Universal Stylus Initiative

The Universal Stylus Initiative (USI) is a non-profit alliance of companies promoting a technical standard for interoperable active pen styluses on touchscreen devices such as phones, tablets, and computers.^[1][2][3]

It defines a two-way communication protocol between the stylus and the computer and allows the stylus to remember user preferences for ink color and stroke. It support 9-axis inertial measurement.^[4]

Products started coming to market in 2019 including one stylus and several Chromebooks from different manufacturers.^[1] By 2019, there were over 30 members, including Google and 3M, but some major players like Apple and Microsoft had not joined.^[4] As of 2022, the promoters include Google, Intel, Lenovo, Samsung, and Synaptics. Dell, Sharp, and Wacom are contributors.

While USI promotes itself as an open standard,^[5] access to detailed specifications is restricted to paying members.^[6]

History

USI was launched on April 23, 2015, by a group of prominent OEMs, stylus and touch controller manufacturers.

• September 22, 2016: Release of the USI 1.0 Stylus and Device Specification
• September 26, 2019: Announcement of the first 14 companies with products using the USI 1.0 Specification
• June 10, 2020: Launch of the USI active stylus certification program
• February 28, 2022: Release of USI Version 2.0 specification

Features

USI 1.0

1. Two-way communication protocol
2. Support for multiple simultaneous styluses on a single device
3. Pressure sensitivity (up to 2048 levels in USI 1.0)
4. Button presses and eraser functionality
5. Tilt detection
6. Supports a color palette of 256 colors

USI 2.0

1. NFC wireless charging capability
2. Support for in-cell display panels
3. Expanded tilt functionality
4. Enhanced color palette with 16 million colors.^[7]
5. Enhanced pressure sensitivity (up to 4096 levels)

Some reports suggests backwards-compatibility issues at least in some devices, with some USI 1.0 pens not working with screens that are certified USI 2.0 compatible.^[8]

Certification process

According to the USI website, the certification process is from an end-user perspective and is a test of performance and interoperability. The website guarantees that the certification program offers:

Personal experience: Users can choose a product in a form factor that works for their convenience and still get all the features and functionality.

Predictable experience: All USI products will perform the same way.

Interoperability: Ensures that the USI-certified styluses will work on all devices.

See also

• Stylus (computing)
• Digital pen
• Pen computing
• Active pen
• Wacom
• Surface Pen
• Apple Pencil
• Computer mouse
• Human–computer interaction