Designers: Frabk Fernandez, Varish Goyal
Client Coordinators: Jean Hartford, Child and Adolescent Life Program, Duke University Medical Center
Supervising Professor: Dr. Larry N. Bohs
A spelling and tactile identification game has been designed as an enjoyable learning tool for visually impaired children. The device operates in one of two modes: spelling or tactile. In spelling mode, the device asks the child to spell a word and the child is given the opportunity to spell it by selecting the appropriate buttons on a custom keyboard. The parent or therapist may choose from six different Braille keyboard overlays so that the child cannot memorize the positions of the objects and letters. In tactile mode, a grid is placed over the keyboard, which allows the placement of 21 objects. The device asks the child to find a specific object and to push the button corresponding to it. In both modes, the child is told whether they are correct or if they should try again. A microprocessor controls digitally sampled voice chips, which talk to the child, asking them to spell words or find objects, and telling them whether or not the correct answer is given.
How this project helped
The spelling and tactile identification game is designed to be both educational and entertaining. It is intended for use by visually impaired children in the playroom at Duke University Hospital. The design is versatile, operating in either spelling mode or tactile mode using six different overlays. Unfortunately, the device must currently be connected to a PC computer, which is unavailable in the playroom. We are developing a standalone version of the project, which will not require connection to the PC.
The spelling and tactile identification game comprises four major components: the input section, the processing unit, the voice chips, and a speaker. The input section consists of two switches and a custom keyboard. A three-position switch determines whether the machine is in spelling mode, in tactile mode, or off. A six-position rotary dial switch selects which overlay is being used. The keyboard consists of 28 push buttons arranged in four rows of seven buttons. In spelling mode the keys correspond to the 26 letters of the alphabet, an enter key, and a next word key. One of six different overlays may be chosen, each containing a Braille letter label for each switch; the labels are in a different order for each overlay. In tactile mode, each button of the top three rows corresponds to one of 21 shapes. The rows of the keyboard are connected to the outputs of a latch, which is driven by four data bits of the microprocessor. The columns of the keyboard are connected to seven of the inputs of a latch, which is read by the microprocessor.
The processing unit consists of a Z180 microprocessor on the Smartcore Z1 Board (Zworld Engineering, Davis, CA). The switch values are latched and read by the microprocessor to determine the mode and the overlay. After determining the mode, the microprocessor commands the voice chips to speak a message such as ‘Can you find the fuzzy ball?’ (in tactile mode) or ‘Can you spell the word dog?’ (in spelling mode). It then scans the keyboard and decides whether or not the correct button(s) is pushed. This is accomplished by latching one of the rows of the keyboard high while holding the others low. The processor then scans the columns to see if any of the buttons are pushed. If no button is pushed, the processor latches the next row high and scans the columns again. This process continues until a pushed button is located, and then a buzzer is sounded to indicate to the child that their push has been registered. Once the key location has been determined, the processor ensures that the key has been released before reading in another key value. In addition, the processor checks to make sure two buttons are not pushed at once. If more than one button is being pushed, it waits until only one button is actuated.
Four ISD90 (Information Storage Devices, San Jose, CA) 90-second voice chips store messages including 200 spelling words, 21 object names, and a few phrases. The microprocessor accesses the recordings using the address lines of the voice chips. When the processor wants to send a specific message, it gives the voice chip the address of the message using its data lines. Because the voice chip has ten address lines while the microprocessor has only eight data lines, two of the address lines on the processor are used along with the data lines to address the voice chips. Two other address lines are used to select which voice chip will be turned on. This minimizes power consumption since three of the four voice chips are in standby mode at all times. When a voice chip is selected, its output is enabled to the speaker using a relay.
The final cost of the spelling and tactile identification game was approximately $541.00.