The Universal Stylus Initiative (USI) encourages touchscreen device makers and software developers to support a newly standardised peripheral interface. The USI standard (1.0) measures stylus user characteristics—like pressure, colour and stroke width—and communicates these to the tablet or smartphone host. The use of a standard interface, developers believe, will dramatically expand to use of stylus-dependent applications.

A consortium of computer hardware and software makers recently announced their support for a stylus peripheral standard. The Universal Stylus Initiative (USI 1.0) standard describes a handheld computer stylus interface, intended to work with any USI-enabled tablet or touchscreen. Supporters of the standard include computer industry heavyweights Dell, Lenovo, HP and Intel.

“Our goal was to have a single, universal stylus capable of operating with all the touchscreen devices that a consumer owns or uses in the workplace—whether tablet, 2-in-1 or smartphone,” said Peter Mueller, an Intel VP and chairman of the USI. “One USI stylus will talk to many different devices.” A stylus interface standard will increase the use of these peripherals, and expand the applications for them, Mueller believes.

The application of styluses with tablets has thus far been something of a niche. Many drivers may be familiar with the tablet-based forms filled out by service reps at an automobile service centre. Other use cases include drawing and graphics rendering—even handwriting recognition and analysis. Photo editing will be a major growth driver, suggests graphics industry analyst Jon Peddie of Jon Peddie Research. In these applications, the editor can use a stylus to highlight an object on screen with all the precision his hand will allow. The popularity of stylus applications like this could catapult the stylus market from 100 million units in 2015 to as much as 300 million in 2018, Peddie suggests.

The stylus, Jon Peddie reminds, is the latest computer peripheral device to get industry-wide attention—behind the keyboard, mouse, voice recognition hardware and touch pads. This is surprising considering that human beings learned to write with pens, long before they learned to work computers. What is miraculous, Peddie suggests, is that more than 30 companies got together on a new interface standard.

One stylus, many channels

In operation, the USI standard defines the communication method—the wireless protocol—by which the stylus sends data about its operation to the smart phone or tablet host. The data includes information such as pressure levels, stroke width or colour (selectable with button presses on the pen) or eraser operation. The USI technology makes use of the existing touch sensor (capacitance changes) in smart phones, tablets and notebook PCs, minimising the cost of a new peripheral.

The communications protocol, used to identify peripherals to the USI host, is fast and flexible, says Peter Mueller. Like wireless Ethernet, transmitter will seek the carrier frequency which ensures the best communication for any particular setting.

USI system Figure 1: USI System comprises of a USI-compatible touch controller and stylus. It defines the communication between an active stylus and a touch controller. (Source: Universal Stylus Initiative)

Areas standardised by USI members include the stylus discovery mechanism, the packet formats required to communicate key information (such as pressure, button info) and mechanisms for vendor extensions. Areas not specified by the standard include the stylus’ industrial design (its look-and-feel), the hardware/firmware implementation in the touch controller and the software APIs for stylus data access. The standard offers many avenues for vendor differentiation (see Table).

USI standard differentation

In addition to Intel, HP, and Dell, electronics industry notables supporting the Initiative include Sharp, Asus, LG and Lenovo. Touch controller makers include Parade Technologies, Silicon Integrated Systems, Raydium Semiconductor and STMicroelectronics. Touch pen makers include Wacom, Atmel, and Synaptics, among others. This group has enough momentum, Peter Mueller suggests, to bring USI products to market by the end of next year, or the beginning of 2018.

Influential suppliers on the sidelines regarding USI include Apple, who typically uses proprietary solutions for their product appeal, and Microsoft, which has investment proprietary pens for its Surface Pro computers.