Studying typewriter key presses with an Arduino

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Studying typewriter key presses with an Arduino

Arduino GroupAugust third, 2022

There was a interval within the late ‘70s and into the ‘80s when typewriter producers tried to maintain up with the tide of the digital age. Private computer systems had been hitting costs that middle-class households might justify and even probably the most primary fashions had been much more sensible than one of the best typewriters in the marketplace. Throughout this era, loads of electrical typewriters hit the market. As an alternative of heavy mechanical linkages, these used daisy wheel mechanisms pushed by computer-style digital keyboards. Artillect transformed one such typewriter, the Brother AX-25, into a pc and used an Arduino to learn key presses.

The pc here’s a Raspberry Pi booting in headless mode to the Debian Linux terminal. However the fascinating a part of the challenge is how Artillect interfaced the Raspberry Pi with the Brother AX-25 typewriter. That typewriter makes use of a keyboard matrix to learn key presses, with every column/row connection equivalent to a particular key. Artillect related an Arduino Uno board to all of these row/column pins by means of two multiplexer boards. That allow him set any pin to HIGH or LOW. With that capacity, he might set off a press of any key and the typewriter would print that character.

As a result of the Arduino was controlling the typewriter output, Artillect simply needed to feed it textual content from the Linux terminal. The Raspberry Pi has a built-in UART for serial communication and the Arduino can learn that output. In headless mode, the Raspberry Pi outputs every part within the terminal to that serial port. The Arduino receives that, buffers the textual content, after which sends the important thing presses to the typewriter at a velocity it could deal with. As a result of the Arduino solely outputs to the typewriter keyboard and doesn’t learn its key presses, Artillect needed to remotely hook up with the Raspberry Pi’s terminal with a laptop computer to enter instructions. Even so, it’s neat to see the typewriter clacking away by itself because it prints the terminal output. 

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