WebClip: a connector for ubiquitous physical input and output for touch screen devices

It has become extremely easy for developers to build custom software for smartphone and tablet computers. However, it is still hard to extend those devices with external electronics, e.g. additional sensors and actuators. In the moment when external hardware can be easily attached to phones and tablets a wide new application space will be opened up. With WebClip we present a device offering digital and analogue I/O ports that can be controlled and monitored by just clipping the device onto a capacitive touch screen. A web page in the browser of the touch screen device is used to control the bi-directional communication. Data from the WebClip to the device is sent by emulating touches on the screen whereas the reverse direction uses light sensors on the bottom side of the clip to receive light sequences emitted by the web page. A simple Javascript API is offered to build custom web applications. We have successfully tested our prototype with a variety of phones and tablet computers and report on performance and limitations.