A black OLED screen with a happy face displayed upon it is situated at the top of a squarish calculator with a 5x6 grid of white calculator keys. It floats above a graphing calculator, Nintendo Switch, aigo numpad, and an Arduino Mega on a white table. A handful of differently-colored kalih choc switches are in various places around the table.

Mechanical Switch Sci-Calc Is Also A Macropad

October 4, 2024 by Navarre Bartz 6 Comments

Smartphones have replaced a desktop calculator for most folks these days, but sometimes that tactility is just what you need to get the mathematical juices flowing. Why not spruce up the scientific calculator of yore with the wonders of modern microcontrollers?

While you won’t be able to use Sci-Calc on a standardized test, this classy calculator will let you do some pretty cool things while clacking on its mechanical choc switches. Is it a calculator? Obviously. Is it an Arduboy-compatible device that can play simple games like your TI-84? Yes. Is it also a macropad and ESP32 dev board? Why not? If that isn’t enough, it’s also takes both standard and RPN inputs.

[Shao Duan] has really made this device clean and the menu system that rewrites main.bin based on the program selection is very clever. Escape writes main.bin back into the ROM from the SD card so you can select another application. A few classic games have already been ported, and the process looks fairly straightforward for any of your own favorites.

If you’re hankering for more mathy inputs, checkout the Mathboard or the MCM/70 from 1974.

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Reverse Time Back To The Days Of RPN

September 26, 2024 by Bryan Cockfield 68 Comments

While Texas Instruments maintains dominance in the calculator market (especially graphing calculators), there was a time when this wasn’t the case. HP famously built the first portable scientific calculator, the HP-35, although its reverse-Polish notation (RPN) might be a bit of a head-scratcher to those of us who came up in the TI world of the last three or four decades. Part of the reason TI is so dominant now is because they were the first to popularize infix notation, making the math on the calculator look much more like the math written on the page, especially when compared to the RPN used by HP calculators. But if you want to step into a time machine and see what that world was like without having to find a working HP-35, take a look at [Jeroen]’s DIY RPN calculator.

Since the calculator is going to be RPN-based, it needs to have a classic feel. For that, mechanical keyboard keys are used for the calculator buttons with a custom case to hold it all together. It uses two rows of seven-segment displays to show the current operation and the results. Programming the Arduino Nano to work as an RPN calculator involved a few tricks, though. [Jeroen] wanted a backspace button, but this disrupts the way that the Arduino handles the input and shows it on the display but it turns out there’s an Arudino library which solves some of these common problems with RPN builds like this.

One of the main reasons that RPN exists at all is that it is much easier for the processor in the calculator to understand the operations, even if it makes it a little bit harder for the human. This is because early calculators made much more overt use of a stack for performing operations in a similar way to Assembly language. Rather than learning Assembly, an RPN build like this can be a great introduction to this concept. If you want to get into the weeds of Assembly programming this is a great place to go to get started.

A Lenovo Yoga with a mechanical keyboard, held up by its creator.

Mechanical Keyboard + Laptop = Clacktop

July 18, 2024 by Kristina Panos 20 Comments

What do you do when your laptop keyboard breaks for the second time? Well, most people might use an external keyboard until they couldn’t take it anymore and bought a new machine. But [Marcin Plaza] isn’t most people.

It took more than twelve hours of CAD, but [Marcin] redesigned the case to be at least twice as thick as the Lenovo Yoga that inspired this project in order to accommodate a slimmed-down mechanical keyboard. Further weight-loss surgery was required in order to make the keyboard fit, but the end result is kind of a marvel of engineering. It’s marriage of sleek modernity and early laptop chonky-ness, and we love it.

Lacking a complete metal fab shop of one’s own, [Marcin] elected to have a board house fab it out of titanium and was quite surprised by the result. We really like the clear acrylic bottom, into which [Marcin] drilled many holes for airflow. Be sure to check out the build and demo video after the break.

Did you initially wonder whether the new case was printed? That’s totally a thing, too.

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Building A Mechanical Keyboard As A Learning Project

May 2, 2024 by Lewin Day 2 Comments

[Thomas Rinsma] wanted to learn about designing PCBs. Thus, he set about a nifty project that would both teach him those lessons and net him something useful in the process. The result was kb1, a mechanical keyboard of his own design!

You might think [Thomas] would have started with a basic, barebones design, but he didn’t shy away from including some neat features. His keyboard has a “tenkeyless” layout, and uses Cherry MX-style switches, as has become the norm in the mechanical keyboard world. It has a 16×2 LCD display for user feedback, a rotary encoder, and it even has an RGB backlight for every key thanks to SK6812 addressable LEDs. Running the show is a Raspberry Pi Pico, equipped with the KMK firmware. The board actually uses twin PCBs as the enclosure, which is a nifty trick.

It’s remarkably fully featured for a first time build.

Nyan Keys: Because Your Keyboard Is Painfully Slow

December 10, 2023 by Kristina Panos 32 Comments

You probably don’t notice keyboard latency when typing or doing mundane tasks, but if you start gaming, that’s also when you might start complaining. Every millisecond counts in that arena. Think your keyboard is fast? Think again. Because unfortunately, no matter what you’ve got in there, that key matrix is slowing you down. What you need is an FPGA-based keyboard with an overkill MCU. You need Nyan Keys.

[Portland.HODL] set out to make the lowest-latency mechanical keyboard possible that would accept any Cherry-compatible switches, and boy howdy, is this thing fast.

Coupled with the STM32F723VET6 MCU is USB 2.0 HS, which has an 8000Hz polling rate. At worst, key latency measures 30μS, which blows the 1mS average out of the water.

Because it uses a Lattice Semi iCE40HX 4k FPGA, each key switch can connect to its own I/O pin, which also eliminates the need for diodes.

It also means that each key switch can have its own “core” — an 8-bit timer that is always counting up to 255. The key can only change its state when the timer reads 255. This acts as a rather clever debounce mechanism.

If all that’s not enough, [Portland.HODL] built an operating system called NyanOS written in C to avoid any performance-reducing overhead. Oh, and it has an opt-in Bitcoin miner.

We’ve seen a lot of keyboards, the fast ones are fast because of the input side — they are chording keyboards that take combinations to type, rather than using one key (or so) per character. The Characorder is so fast that it was banned from competition.

Solenoid Keyboard Sounds Very Much Like A Typewriter

July 19, 2023 by Lewin Day 29 Comments

Mechanical keyboards are muchly adored things. For many of us, they take us back to that loud clickity-clack that was so common before consumer keyboards went to membrane switches. For others, it’s just for the pure joy of the finger-powered symphony. The solenoid edition of the Red Herring keyboard from [Ming-Gih Lam] understands the beauty of this sound intimately. It can be nearly silent if you so desire, or it can clack away with the best of them (via Hackster.io).

It all comes down to the switches used in the design. [Lam] selected the Silent Alpacas from Durock, noted for their quiet operation, particularly when lubricated. You get just a faint slide-and-click noise from the keyboard under regular use.

The joy of the solenoid edition is in, you guessed it, the solenoid. It fires away with every keypress when enabled, creating a sound more akin to a real typewriter than any mechanical keyboard we’ve ever heard. Click-clack fans will love it, while those with sensitive ears will scream at any cube neighbours that dare to buy one and switch it on.

Files are available on Github for the curious. We’ve seen some other great keyboards over the years, like this nifty split-board design. Video after the break.

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Taking Mechanical Keyboard Sounds To The Next Level

July 13, 2023 by Bryan Cockfield 10 Comments

When it comes to mechanical keyboards, there’s no end to the amount of customization that can be done. The size and layout of the keyboard is the first thing to figure out, and then switches, keycaps, and then a bunch of other customizations inside the keyboard like the mounting plate and whether or not to add foam strips and other sound- and vibration-deadening features. Of course some prefer to go the other direction with it as well, omitting the foam and installing keys with a more noticeable click, and still others go even further than that by building a separate machine to make their keyboard activity as disruptive as it could possibly be.

This started as a joke among [ac2ev] and some coworkers, who were already teasing about the distinct sound of the mechanical keyboard. This machine, based on a Teensy microcontroller, sits between any USB keyboard and its host computer, intercepting keystrokes and using a small solenoid to tap on a block of wood every time a keystroke is detected. There’s also a bell inside that rings when the enter key is pressed, similar to the return carriage notification for typewriters, and as an additional touch an audio amplifier with attached speaker plays the Mario power-up sound whenever the caps lock key is pressed.

[ac2ev] notes that this could be pushed to the extreme by running a much larger solenoid powered by mains electricity, but since this was more of a proof-of-concept demonstration for some coworkers the smaller solenoid was used instead. The source code for the build can be found on the project’s GitHub page and there’s also a video of this machine in action here as well. Be careful with noisy mechanical keyboards, though, as the sounds the keys produce can sometimes be decoded to determine what the user is typing.