The Challenge: The assignment was to create a telegraph key to be used to communicate with a partner across the room. I took this several steps further, and challenged myself to create a machine that would interpret my partner’s Morse Code message and display it on a screen.
Technical Approach: The heart of my device was a small computer-on-a-chip produced by a company called Parallax. I taught myself how to program this computer to listen for the telegraph key to be pressed, and then to interpret the signal as a dot or a dash depending on how long the key was held down. The chip then converted the series of dots and dashes into characters by looking up the Morse Code letters in a table. The computer then displayed this information on a screen.
Selected Design Features: To maximize usability, I included a switch which allows the user to plug the unit into a wall outlet through a power adapter, or to get power from internal batteries. I also mounted red and yellow LEDs on the front panel, allowing the user to visually identify dots and dashes as they are interpreted by the onboard computer. To improve visibility, I decided to use an inverse yellow and black display, allowing the yellow letters to shine through the black background.
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| The startup splash screen. | With the rear panel removed. |
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| An internal view of the front panel. | The circuit board mounted to the rear panel. |
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| The heart of the machine... powered by a Parallax BS2SX. | Dry-transfer decals and an acrylic stand. |