1. ABSTRACT The goal of this project was to create a more realistic and interactive appliance interface for a Usability Science class here at Union. Usability Science deals with how easily a user can accomplish certain tasks and evaluating how usable certain designs are. The purpose is to replace the previous cardboard, ad-hoc interfaces with something that allows students to test their designs for usability more efficiently. The goal of our research was to design and create both the software and hardware implementations of a system that allows students to plug in any of many “widgets” (I/O devices) onto a main board in any location and then let the student specify in software how the widgets are supposed to interact with each other. Using a microcontroller, the board will also record when and how each widget was used so that the usability of a certain design can be determined. Designing the most modular and flexible way to create the hardware widgets along with an easy to use and modular programming language have been focal points of the project. The design has moved from connecting wires, I/O devices, and chips together on a protoboard, to prototype devices, to printed circuit boards with all the components in place and a programming language that allows a user to define a state machine for a design. A Pedagogical Tool for Usability Science Senior Project - Computer Engineering - 2009 Nickolas Potvin Advisors: Professors Hedrick, Cass, and Fernandes BACKGROUND Many of the design choices for this project were previously decided by another student so one of the main goals for us was to follow the designs already in place. The designs in place and future designs also have to coincide with the overall design goal to create a product that is modular and allows for a more usable simulation of an appliance. This means that all designs have to function in tandem with the microcontroller chosen for this project: the TINI by Dallas-Micro. The TINI is a Java enabled microcontroller that also has support for the 1-wire devices developed by the same company which are location independent due to their addressability. In addition, the TINI is Ethernet-enabled so all code updates and testing can be done through telnet or FTP. SOFTWARE DESIGN In order to design any software to use the TINI microcontroller and get these widgets to function, we had to explore the individual chip functions and use them in a Java program. The chips we used for this project are the DS2450 (A/D converter) for input and the DS2413 (2-channel switch) for output. Both chips have their own unique functions and every chip has a unique ID number used to identify it on the 1-wire bus. Each device’s ID number is stored in a database after I’ve created the widget using that device. After a user has created a program using my specific language created for this project, that program gets parsed into a tree, that tree gets broken down into a data structure, that data structure has specific values filled in from the database of known devices, and that data structure can then be used to fill in a template Java program to be used on the TINI. FUTURE WORK As of now, there are difficulties fitting some of the desired designs on to the given space requirements for each widget. Further research into the use of PIC chips is required in order to fit a clock (four 7-segment displays) or another complicated device onto one widget. The software also has much more work that needs to be done before it can be fully functional. In addition to storing information about each widget in a database, the program needs to save time-stamped data about each widget that is used while a program is running and be able to dump that data log at any point. The software also needs to easily allow each widget’s functionality to be tweaked for each user so that different boards can be designed. WIDGET CREATION The first picture here (left) shows one of the prototype widgets I have created that is a 7-segment display that uses four DS2413 chips. The second picture shows another finished widget made using printed circuit boards. This second widget (middle) uses a potentiometer to act as a knob and a DS2450 chip. Both widgets were created using a solder reflow process that involves a special solder paste and the use of an oven to solder small chips. This design can be easily reproduced and simply plugged into the main board, which can be seen below (right). This prototype board only allows four widgets to be plugged in simultaneously but has the exact same functionality of a larger final board. WIDGET DESIGN After we decided on the initial hardware design, we needed a more efficient way to create each widget. We were able to transfer the previous hardware design into CAD Eagle (top). After all the parts are on the schematic in Eagle it is a simple matter of making connections where they are needed. A board file is then created in Eagle, which specifies the exact locations of each part and wire (middle). Once we have finished the board file, it is exported to CircuitCAM, which allows us to prepare and convert the design for the circuit board printer. We can then use the circuit board printer to create the designed circuit using a collection of drilling and milling tools (bottom) on the LPKF rapid prototyping machine. The finished product (after quite a bit of soldering) can be seen in the “Widget Creation” section. RESULTS Not only have we created a design that allows the widgets to be location independent and interchangeable but we have also created several fully tested and implemented widgets. Two widgets have been fully tested and four have been designed. A prototype main board has also been created to allow the widgets to interact just as they would on a larger version. I have also made notable progress on a user scripting language that defines how widgets behave.