A Standard for Styluses
Although the advent of modern capacitive touchscreen devices, particularly the iPhone, resulted in styluses falling out of favor for a few years, this input device is still going strong. Styluses are seeing support on more devices than ever. After all, they offer a level of precision that is simply not possible with fingers.
You will primarily find two types of styluses on the market—active and passive. Passive styluses are basically a finger replacement. As a result, they work on most capacitive screen devices but aren’t very useful. On the other hand, active styluses are much more advanced and include features like pressure sensitivity, tilt support, and more. This is why they are restricted to devices that support their stylus protocol.
As a result, the active stylus market is fragmented. You can’t simply buy an excellent stylus and expect it to work on all your touchscreen devices, even though they might support stylus input.
However, USI or Universal Stylus Initiative is aiming to change this very problem. It is an industry group that develops and maintains an open standard for interoperable active styluses. It offers a standard signaling mechanism and communications protocol for styluses and touchscreen devices.
Any stylus compliant with this standard is known as a USI stylus. And it works with any touchscreen device that is USI-enabled, regardless of its platform, manufacturer, or form factor. So basically, whether you buy a USI stylus or it comes bundled with your device, it will work with any USI-enabled device.
Which Devices Support USI?
As of May 2022, USI technology is available on dozens of Chromebooks from Acer, Asus, CTL, HP, Lenovo, NEC, and Samsung. You can find a relatively current list of all USI-capable Chromebooks on the Chromium project website.
Similarly, dozens of USI styluses are available from Logitech, J5Create, HP, Lenovo, Penoval, and more.
Apart from Chromebooks, USI hasn’t been widely implemented on other devices. One of the reasons for this is the lack of support from Apple and Microsoft, as these two companies are responsible for some of the world’s biggest platforms.
The USI Specification
The USI 1.0 specification, which was the first release of the standard in 2016, included the essential active stylus features. It provided support for 256 colors, 4096 levels of pressure sensitivity, and nine-axis inertia measurement. But for almost six years, the USI specification didn’t see any changes. As a result, as of May 2022, you will only find styluses and devices with support for USI 1.0 on the market.
However, the next version of the specification—USI 2.0—was finally unveiled in February 2022. It brings several exciting but optional improvements to the specification. One of the highlights is wireless charging support using NFC. This means NFC-capable devices will be able to charge the USI styluses wirelessly, removing the need for AAAA batteries or awkward USB charging connectors.
Additionally, the USI 2.0 specification expands the color palette from 256 colors to over 16 million colors and improves the tilt functionality. Lastly, it brings support for in-cell displays.
In-cell is a technology found on some touchscreen displays that removes the layer of glass between the display stack and touch elements to make the overall screen thinner. Thanks to the in-cell display support, USI technology can be implemented on a broader range of devices.
The first devices and styluses with the USI 2.0 specification are expected to start rolling out in 2022.
Advantages Over Traditional Active Styluses
The USI standard brings several advantages over the traditional active styluses. Unlike the traditional active styluses, which only support one-way communication, stylus to device, USI supports two-way communication. So both stylus and the touchscreen device can talk to each other, enabling updating of parameters in the stylus from the device or loading of saved parameters from the stylus to the device.
For example, a USI stylus can remember your preference for ink color or stroke from one device and carry it over to another USI-compliant device.
USI also brings multi-pen support, which is similar to multi-touch on your phone. So USI-enabled screens can take simultaneous input from multiple styluses. This is particularly useful on large-screen products, such as interactive whiteboard displays.
In addition, USI styluses don’t need any pairing. You pick a USI pen, and it just works.
Do You Need a USI Stylus?
As of now, unless you own a Chromebook that supports the USI protocol, a USI stylus will be of little use to you. It doesn’t work on touchscreen devices that lack support for the USI protocol, such as iPads and Microsoft Surface devices.
Even though at the time of writing it’s been almost three years since the first USI styluses became available, the standard hasn’t seen much adoption beyond Chromebooks. And unless USI expands beyond Chromebooks, USI styluses will end up being a niche product, far from their hope of being universal styluses. Maybe you can affect change, though, by investing in a USI-compatible Chromebook.
