Celebrating Pi Day With A Ghostly Calculator

For the last few years, [Cristiano Monteiro] has marked March 14th by building a device to calculate Pi. This year, he’s combined an RP2040 development board and a beam-splitting prism to create an otherworldly numerical display inspired by the classic Pepper’s Ghost illusion.

The build is straightforward thanks to the Cookie board from Melopero Electronics, which pairs the RP2040 with a 5×5 matrix of addressable RGB LEDs. Since [Cristiano] only needed 4×5 LED “pixels” to display the digits 0 through 9, this left him with an unused vertical column on the right side of the array. Looking to add a visually interesting progress indicator for when the RP2040 is really wracking its silicon brain for the next digit of Pi, he used it to show a red Larson scanner in honor of Battlestar Galactica.

With the MicroPython code written to calculate Pi and display each digit on the array, all it took to complete the illusion was the addition of a glass prism, held directly over the LED array thanks to a 3D-printed mounting plate. When the observer looks through the prism, they’ll see the reflection of the display seemingly floating in mid-air, superimposed over whatever’s behind the glass. It’s a bit like how the Heads Up Display (HUD) works on a fighter jet (or sufficiently fancy car).

Compared to his 2023 entry, which used common seven-segment LED displays to show off its fresh-baked digits of Pi, we think this new build definitely pulls ahead in terms of visual flair. However, if we had to pick just one of [Cristiano]’s devices to grace our desk, it would still have to be his portable GPS time server.

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HUD-Like Clock Is A Transparent Time Display

While we have all types of displays these days, there’s something special about those that appear to float in the air. This HUD clock from [Kiwi Bushwalker] is one such example.

The build relies on four 8×8 LED matrixes to display the four digits that make up the time, run by the MAX7219 driver chip. However, the LEDs aren’t viewed directly — that would be too simple. Instead, the matrixes shoot their light up at an angle towards a tilted piece of clear acrylic. This creates a “heads-up display” look where the numbers appear to float in the air.  The clock gets accurate time from an NTP time server over WiFi, thanks to the ESP32 microcontroller that runs the show.

It’s a straightforward clock build in many ways, but we particularly like the use of the heads-up display technique. It’s almost surprising we don’t see these projects more often, for things like car dashboard displays or targeting womp rats in a T-16 landspeeder. If you’ve been whipping up your own HUD projects, don’t hesitate to notify the tipsline!

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Garmin HUD Got Discontinued, But Not Trashed

The Garmin HUD+ was a small Bluetooth device intended for the dashboard of a car, meant to be used as a GPS heads-up display for data from Garmin smartphone apps. It used a bright VFD (vacuum fluorescent display) which was viewed through a clear reflector, and displayed GPS information and directions. It was discontinued in 2015, but [Doz] was fond of his and used it happily until a phone upgrade meant it no longer worked. Was it destined for a landfill? Not if he had anything to say about it!

The first thing [Doz] tried was using an alternate Android app, but since it also didn’t work, it was time to sit back and reflect on the scope of the issue. In [Doz]’s case, he really only wanted some basic meaningful data displayed, and decided he could do away with the phone altogether if he had the right hardware. Continue reading “Garmin HUD Got Discontinued, But Not Trashed”

Arduino Car HUD Does The Job

Many cars these days come with a basic Heads Up Display, or HUD. Typically, these display speed, though some also throw in a tachometer or navigational graphics too. Of course, if your car doesn’t have one of these stock, hacking in your own is always an option.

[PowerBroker2] developed this HUD in a somewhat circuitous way, but it’s effective nonetheless. An ELM327 Bluetooth OBD-II reader is hooked up to the car, collecting data on speed and RPM. This data is passed to an ESP-32 and Teensy 3.5. From reading the code, it appears the Teensy is responsible for logging data from the CAN bus on an SD card, and running a small OLED display. The ESP32 is then charged with running the LED display that actually forms the HUD. It’s then combined with a 3D-printed housing, some plexiglass, and reflective windshield film to complete the effect.

It’s a build that probably packs in more hardware than is strictly needed to get the job done, but it does indeed get the job done. Other builds we’ve seen use LED strips as a quick and tidy way to get the job done. Video after the break. Continue reading “Arduino Car HUD Does The Job”

Python And Pi Provide Heads Up Display For Your Experimental Airplane

You shouldn’t be looking at screens when you’re driving, but what about a heads-up display? A screen that could put relevant information in your field of vision would be great, even more so if it used a Raspberry Pi. That’s exactly what [John] did, only he did it with an airplane.

First up, the legality of this build. [John]’s plane is registered as experimental, which, provided you know what you’re doing, is pretty close to ‘anything goes’ as you would want in a manned aircraft. [John] has a sufficient number of hours in his log book, and he’s built a Zenith 701.

For hardware, the hard part of this build is constructing a heads-up display. Fortunately, aftermarket HUDs exist, and [John] is using a Kivic projector, a $200 piece of equipment that’s readily available on Amazon. If you need a HUD for your car, there you go. The software is another thing entirely, with the goal of having the software decoupled from the display and data sources. This is somewhat easy to accomplish with a Raspberry Pi; the display is actually just some minimal text-based blocky graphics built in PyGame. This build is also decoupled from the data sources by building this as a user interface for Stratux, an independent Raspberry Pi-based ADS-B receiver for pilots.

There are several views available with this HUD, with the AHRS + ADS-B providing information on the aircraft’s attitude and altitude, along with a few indicators of the nearest planes. The traffic view expands on the ADS-B data, showing the nearest eight or so aircraft in the air, with a range, bearing, and difference in altitude. There’s a diagnostic window, and since [John]’s plane is a backcountry STOL thingamado that can hover in a strong wind, there’s also a digital version of a norden bombsight. It’s for dropping bags of flour onto a grass strip. You can check out [John]’s entire AirVenture presentation of the build below, with all the code available here.

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Hackaday Prize Entry: Pi-Driven Google Glass

[Ricardo Ferro] didn’t want to buy a Google Glass, so he made his own.

The Raspberry Pi Zero Prism consists of a 3D-printed headset the side-pieces of which hold a variety of electronic components, including a Pi Zero running Raspbian Jessie, a Pi Noir IR camera, a WiFi/Bluetooth module and a whole mess of SMD tactile push buttons. Video output is provided by a Kopin 922K display module. This module is usually used in smart goggles and uses a prism to reflect information into the wearer’s field of view.

One application [Ricardo] envisions for this Open Source Google Glass is using it in conjunction with facial recognition software and the YouTube-favorite IR camera trick of seeing through clothing. No, he’s not using it for that idea, and you should get your mind out of the gutter. [Ricardo] wants to identify masked criminals. Setting aside the technological challenges of making that technology work, we think that walking around with x-ray specs is likely to get those specs broken off your face by someone who wears clothes for modesty purposes. Still, it’s a fascinating project and we love the way the prism and video assembly comes together.

Heads-Up Display Turns Car Into Fighter Jet

While most of us will never set foot in a fighter jet, some of us can still try to get as close as possible. One of the most eye-catching features of a fighter jet (at least from the pilot’s point-of-view) is the heads-up display, so that’s exactly what [Frank] decided to build into his car to give it that touch of fighter jet style.

Heads-up displays use the small reflectivity of a transparent surface to work. In this case, [Frank] uses an LED strip placed on the dashboard to shine up into the windshield. A small amount of light is reflected back to the driver which is able to communicate vehicle statues without obscuring view of the road. [Frank]’s system is able to display information reported over the CAN bus, including voltage, engine RPM, and speed.

This display seems to account for all the issues we could think up. It automatically cycles through modes depending on driving style (revving the engine at a stoplight switches it to engine RPM mode, for example), the LEDs automatically dim at night to avoid blinding the driver, and it interfaces with the CAN bus which means the ability to display any other information in the future should be relatively straightforward. [Frank] does note some rough edges, though, namely with the power supply and the fact that there’s a large amount of data on the CAN bus that the Teensy microcontroller has a hard time sorting out.

That being said, the build is well polished and definitely adds a fighter jet quality to the car. And if [Frank] ever wants even more aviation cred for his ground transportation, he should be able to make use of a 747 controller for something on the dashboard, too.