Smartphone audio jack becomes multi-purpose, self-powered data port

May 28, 2014 // By Jean-Pierre Joosting
NXP Semiconductors has announced a versatile Smartphone Quick-Jack that simplifies connecting a variety of external devices to smartphones for self-powered data communications.

Adapting the standard 3.5 mm audio jack found on smartphones, the Smartphone Quick-Jack creates a universal interface for external sensors, switches, peripherals and other devices. Inspired by the University of Michigan's Project HiJack, it gives mobile, consumer and industrial product designers simple, plug-and-go connectivity for adding features to a variety of applications, from wearable medical and fitness devices, gaming controllers, and toys, to diagnostics and maintenance tools.

Many app features depend on connectivity with external devices to collect readings from sensors, control switches, data collected by external meters, as well as act on user inputs from keyboard, wands, or joysticks and more. For these types of apps, tying up the phone's high-bandwidth USB/Lightning port is unnecessary. While wireless connectivity offers user convenience; it can also increase BOM cost in small devices and requires experience working with wireless protocols, and an external power source. By repurposing the audio jack, the Smartphone Quick-Jack makes communication with external devices as easy as plugging in headphones.

"Smartphone user interfaces and connectivity features have revolutionized personal communication. The Smartphone Quick-Jack makes it exceptionally easy to take advantage of those same appealing features when designing end products, from something as sophisticated as a portable air-quality monitor, to something as rewarding as a child's toy with changeable/uploadable features," said Jim Trent, vice president and general manager, business line microcontrollers, NXP Semiconductors.

"We initially designed HiJack to create a universal way to connect low-cost sensor devices easily and securely to any brand of smartphone, tablet, or even PC," said Prabal Dutta, Assistant Professor, EECS , University of Michigan. "Today, the applications for audio jack connectivity have exploded, from our original vision of low-cost measurement instruments, to mobile entertainment, secure card readers, remote controls, personal medical monitors and many more."