Physical Computing Used To Be A Thing

In the early 2000s, the idea that you could write programs on microcontrollers that did things in the physical world, like run motors or light up LEDs, was kind of new. At the time, most people thought of coding as stuff that stayed on the screen, or in cyberspace. This idea of writing code for physical gadgets was uncommon enough that it had a buzzword of its own: “physical computing”.

You never hear much about “physical computing” these days, but that’s not because the concept went away. Rather, it’s probably because it’s almost become the norm. I realized this as Tom Nardi and I were talking on the podcast about a number of apparently different trends that all point in the same direction.

We started off talking about the early days of the Arduino revolution. Sure, folks have been building hobby projects with microcontrollers built in before Arduino, but the combination of a standardized board, a wide-ranging software library, and abundant examples to learn from brought embedded programming to a much wider audience. And particularly, it brought this to an audience of beginners who were not only blinking an LED for the first time, but maybe even taking their first steps into coding. For many, the Arduino hello world was their coding hello world as well. These folks are “physical computing” natives.

Now, it’s to the point that when Arya goes to visit FOSDEM, an open-source software convention, there is hardware everywhere. Why? Because many successful software projects support open hardware, and many others run on it. People port their favorite programming languages to microcontroller platforms, and as they become more powerful, the lines between the “big” computers and the “micro” ones starts to blur.

And I think this is awesome. For one, it’s somehow more rewarding, when you’re just starting to learn to code, to see the letters you type cause something in the physical world to happen, even if it’s just blinking an LED. At the same time, everything has a microcontroller in it these days, and hacking on these devices is also another flavor of physical computing – there’s code in everything that you might think of as hardware. And with open licenses, everything being under version control, and more openness in open hardware than we’ve ever seen before, the open-source hardware world reflects the open-source software ethos.

Are we getting past the point where the hardware / software distinction is even worth making? And was “physical computing” just the buzzword for the final stages of blurring out those lines?

Hackaday Europe 2025 Welcomes David Cuartielles, Announces Friday Night Bring-a-Hack

If you’re coming to Hackaday Europe 2025, you’ve got just over a week to get your bags packed and head on out to Berlin. Of course you have tickets already, right? And if you were still on the fence, let us tempt you with our keynote talk and some news about the Friday night meetup, sponsored by Crowd Supply.

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Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The DIY Homing Keys

r/keebgirlies Is Totally a Thing Now

When [coral-bells] posted her first build to r/mechanicalkeyboards, she likely felt some trepidation. After all this is reddit we’re talking about, so right away you’ve got two layers of male-domination hobby.

Most of a lovely plant-themed keyboard.
Image by [coral-bells] via reddit
What she likely didn’t expect was to be upvoted into the tens of thousands, or to receive such a response from other girlies who came out of the woodwork to share their builds.

And so r/keebgirlies was born, and already has a few thousand members. This is a brand-new subreddit for women and non-binary folks who are into mechanical keyboards. As it says in the sidebar, men are welcome but limited to the comments for now, so don’t go trying to post your builds. The girlies are currently seeking moderators, so give that some thought.

As for [coral-bells]’ lovely build, this is an Epomaker MS68 with MMD Vivian V2 switches, and those flowery keycaps are from Etsy. She is currently waiting for supplies to mod a Yunzii AL66, but wants to build a kit at some point.

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Trinteract, a small space mouse, operating in Blender.

Trinteract Mini Space Mouse Does It In 3D

We’re not sure how we managed to miss this one, but better late than never, right? This is Trinteract, a 3-DOF input device that’s both open-source and Arduino compatible. There’s even a neat 3D-printed clip to add it to the side of your laptop.

Imagine navigating 2D and 3D environments, or flying around in Minecraft with ease. [Görkem]’s custom PCB features a Hall effect sensor which picks up readings from the magnet embedded in the bottom of the joystick. You can use any magnetic object as input. In the video below the break, [Görkem] shows a 3D-printed sphere with a disc magnet trapped inside as an alternative. The super-neat part is that the thing moves around entirely on flexures. You know how much we love flexures around here.

[Görkem] has written up a fantastic guide for those who must have one of their own. As a bonus, the guide details the background and thought process behind the design, which we love to see.

Don’t like magnets? This space mouse uses an accelerometer and a spring.

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Puzzle Bobble on a screen with a physical gadget in front

Crafting A Cardboard Tribute To Puzzle Bobble

What do you get when you cross cardboard, deodorant rollers, and a love for retro gaming? A marvel of DIY engineering that brings the arcade classic Puzzle Bobble to life—once again! Do you remember the original Puzzle Bobble aiming mechanism we featured 12 years ago? Now, creator [TomTilly] has returned with a revamped version, blending ingenuity with a touch of nostalgia. [Tom] truly is a Puzzle Bobble enthusiast. And who could argue that? The game’s simplicty makes for innocent yet addictive gameplay.

[Tom]’s new setup recreates Puzzle Bobble’s signature aiming mechanic using surprising materials: deodorant roller balls filled with hot glue (to diffuse LED colours), bamboo skewers, and rubber bands. At its heart is an Arduino UNO, which syncs the RGB LED ‘bubbles’ and a servo-driven aiming arm to the game’s real-time data. A Lua script monitors MAME’s memory locations to match the bubble colours and aimer position.

But this isn’t just a static display. [Tom] hints at a version 2.0: a fully functional controller complete with a handle. Imagine steering this tactile masterpiece through Puzzle Bobble’s frantic levels!

Need more inspiration? Check out other quirky hacks like [Tom]’s deodorant roller controller we featured in 2023. Whether you’re into cardboard mechanics or retro gaming, there’s no end to what clever hands can create.

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Using A Smartphone As A Touchscreen For Arduino

If you want a good display and interface device for an embedded project, it’s hard to look past an old smartphone. After all, you’ve got an excellent quality screen and capacitive touch interface all in the same package! [Doctor Volt] explains how to easily set up your old smartphone to work as a touchscreen for your Arduino.

[Doctor Volt] demonstrates the idea with a 2018 Samsung Galaxy A8, though a wide variety of Android phones can be put to use in this way. The phone is connected to the Arduino via a USB-to-serial converter and an OTG cable. Using a USB-C phone with Power Delivery is ideal here, as it allows the phone to be powered while also communicating with the Arduino over USB.

The RemoteXY app is built specifically for this purpose. It can be installed on an Android phone to allow it to communicate effectively with Arduino devices, which run the RemoteXY library in turn. Configuring the app is relatively straightforward, with a point-and-click wizard helping you designate what hardware you’re using and how you’ve got it hooked up. [Doctor Volt] does a great job of explaining how to hook everything up, and how to build some simple graphical interfaces.

There are a ton of display and interface options in the embedded space these days, many of which can be had cheaply off the shelf. Still, few compete with the resolution and quality of even older smartphones. It’s a neat project that could come in very handy for your next embedded build! Video after the break.

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An homemade automated air freshener dispenser

GPS Enabled Pumpkin Spice Sprayer Knows When It’s PSL Season

Pumpkin spice, also known as allspice with better marketing, has found its way into a seemingly endless amount of products over the years. It goes beyond the obvious foodstuffs of pies and cakes; because there are plenty of candles, deodorants, and air fresheners ready to add a little more spice to your world. One such autumnal smell enthusiast, YouTube user [J-Knows], sought to automate the delivery mechanism with his 3D printed pumpkin spice aerosol sprayer.

The sprayer device uses an Arduino to rotate a small 3D printed arm that depresses the button on an air freshener cap. This design came as a result of multiple attempts to create a clip that would securely attach to a standard canister. When problems arose with the clip slipping out of place after the motor rotated, a pinch of sticky tack ended up being just the solution. With the proper amount of adhesion, the automated sprayer could now “pollute” any space it is in, as [J-Knows] described.

What took this project to another level is the addition of an Adafruit GPS module. It was coded to respond when it was within one mile of a Starbucks — arguably the organization responsible for the pumpkin spice craze. For some the company’s pumpkin spice latte (PSL) is synonymous with all things fall, and marks the beginning of the season when it is brought back to the coffee menu. Though not being a regular coffee drinker himself, [J-Knows] fully committed to the bit by taking his creation on a test trip to his local Starbucks for a PSL. Judging by the amount of pumpkin spice aerosol solution that ended up on his car dash, he is going to be smelling it into the next year.

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