Translating An Old Display To A New One

November 5, 2026 by Jenny List 26 Comments

A quick search through AliExpress will find PCBs that take HDMI or VGA and translate them to DSI lanes for TFT panels, and even boards that translate DSI to HDMI in the other direction. Usually they need dedicated silicon or if you’re doing it yourself, an FPGA, but depending on the display that need not be the case. As an example, [Voltage Ventures] has replaced a defective STN display with a more modern one using nothing more complex than a Raspberry Pi Pico.

The display comes as part of a Samsung cash register that looks as though it comes from the 1990s, which is in keeping with it having a monochrome STN display. A replacement was going to cost a fortune, so some way of translating between the two was in order. It has a 4-bit data bus, so there’s a description of how they sampled the bus and identified the timing used. It’s hardly the highest resolution display by today’s standards, being a meager 320 by 240 pixels. Once the format is known it’s a case of transposing it to monochrome VGA in the microcontroller. Initial work was done with an STM series chip, later this was moved to the RP2040.

We like this project, and it’s a reminder that even something broken and old can still be rescued.

Clotty The Custom Period Tracker Can, Of Course, Run DOOM

October 21, 2026 by Donald Papp 27 Comments

[kati]’s Clotty might run DOOM and game-ify the menstrual tracking process with a playful Tamagotchi-like aspect, but don’t let that distract you. It is, at its heart, a personal menstrual cycle tracking device that is defined as much by what it does do as what it doesn’t.

What doesn’t it do? Well, it will never quietly upload one’s menstrual tracking data to a remote server. Nor will it harvest, mishandle, disclose, or sell that same data. Shamefully, that alone sets it far apart from the wide range of period tracking services and apps out there. Also setting it apart is its cheerful lack of discretion. As [kati] puts it, she wanted Clotty’s design to scream “HELLO I AM A PERIOD TRACKING DEVICE” and at this she absolutely succeeded.

Clotty uses an RP2040, color LCD display, and a small variety of sensors built into a palm-sized, uterus-shaped PCB complete with touchpad ovaries. Right now it’s still in its early stages, and basically at the point that everything works hardware-wise and the essentials are there for software, but it’s still in active development. Keep an eye on Clotty’s GitHub repository for updates as features get fleshed out.

Of course, as [kati] observes, the core validity of a device can be defined by whether it can run DOOM, which of course Clotty can. You can find [kati]’s fork of RP2040-DOOM here.

[kati] has a knack for designing effective hardware that gamifies functions and incorporates a playfulness to the design that’s a delight to see. Take a moment to check out her Slightly Sentient D20 which is another excellent example of the kind of work she does.

The 10€ Gamepad

October 16, 2026 by Al Williams 10 Comments

We aren’t sure what [Lazy_Duck] is doing with video games, but it must require a lot of controllers. Dismayed at the cost and complexity of commercial gamepads, they started soldering and 3D printing to get a cheaper basic controller.

The emphasis is on throwing things together, so there’s no dedicated PCB. Just a protoboard with an RP2040-Zero, a joystick, a few buttons, and a microswitch. A 3D-printed case rounds out the project.

Continue reading “The 10€ Gamepad” →

2026 Retrocomputing Challenge: USBSID-Pico Has Two SIDs, Many Inputs

October 13, 2026 by Tyler August 14 Comments

We’ll give you three guesses what the most important bits of silicon in [LouD]’s USBSID-Pico are, and two don’t count. Yes, there’s a Raspberry Pi Pico, and a pair of the unforgettable SID chips from MOS– the sound chip of the C64, the die that launched a thousand chiptunes. Well, unless you build it with a hardware SID replacement, but the goal of this device is to get SIDs hooked up to modern hardware.

To that end, USBSID-Pico can be controlled via USB– obviously– in the form of CDC/WebUSB/WebSerial but also MIDI, and even ASID, which is a specific protocol for streaming SID register data over MIDI. You might be wondering the point, since surely you can get cycle-accurate SID emulation on an RP2040, right? Well, not everyone agrees that cycle-accurate emulation is accurate enough; like the people who swear by the subtle distortions tube amplifiers introduce into the sound, some say the chip’s own inaccuracies give the sound out of the physical device a unique vibe emulators don’t match. That’s a fight for others to litigate; we just appreciate the work that went into getting these old sound chips talking to modern hardware, and getting the project certified as Open Source Hardware.

This combination of old sound and new microcontroller makes the USBSID-Pico a good entry for our ongoing retrocomputing contest, particularly the retro-modern category. Just be aware of PAL and NTSC differences with these old chips, or your beeps and boops might be out of tune. They haven’t made them in decades, but there are more than a few modern replacements for the MOS 6581.

A Modular Macro Keypad

September 26, 2026 by Bryan Cockfield 9 Comments

The introduction of the ATmega32U4 microcontroller, with its integrated USB controller, made a lot of hardware tasks much simpler than they were before. One of the arenas it revolutionized was custom keyboards, making it much easier to build not only standard mechanical keyboards, but keyboards of all kinds of shapes and layouts and custom macro keyboards as well. This trend has continued on for the better part of the past decade with other microcontrollers beyond the 32U4 now available as well, but this modular macro keypad takes it to a new level by keeping that simplicity but also keeping costs down.

The suutari20, as it is called by its creator [Squalius] is able to achieve these aims by using 3.5 mm jacks commonly found in audio equipment. Each jack can support up to three keys, with the hub ultimately able to support 18 different keys. Those can include analog devices as well, such as volume knobs or jog controllers. The macro pad is powered by an RP2040 microcontroller from a Raspberry Pi Pico and uses QMK firmware, so those already familiar with custom keyboard programming will have no problem getting started.

From there, all that’s needed is a case, in this example a 3D printed one, and the commodity audio hardware to plug everything in to. It enables whatever functions can be thought of in a macro pad, and although the design focuses on simplicity and cost, this macro pad takes the concept to the extreme with modular keys that each have their own microcontroller built-in.

Continue reading “A Modular Macro Keypad” →

A Thoroughly Modern Minimalist Transceiver

September 3, 2026 by Jenny List 9 Comments

Making a radio is so often a case of taking tried and tested designs and working with them to create something new. It’s a safe way to make something that works. [Riyas] however has gone for an entirely different tack, creating an entirely modern transceiver with as much as possible going on in the silicon.

At its heart are three integrated circuits, the familiar Si5351 as a transmit VFO, an Si4372 receiver, and an RP2040 tying it all together. This microcontroller functions both as controller, and as an ADC to provide a software defined radio via its USB port. The Si4372 having an internal SDR architecture and its output being digitized again is not lost on us.

It’s for digital modes and CW only, but we’d venture the opinion that those are where the interesting stuff is anyway. We certainly like it for its simplicity, and also for the one-cable solution it offers. So many other designs need a sound card and extra cables, this one makes for a lot less clutter. We hope we’ll see more development on this design over time, it could become a favorite in the homebrew rig stakes.

Meanwhile the Si5351 is notoriously annoying to program. A while back we covered a library that might help, if you get stuck.

Your Laptop Keyboard, On Another Device

August 12, 2026 by Jenny List 28 Comments

It’s likely many of us have been in the position of first set-up on a machine such as a Raspberry Pi, and had keyboard problems. Either no spare keyboard is to be found, or a cluttered desk has to find extra space for a full-size keyboard. [Þórarinn] and [Arni] have a handy solution: use the existing keyboard on your laptop.

His approach is both ingenious and simple, as it’s only the K part of a KVM. On the laptop end, it’s a serial terminal, without the receiving side. The serial port in question is an RP2040 board which implements a USB-to-serial port. This serial connection goes to another RP2040, which does the ingenious bit. It’s a serial-to-USB HID keyboard. All of this means that keystrokes on the laptop are sent down the serial connection, and appear on the Pi or whatever computer as a USB keyboard as though typed locally. The mildly annoying first set-up can be done, and then it can be run via SSH or whatever other remote access protocol as normal. The code is provided, so anyone with a couple of RP2040 boards can do it.

We like this hack, because we’ve had the annoyance of needing a keyboard to set up what would otherwise be a completely headless machine too many times. It’s one to store away at the back of your mind, for those rare improvisational need-an-extra-keyboard moments.

Thanks [Henk] for the tip.