugging together USB cameras, sensors and a Wi-Fi link.

Implementing USB in an IoT platform chip means that features can be added to an IoT product either by adding a chip to the system PCB, or by plugging in a USB peripheral. USB host drivers, which are widely available for Linux and other open-source operating systems, support either form of integration. This gives USB an advantage over interfaces such as I2C or PCIe, which need different drivers for each level of integration.

So far, USB 2.0 seems to be the preferred option for an IoT SoC integration standard. USB 3.0 at 5Gbit/s, and USB 3.1 at 10Gbit/s, are popular for new consumer products, but in many IoT applications, USB 2.0 running at 480 Mbit/s is fast enough. Choosing USB 2.0 also means that the interface’s active power consumption is about half that of a USB 3.0 implementation, while its die area is about one tenth that of USB 3.0. And there’s plenty of useful work that can be done at USB 2.0 speeds, such as interfacing with debuggers or updating firmware.

In addition to power, performance and area, IoT design houses are strongly focused on ease of use. If an IoT device is going to be used often, such as a charging cradle, then the ease with which a connection is made is obviously important. In addition, if an IoT device is going to be connected to infrequently, such as a thermostat monitor, then it makes sense to ensure that doing so is easy, due to the user’s lack of familiarity with it.

For this reason, we are seeing rising interest in implementing the USB Type-C connector within IoT applications. The Type-C connector makes USB easier to use, because it can be inserted either way up and still make a connection. Type-C is also more durable than most other forms of USB connection, because the connector’s reversibility evens out stress on the cable and the plug has been specified for more insertions. USB Type-C is also small, which is useful for devices such as wearables.

USB Type-C also supports power of up to 15W, twice that of previous USB connector standards, which enables either faster charging, or the use of more features in the IoT system at once.

The rise of the IoT is creating opportunities for small design houses to develop connected products that can serve niche application areas, if they can access IoT platform chips that have the right mix of features and flexibility. USB 2.0 and the Type-C connector provide an attractive option for such chips – enabling fast prototyping, straightforward software interfaces, and flexible integration strategies.

Further information

• Visit Synopsys DesignWare USB 2.0 Type-C IP for IoT
• Download DesignWare USB 2.0 Type-C IP for IoT Datasheet

Author

Eric Huang worked on USB at the beginning in 1995 with the world’s first BIOS that supported USB keyboards and mice while at Award Software. After a departure into embedded systems software for real-time operating systems, Huang returned to USB cores and software at inSilicon, the leading supplier of USB IP in the world. inSilicon was acquired by Synopsys in 2002. Huang served as Chairman of the USB On-The-Go Working Group for the USB Implementers Forum from 2004-2006.

Huang received an MBA from Santa Clara University and an MS in engineering from University of California Irvine, and a BS in engineering from the University of Minnesota. He is a licensed professional engineer in civil engineering in the State of California.

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