Preliminary Design Report. Project Title: Interactive Electronic Hopscotch Board Team Name: Team Recess (Lose the Chalk)

Transcription

1 EEL 4924 Electrical Engineering Design (Senior Design) Preliminary Design Report 27 January 2009 Project Title: Interactive Electronic Hopscotch Board Team Name: Team Recess (Lose the Chalk) Team Members: Name: Karine Hoffman Phone: Name: Joe Gillespie Phone: Project Abstract: Our project will be the design of an interactive electronic hopscotch court that possesses the ability to change the layout of the court based on user input. The board will change its layout by lighting up various sections of the board in differing colors. The board will also detect whether the user landed on the correct part of the court and provide a visual and auditory feedback. Furthermore, the court will also be able to handle multiple players and declare a winner when one person makes a mistake.

2 Page 2/8 Table of Contents Item Page Introduction Technical Objectives Technical Concepts Cost of Equipment Division of Labor

3 Page 3/8 List of Figures and Tables Item Page Figure Figure Figure Figure Figure Figure Figure Figure Figure Table Table

4 Page 4/8 Introduction: Interactive Digital Hopscotch can be categorized as an electronic toy. This game board simulates the outdoor version by bringing it inside, making it safer and more contemporary. The rules of the game are traditional but by integrating technology it increases the excitement and competition level. Currently, other indoor mat versions of hopscotch exist but none are digital. Our concept will combine the fun level of the foot piano from the movie BIG and the timeless game of hopscotch. Figure 2 and 3 help explain the rules we are using for the game along with the basic design of the board. The main difference in rules from the standard hopscotch is that instead of a rock being thrown onto the board, we are instead using a sensor at the beginning. When the sensor is hit, lights run up and down the board and when hit again, they stop on a certain square. On the way to the finish, they must skip the square, and on their way back, the player must hit the square with their hand. Technical Objectives: The main objective is to have the Hopscotch board react to players. In order to create a portable and flexible game board, the pressure sensors and LEDs chosen must be flexible and able to withstand bodily forces. We will need to interface a series of pressure sensors with a microprocessor that will maintain gameplay using LEDs and sounds. Multicolored LEDs will enhance the board and provide direction for gameplay. Basic hopscotch rules that our gameplay will follow are attached at the end of this document. The microprocessor will connect to an LCD and user interface buttons to select 1 or 2 players. We would also like to be able to create an alterable game board allowing the user to play on different hopscotch courts. This will be achieved by using LEDs to highlight the sensors and a random select on start up to determine the court shape. Another possible objective will be to create the connection from the court to the microprocessor/lcd/power console to increase portability without damaging the brains of the hopscotch game. Figure 1 Basic Wiring Diagram

5 Page 5/8 Figure 2 - Game Rules Figure 3 Sensor layout/basic court

6 Page 6/8 Technical Concepts Though the concepts behind the system are fairly straight forward, connecting and creating a user friendly system that fits within a reasonable cost constraint is a tough challenge. While planning the implementation of our idea, we have run into a few major technical decisions to make as to how to accomplish our goals. First, what kind of pressure sensor we can use to detect whether the player managed to land in the right location. Secondly, what type of LEDs we will use to light up our board to display the locations to jump and for decorations. Next, we needed to decide what kind of flexible material to use for creating the mat, and finally, what kind of microcontroller we need to use. First, we needed to decide on the type of pressure sensor we wanted. At first glance, the main type of pressure sensor consisted of large, inflexible, and expensive pressure sensors geared toward industrial purposes. However, after some deeper searching, we found items such as force sensitive resistors and soft membrane potentiometers. The force sensitive resistors (FSR) act as an adjustable resistance that alters based on the force being applied. There seemed to be two main companies that produced them, Interlink (Figure 4) and Figure 4 Interlink Tekscan, with the Flexiforce line (Figure 5). The soft membrane potentiometers are devices that will linearly alter their resistance based on where on the strip the force is applied (Figure 6). Using the FSRs, we are able to set them around the mat, and by using an operational amplifier as a comparator or by using dedicated comparator chips, we may utilize the FSR as a switch (Figure 7). This Figure 5 Flexiforce allows us to use the standard I/O pins on the microcontroller instead of the A/D ports. However, we may reduce the area one is able to step on for the game. Alternatively, we may be able to use the potentiometers to detect a wider range of where the player is stepping. Unfortunately, the longest potentiometers are 500 mm long. They are also more expensive and each potentiometer requires the use of an A/D pin while still not guaranteeing that the player will step. Between the two types of FSRs, the Flexiforce seems like a better choice due to its flexible Figure 6 Potentiometer design that allows the resistor to be bent in any pattern. However, this line has a smaller sensor size and is almost twice the cost of the 1.5 sensors from Tekscan. From our initial pricing, the 1.5 square FSRs will cost about nine dollars apiece. By using these FSRs, we can arrange them in a grid with about three per row. This will allow us to use either two squares side by side or a single sensor in the middle. Using these and selecting which we want to receive data from, we can create a large amount of possible combinations for the board. Figure 7 Comparator

7 Page 7/8 For the lights for our mat, we decided to go with a variety of decorative LED lighting. We have two light systems, one set of lights surrounding each of the sensors and another that is a simple strip that will light up sequentially down the middle of the board. When we start the game, we wanted the lights around the sensors to cycle through colors along with some music. Thus, we decided upon RGB LEDs. These allow us to change the colors without having multiple LEDs. Then, for the lights running down the middle of the board, we can simply use plain LEDs with a variety of colors. By looking at Figure 8 RGB LED websites, we estimate the RGB LEDs will cost about two dollars apiece. We do however have a large amount of normal LEDs that we can use for the other light array at no cost though we may need to buy more at about 35 cents apiece. We also need a flexible mat for the game board. It is imperative that the mat is durable and semitransparent so that an LED light can shine through. We are planning on using the same sort of rubberized plastic used in other game mats. Lastly, we needed to decide on what type of microcontroller is needed. We decided that due to its good software support and the large variety of chips, we would use an Atmel chip. We also discussed the PIC chips by microchip. Though the PICs are most likely capable of doing what we needed, we decided to use the Atmel chips because of their greater flexibility. We may also need a large number of pins on the microcontroller so we will most likely be using an Atmega640 or similar unless we can find a method to reduce the number of pins needed.

8 Page 8/8 Cost of Equipment Cost Objectives Part Unit(s) Cost/Unit Total Cost Force Sensor Atmel MicroP LEDs Speaker LCD Resistors #.35 5 Misc # # 25 Total 365 Table 1 From our initial design, it appears to be that the largest cost will be in the large number of sensors and LEDs needed to complete the design. However, we believe we can create this design for around three hundred and fifty dollars. Division of Labor Karine Hopscotch/Atmel/LCD Research Order Components Preliminary Circuit Testing Gameplay design and coding PCB design Game Mat material/design Documentation and Presentation Table 2 Joe Force Sensor/ LED Research Preliminary Circuit Design Test/Debug coding Order PCB design Test/Validation Game Board Assembly Documentation and Presentation Gantt Chart Figure 9