Demo Time Slots: Authors: Gabriel Kopin Eugene Kozorovitsky Advisor: Dr. Rahul Mangharman Contributors: Sidharrth Deliwala ESE 441/442 Senior Design 2007 – 2008 Group # 5 Abstract Hardware Process ` Although the exact future of the iLED Wall here at the University of Pennsylvania is not entirely clear, the researchers and advisors believe that an expansive unit will be installed in the 2nd floor South GRW hallway. That system will perform in a manner quite similar to that of the iLED prototype, however, it will be much larger and therefore require drastically more computing power. The researchers believe that the control architecture of the expanded iLED Wall will incorporate either a complex FPGA or master-slave combination of smaller micro-controllers like the Motorola HC11. FPGAs, in the researcher’s opinion, are the method of choice due to the high number of digital input/output ports that allow the control system to eliminate the need for control line multiplexing and decoding. Also, having the ability to communicate with subsequent sections of an iLED Wall could prove vital to the seamless operation of the system. For example, as a user interacts with parallel wall panels, the control system must be able to fluidly transmit the detail of that interaction to parallel control systems. In this sense, a communication infrastructure might need to be developed. The researchers offer that the simplest way to do this is via a parallel communication port, such as RS-232. Lastly, more advanced iLED Walls will have the opportunity to interact with users in numerous ways. For example, one addition might be the inclusion of microphones behind panels that can react to speech directed towards the panel. Also, accelerometers might be used on a more compact, handheld unit to offer users the ability to interact with the iLED Wall through motion. Future iLED System Implementation Dual iLED Wall Display Hardware Diagram Stage 1 - Traditional LED configuration: Current flows from anode (+) to cathode (-) illuminating the LED Stage 2 - Reversed LED configuration: Current flows from cathode (-) to anode (+) initiating the LED’s photo- sensitive properties Stage 3 – Effective Capacitance LED configuration: Implied capacitor charged allowing leakage current to flow to the grounded anode (+) changing the logic level at the input port Software Process iLED Wall Demo Date: April 24 th, 2008 Demo Times: 9:00 – 9:30am2:00 – 2:30pm 9:30 – 10:00am2:30 – 3:00pm 10:00 – 10:30am There is a large amount of research today which involves real sensor networks with hundreds of nodes. It is very difficult to "see" and track what is going on at each node, which impedes the scientific progression. A solution to this problem is a programmable interface with interactive sensors which can be used as a generic visualization system for large data sets. The system could be used to simulate the sensor network routing schemes and see how the data disseminates across thousands of nodes, display which nodes are getting too much traffic, which have dying batteries, etc. The goal is to create an LED array programmed to visualize a set of data and respond to changes in sensor inputs – initially touch and, in a future implementation, sound and motion. When a typical light emitting diode (LED) is forward- biased light is emitted. When the voltage difference across the poles is reversed, so that the high voltage is at the cathode and low voltage at the anode, it is reverse-biased and no light is generated. Meanwhile, LEDs act as normal diodes in that a small leakage current is produced across the diode junction when it is connected in reverse. In fact, the leakage current is directly proportional to the amount of incident light on the LED. By measuring the time the internal capacitance takes to discharge (i.e. change from a HIGH to LOW logic state) we can determine the extent of a user's interaction with a particular LED or region of LEDs. Through the precise measurement of incident light, the generic visualization system is implemented as a touch-sensitize LED panel. By integrating multiple LED panels together a future implementation will be to implement an array of these LED panels to form the Interactive LED (iLED) Wall. iLED can then be used as a visualization tool for engineering research and boundless other applications – educational tool, games, or even as an aesthetic enhancement. Abstract Typical LED Photosensitive Properties