Capacitive Sensing And Old IBM Keyboards

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The pen is mightier than the sword, but the IBM Model M keyboard, properly applied, can knock teeth in. There are a few more IBM keyboards even better suited to blunt force trauma – the extremely vintage beam spring keyboards made for terminals and desktop publishers. Being so very old, there’s no easy way to connect these keyboards to a modern system, so when [xwhatsit] wanted to make his work, he needed to build his own controller.

The beam spring keyboards use capacitive switches, and with 122 keys, the usual method of reading capacitance – putting a capacitor in an oscillator – would be far too slow to be of any use in a keyboard. There is another method of reading capacitance: measuring the current going through the capacitive switch. This can easily be accomplished with an LM339 comparator.

[xwhatsit]‘s keyboard controller uses this capacitive sensing circuit to read the four rows of keys, with a few shift registers taking care of the columns. An ATMega32u2 is the brains of the outfit, running LUFA to translate the key presses to USB.

If you’re lucky enough to have one of these ancient keyboards, [xwhatsit] is selling a few over on the usual mechanical keyboard forums. There’s also a controller for the Model F keyboard using the same basic circuit. If you need one just drop him a line or grab the gerbers and roll your own.

 

 

Laser Etching Brings New Life To An IBM Keyboard

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[Evan] was perusing his local thrift store when he found a beautiful IBM Model M 122-key keyboard made in 1987.

“This is my keyboard, there are many like it, but this one is mine.”

~The Typist’s Creed

In [Evan's] case, this might actually be the only one like it still in use today. An idea formed in his head. What if he took this ancient keyboard, gave it a USB driver, and customized the keys on a hardware level to do exactly what he wanted.

The first step was converting it to USB. He’s using a Teensy 2.0 mostly because it is super inexpensive, and its able to act as a USB HID device. In addition to wiring up the keyboard to the Teensy he’s also added foot pedals that connect via 1/8″ stereo plugs — these kind of act like extra mouse buttons, allowing him to scroll through galleries left to right, add page breaks, and other macros to increase efficiency.

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Using A ThinkPad Keyboard Over USB

kbIt doesn’t have buckling springs, Cherry blues, or even the wonderful if forgotten Alps switches, but the keyboard found in ThinkPads has the best keyboard action of any laptop around. They would make a great USB conversion keyboard, but the board to board connector is very hard to find, and no one has yet managed to get the keyboard and track point working as a USB HID device. Until [rampadc] came along, that is.

[Rampadc]‘s keyboard adapter is built for the ThinkPad T60 keyboard, which is shared between the Lenovo T60, T61, Z60, Z61, R400, R500, T400, T500, and X41 laptops, among many others. The connector is an extremely odd proprietary deal, that can be found through the usual channels for about $5 in quantity 100. On top of this, the keyboard doesn’t have a controller – that’s offloaded to the laptop’s main board. The only electronics in this keyboard is just a matrix. Despite all this, [rampadc] managed to create a breakout board with a decade counter and an SPI GPIO expander.

The board [rampadc] made features one of the proprietary connectors, a few chips, and a receptacle for an Arduino Micro. With just a little bit of code, the old keyboard becomes one of the best portable keyboards in existence, and probably a bit cheaper than the official Lenovo USB-bound ThinkPad keyboard.

[rampadc] has a few of the expansion boards available over on Tindie should you want to build your own. It’s only cost-effective if you have one of these T60 keyboards sitting around in a junk pile; not a likely situation because these machines just don’t die.

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Custom Mechanical Keyboards

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[Wyager] was shopping around for a mechanical keyboard, and after noticing custom PCB manufacturing had come down in price so much, he decided to build his own. The end result is a keyboard that’s so elegant in its design, that it could, with a little work, become a very interesting Kickstarter project.

The design had three requirements: cheap, mechanical switches, and extremely customizable. The cheap requirement was solved by splitting the keyboard into two parts with a master/slave arrangement. The boards are connected by a 1/8″ TRRS jack conveying an I2C bus. Since both boards are identical except for the code running on the Teensy dev boards, [Wyager] saved a bit of cash by using two of the three PCBs that came with his OSHPark order.

The mechanical switches – Cherry MX Blues – are rather expensive parts for a failed project. For fear of failure, [Wyager] first ordered a PCB containing the footprint of only one key. With the footprint correct, he graduated to a 2×2 matrix. Once that was verified, the 6×5 matrix was ordered. Everything worked perfectly the first time, something we can’t say about many of our projects.

The code, board files, and schematics are available over on the github

Hackaday Links: March 9, 2014

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Thinking about starting a CNC machine, 3D printer, or laser cutter project? Misumi has you covered. They’re offering up $150 worth of free stuff with a coupon code. [CharlieX] is putting together a BuildLog laser cutter, a whole bunch of people on reddit are building 3D printers, and I have most of the rods for an i3 build. Just use the promotion code First150 on your order. Actually, read the terms and conditions, but rest assured – this is legit.

A few months ago, we saw this Enigma cypher machine that combines the classic late-30s aesthetic of the original with modern hardware – including a few 16-segment displays. Now there’s a Kickstarter for the Open Source Enigma replica, and it looks like it’s going to end up being pretty popular. Here’s the site with all the deets. Check out that QWERTZ keyboard.

[Jason] has a love of LEGO and a terrible keyboard. Combine the two and he came up with a functional LEGO keyboard. The electronics are, sadly, an old PS/2 membrane keyboard, but the mechanicals are a work of art – all the keys are mounted on a grid of Technic parts that can be positioned over each of the membrane buttons.

Want a really cool look for your next enclosure? How about LED pipes? They’re those clear plastic bits that direct the light from LEDs around corners and can make any enclosure looks like a Star Trek set piece. You can cut these things with a laser cutter like the Alima team did with their indoor air quality meter. Looks pretty cool.

Satisfying way to ‘Build’ Projects

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When you’re writing code for your next big creation, chances are that you build/debug the project 100’s of times a day. Sure, the keyboard hotkey gets the job done, but is it really that satisfying? [Victor] sends in this quick project on turning an Emergency Stop Push button into a ‘Build’ button.

From the looks of it, this project uses a Teensy 2.0, which sports an ATMEGA32U4. Since this part features a USB controller, it is a piece of cake to get it to mimic a keyboard. The circuit is also very simple; the pushbutton contacts are wired from ground to a digital input. On detection of a ‘press’, the Teensy will send out the keyboard combination to build your project: Ctrl-B, F7, etc… If you prefer working within the Arduino IDE, this could upload sketches as well (Ctrl-U).

Adding a little fun to ‘building’ your projects does come at a cost though. Besides forfeiting a Teensy, you also have to give up a precious USB port. [Victor] does mention Bluetooth, but that could break your budget for this sort of project. A possible alternative to the Teensy could be to implement Virtual USB on a low-cost standalone Arduino.

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Keyboard Spoofs 4 NES Controllers for Chiptune Goodness

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This toy keyboard is being used to play music on an NES. As you probably already know, the hardware inside those original controllers was dead simple. They’re just a parallel to serial shift register that reads from all of the keys. To get this keyboard up and running [heavyw8bit] simply mounted eight chips inside the gutted toy, connecting two of them to the keyboard keys, and the rest to the array of push buttons he added to the right.

So what’s the point of using this as a quadruple game controller? Are you expecting to see what a full speed-run of Contra looks like using this as the controls? That’s not the point at all. This becomes a musician-friendly frontend for the NES synthesizer ROM called NESK-1. [heavyw8bit] wrote the game/program in order to allow you to use the original console hardware to play all of the sounds you know and love. Our favorite is the arpeggio example heard at about 2:35 into the clip after the break.

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