2018-08-23 (Th) Emergency Rotary Keyboard EmerKeyB

Have you ever seen a gadget online and thought to yourself, “That’s so cool and practical I should get one today in case I need it,” but then it sits on a shelf and you never touch it? That’s probably what I’m building. It will probably go down in my memory as the way I learned to use a Digispark clone as a keyboard and it will probably go down in my toolbox as a fragile bauble. At best, it will become a useful shield for someone else who happens to need a rotary encoder for a Digispark.

The premise of the device is simple, a rotary encoder with pushbutton will be mounted on top of a Digispark, a tiny Arduino-compatible board, and emulate a keyboard. As the encoder is turned, a character is subsequently deleted and replaced with a new character. In this way, a full keyboard’s worth of characters can be typed with a single encoder.

The size of the device is an appealing factor. It would be laborious to type anything longer than a password but in the emergency situation of a broken smartphone touchscreen and the absence of a full-size keyboard, this would be a lifesaver. Unlike projects which can claim things like, “World’s smallest keyboard,” or “Most basic keyboard,” or “simplest keyboard,” this won’t require any training. Anyone familiar with letters, numbers, and symbols who can twist and press a know can figure this out in less than a minute as opposed to memorizing ASCII tables or learning Morse Code. Cost is also an appealing factor. It should be so inexpensive that it makes it cheap as a hobby project since all the parts were at my workshop and in the off-chance that I get to use it in a pinch, I’ll look like a genius-hero.

Enough background

Pseudo-code was written without looking at the example or library for the Digistump keyboard library. The most logical method was to type a letter then wait for another command. If the next command was a new letter, the original was deleted and replaced with the new one. Pressing the integrated button will allow the letter to remain in place. Long-pressing the button will hold the backspace key. When the button is pressed without twisting the encoder, the enter key is pressed.

Without a supplementary display, this will be useless in applications where the typed letters cannot be seen or if typing a particular letter would instantly evoke a change. The primary purpose would be to enter a password or short text command.

Pseudo-code and ASCII table

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The rest of the posts for this project have been arranged by date.

First time here?

Completed projects from year 1
Completed projects from year 2
Completed projects from year 3
Completed projects from year 4
Completed projects from year 5

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