circular display

9 Articles

A render of the moon, on a circular display.

Put The Moon On Your Desk

May 20, 2026 by 8 Comments

Most people take the Moon for granted, not considering its slow cycle where the sun gradually illuminates different parts of it. A recent project from [Karsten Mueller] helps you keep our nearest celestial neighbor in mind by putting a tiny version on your desk. (German)

The device itself is made with a circular display, an ESP32-S3, and a simple 3D printed case. But the interesting part is the software — it’s not just a moon phase display, it actually takes your local time, latitude and longitude into account. The resulting image is an approximation of what the moon looks like if you were to look at it, even if you wouldn’t actually be able to see it, such as when it is obscured by the Earth or barely visible during the daylight sky. Initially the project actually used a photograph of the Moon that [Karsten] personally snapped, but there’s also an option to pull the imagery from NASA.

The original write-up is in German, but there’s also an English page for the project on Hackaday.io, and the source is available on GitHub if you’d like to put one together yourself.

Is That A Large Smartwatch? Or A Tiny Cray?

June 21, 2024 by 7 Comments

While we aren’t typically put off by a large wristwatch, we were taken a bit aback by [Chris Fenton]’s latest timepiece — if you can call it that. It’s actually a 1/25th-scale Cray C90 worn as a wristwatch. The whole thing started with [Chris] trying to build a Cray in Verilog. He started with a Cray-1 but then moved to a Cray X-MP, which is essentially a Cray-1 with two extra address bits. Then he expanded it to 32 bits, which makes it a Cray Y-MP/C90/J90 core. As he puts it, “If you wanted something practical, go read someone else’s blog.”

The watch emulates a Cray C916 and uses a round OLED display on the top. While the move from 22 to 32 address bits sounds outdated, keep in mind the Cray addresses 64-bit words exclusively, so we’re talking access to 32 gigabytes of memory. The hardware consists of an off-the-shelf FPGA board and a Teensy microcontroller to handle mundane tasks like driving the OLED display and booting the main CPU. Interestingly, the actual Cray 1A used Data General computers for a similar task.

Of course, any supercomputer needs a super program, so [Chris] uses the screen to display a full simulation of Jupiter and 63 of its moons. The Cray excels at programs like this because of its vector processing abilities. The whole program is 127 words long and sustains 40 MFLOPs. Of course, that means to read the current time, you need to know where Jupiter’s moons are at all times so you can match it with the display. He did warn us this would not be practical.

While the Cray wouldn’t qualify as a supercomputer today, we love learning about what was state-of-the-art not that long ago. Cray was named, of course, after [Seymour Cray] who had earlier designed the Univac 1103, several iconic CDC computers, and the Cray computers, of course.

ZSWatch: This OSHW Smart Watch Is As DIY As It Gets

January 16, 2023 by 17 Comments

We say it often, but it’s worth repeating: this is the Golden Age of making and hacking. Between powerful free and open source software, low-cost PCB production, and high resolution 3D printers that can fit on your desk, a dedicated individual has everything they need to make their dream gadget a reality. If you ever needed a reminder of this fact, just take a look at the ZSWatch.

When creator [Jakob Krantz] says he built this MIT-licensed smart watch from scratch, he means it. He designed the 4-layer main board, measuring just 36 mm across, entirely in KiCad. He wrote every line of the firmware, and even designed the 3D printable case himself. This isn’t some wearable development kit he got off of AliExpress and modified — it’s all built from the ground up, and all made available to anyone who might want to spin up their own version.

The star of the show is the nRF52833 SoC, which is paired with a circular 1.28″ 240×240 IPS TFT display. The screen doesn’t support touch, so there’s three physical buttons on the watch for navigation. Onboard sensors include a LIS2DS12 MEMS accelerometer and a MAX30101EFD capable of measuring heartrate and blood oxygen levels, and there’s even a tiny vibration motor for haptic feedback. Everything’s powered by a 220 mAh Li-Po battery that [Jakob] says is good for about two days — afterwards you can drop the watch into its matching docking station to get charged back up.

As for the software side of things, the watch tethers to a Android application over Bluetooth for Internet access and provides the expected functions such as displaying the weather, showing notifications, and controlling music playback. Oh, and it can tell the time as well. The firmware was made with extensibility in mind, and [Jakob] has provided both a sample application and some basic documentation for would-be ZSWatch developers.

While an unquestionably impressive accomplishment in its current form, [Jakob] says he’s already started work on a second version of the watch. The new V2 hardware will implement an updated SoC, touch screen, and an improved charging/programming connector. He’s also looking to replace the 3D printed case for something CNC milled for a more professional look.

The ZSWatch actually reminds us quite a bit of the Open-SmartWatch project we covered back in 2021, in that the final result looks so polished that the average person would never even take it for being DIY. We can’t say that about all the smartwatches we’ve seen over the years, but there’s no question that the state-of-the-art is moving forward for this kind of thing in the hobbyist space.

Getting Familiar With Round Displays

December 11, 2021 by 29 Comments

Once upon a time, maker projects were limited to using simple character displays or those salvaged from popular Nokias, largely due to cost. These days, a small OLED or LCD is available for just a few bucks. However, you can go fancier, and [Mr. Volt] does just that with an exploration of nice round displays.

Using round displays doesn’t have to be hard, with plenty of great products on the market. [Mr. Volt] goes through various options, from the cheap bare screens you can hook up to a microcontroller, to larger models designed for direct use with the Raspberry Pi or even straight HDMI inputs. Many are quite high resolution, and look particularly beautiful when driven with appropriate artwork.

However, there are a few tricks that come in handy when you’re going away from traditional rectangular screens. Screen mounts on some models may not be directly aligned with the center of the circular display, which can lead to results that look off if not accounted for.

It’s also important to remember that round displays are still driven like square displays, using Cartesian coordinates. Trying to use software with interface elements around the edges can be trying, as many end up rendered off-screen. Instead, circular displays are best used to display purpose-made content, rather than used with traditional software expecting a rectangular screen.

Fundamentally, round displays are a neat thing to have, as they allow for the construction of elegant projects that don’t have to abstract a circle with cheats like obscuring bezels or housings. Video after the break.

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Tackle The Monkey: Raspberry Pi Gets Round Screen

October 25, 2021 by 18 Comments

You could argue that the project to add a round screen to a Raspberry Pi from [YamS1] isn’t strictly necessary. After all, you could use a square display with a mask around it, giving up some screen real estate for aesthetics. However, you’d still have a square shape around the screen and there’s something eye-catching about a small round screen for a watch, an indicator, or — as in this project — a talking head.

The inspiration for the project was a quote from a Google quote about teaching a monkey to recite Shakespeare. A 3D printed monkey with a video head would be hard to do well with a rectangular screen, you have to admit. Possible with a little artistry, we are sure, but the round head effect is hard to beat. Honestly, it looks more like an ape to us, but we aren’t primate experts and we think most people would get the idea.

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An Open Source Smart Watch You’d Actually Wear

April 8, 2021 by 39 Comments

We’ve seen a number of open source smart watches over the years, and while they’ve certainly been impressive from a technical standpoint, they often leave something to be desired in terms of fit and finish. Exposed PCBs and monochromatic OLED displays might be fine for a trip to the hackerspace, but it wouldn’t be our first choice for date night attire.

Enter the Open-SmartWatch from [pauls_3d_things]. This ESP32 powered watch packs a gorgeous circular 240×240 TFT display, DS323M RTC, BMA400 three-axis accelerometer, and a 450 mAh battery inside of a 3D printed enclosure that can be produced on your average desktop machine. WiFi and Bluetooth connectivity are a given with the ESP32, but there’s also an enhanced edition of the PCB that adds another 4 MB of RAM, a micro SD slot, and a Quectel L96 GPS receiver.

The GPS edition of the PCB

As it’s an open source project you’re free to download the PCB design files and get the board produced on your own, but [pauls_3d_things] has actually partnered with LILYGO to do a run of the Open-SmartWatch electronics which you can pick up on AliExpress right now for just $24 USD. You’ll still need to order the battery separately and 3D print your own case, but it still seems like a pretty sweet deal to us.

On the software front, things are pretty basic right now. The watch can update the time from NTP using a pre-configured WiFi network, and there’s a Bluetooth media controller and stopwatch included. Of course, as more people get the hardware in their hands (or on their wrists, as the case may be), we’ll likely start seeing more capabilities added to the core OS.

While getting our own code running on commercially produced smartwatches holds a lot of promise, the Open-SmartWatch is arguably the best of both worlds. The partnership with LILYGO brings professional fabrication to the open hardware project, and the GPLv3 licensed firmware is ripe for hacking. We’re very excited to see where the community takes this project, and fully expect to start seeing these watches out in the wild once we can have proper cons again.

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