Studying typewriter key presses with an Arduino

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 have been hitting costs that middle-class households may justify and even essentially the most primary fashions have been way more sensible than the perfect typewriters in the marketplace. Throughout this era, a variety of electrical typewriters hit the market. As a substitute 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 attention-grabbing a part of the venture 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 akin to a selected key. Artillect related an Arduino Uno board to all of these row/column pins by way of two multiplexer boards. That permit him set any pin to HIGH or LOW. With that skill, he may 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 pace it may well 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.