raspberry pi

1647 Articles

IOT Message Board Puts Fourteen-Segment Displays To Work

March 28, 2023 by 4 Comments

We’re not sure, but the number of recognizable alphanumeric characters that a seven-segment display can manage seems to have more to do with human pattern recognition than engineering. It takes some imagination, and perhaps a little squinting, to discern some characters, though. Arguably better is the fourteen-segment display, which has been pressed into service in this just-for-funsies IOT message board.

As [Steve] tells the story, this is one of those “boredom-buster” projects that start with a look through the junk bin to see what presents itself. In his case, some fourteen-segment common-cathode LEDs presented themselves, and the result was a simple but fun build. [Steve] used some clever methods to get the display stuffed onto two protoboards, including mounting the current-limiting resistors cordwood-style between the boards. A Raspberry Pi drives the display through a very neatly routed ribbon cable, and the whole thing lives in a tidy wooden box.

The IOT part of the build allows the display to show messages entered on [Steve]’s web page, with a webcam live stream to close the loop. Strangely, the display seems stuck on the “HI HACKADAY!” we entered as a test after [Steve] tipped us off, so we’re not sure if we busted it or what. Apologies if we did, [Steve]. And by the way, if your cats are named [Nibble] and [Pixel], well done!

No matter what you do with them, multi-segment displays are pretty cool. But if you think they’re something new, you’ve got another think coming.

A picture of the bottom of the Pi 4 PCB, showing the three points you need to use to tap into the Pi 4 I2C bus going to the PMIC

Dead Raspberry Pi Boards, PMICs, And New Hope

March 24, 2023 by 22 Comments

Since the Raspberry Pi 3B+ release, the Pi boards we all know and love gained one more weakpoint – the PMIC chip, responsible for generating all the power rails a Pi needs. Specifically, the new PMIC was way more vulnerable to shorting 5V and 3.3V power rails together – something that’s trivial to do on a Raspberry Pi, and would leave you with a bricked board. Just replacing the PMIC chip, the MxL7704, wouldn’t help since the Raspberry Pi version of this chip is customized – but now, on Raspberry Pi forums, [Nefarious19] has reportedly managed to replace it and revive their Pi.

First off, you get a replacement PMIC and reflow it – and that’s where, to our knowledge, people have stopped so far. The next step proposed by [Nefarious19] is writing proper values into the I2C registers of the PMIC. For that, you’d want a currently-alive Pi – useful as both I2C controller for writing the values in, and as a source of known-good values. That said, if you go with the values that have been posted online, just having something like a Pi Pico for the I2C part ought to be enough.

[Nefarious19] reports a revived Pi, and this is way more hopeful than the “PMIC failures are unfixable” conclusion we’ve reached before. The instructions are not quite clear – someone else in the thread reports an unsuccessful attempt doing the same, and it might be that there’s a crucial step missing in making the values persist. However, such an advancement is notable, and we trust our readers to take the lead.

A week ago, [Mangy_Dog] on Hackaday Discord brought up fixing Raspberry Pi boards – given that the Raspberry Pi shortages are still an issue, digging up your broken Pi and repairing it starts making sense budget-wise. It’s no longer the ages where you could buy broken Pi boards by the hundred, and we imagine our readers have been getting creative. What are your experiences with fixing Raspberry Pi boards?

Dobsonian Telescope Adds Plate Solver

March 16, 2023 by 27 Comments

The amateur astronomy world got a tremendous boost during the 1960s when John Dobson invented what is now called the Dobsonian telescope. Made from commonly-sourced materials and mechanically much simpler than what was otherwise available at the time, the telescope dramatically reduced the barrier to entry for larger telescopes and also made them much more portable and inexpensive.

For all their perks, though, a major downside is increased complexity when building automatic tracking systems. [brickbots] went a different way when solving this problem, though: a plate solver.

Plate solving is a method by which the telescope’s field of view is compared to known star charts to determine what it’s currently looking at. Using a Raspberry Pi at the center of the build, the camera module pointed at the sky lets the small computer know exactly what it’s looking at, and the GPS system adds precise location data as well for a quick plate solving solution. A red-tinted screen finishes out the build and lets [brickbots] know exactly what the telescope is pointed towards at all times.

While this doesn’t fully automate or control the telescope like a tracking system would do, it’s much simpler to build a plate solver in this situation. That doesn’t mean it’s impossible to star hop with a telescope like this, though; alt-azimuth mounted telescopes like Dobsonians just need some extra equipment to get this job done. Here’s an example which controls a similar alt-azimuth telescope using an ESP32 and a few rotary encoders.

Raspberry Pi Adds Second Laptop Monitor

March 15, 2023 by 17 Comments

If you have a cheap laptop and you realize you can’t connect a second monitor to it, what do you do? Well, if you are [Pierre Couy], you grab a Raspberry Pi and put together a virtual screen solution.

Like all good projects, this one started with some goals and requirements:

  • Low latency
  • Redable text
  • At least 10 frames per second
  • Fast catch up if the remote screen falls behind
  • Low-bitrate encoding; no hardware acceleration
  • A DHCP server on the Pi to manage the network
  • Power control for the attached monitor

Continue reading “Raspberry Pi Adds Second Laptop Monitor” →

Mice Play In VR

March 14, 2023 by 9 Comments

Virtual Reality always seemed like a technology just out of reach, much like nuclear fusion, the flying car, or Linux on the desktop. It seems to be gaining steam in the last five years or so, though, with successful video games from a number of companies as well as plenty of other virtual reality adjacent technology that seems to be picking up steam as well like augmented reality. Another sign that this technology might be here to stay is this virtual reality headset made for mice. Continue reading “Mice Play In VR” →

Mechanical Keyboard As Travel Saxophone

March 14, 2023 by 9 Comments

Those who play larger musical instruments, things like drums, piano, harp, tuba, upright bass, or Zeusaphone, know well the challenges of simply transporting their chosen instrument to band practice, a symphony hall, or local watering hole. Even those playing more manageably-sized instruments may have similar troubles at some point especially when traveling where luggage space is at a premium like on an airplane. That’s why [jcard0na] built this electronic saxophone, designed to be as small as possible.

Known as the “haxophone”, the musical instrument eschews the vibrating column of air typical of woodwind instruments in favor of an electronic substitute. Based around the Raspberry Pi, the device consists of a custom HAT with a number of mechanical keyboard switches arrayed in a way close enough to the layout of a standard saxophone that saxophonists will be able to intuitively and easily play. Two pieces of software run on the Pi to replicate the musical instrument, one that detects the player’s breaths and key presses, and another that synthesizes this information into sound.

While [jcard0na] notes that this will never replicate the depth and feel of a real instrument, it does accomplish its design goal of being much more easily transportable than all but the most soprano of true saxophones. As a musical project it’s an excellent example of good design as well, much like this set of electronic drums with a similar design goal of portability.

Classic Gaming With FPGA And ATX

March 14, 2023 by 5 Comments

Playing classic games, whether they are games from the golden age of arcades or simply games from consoles that are long out of production, tends to exist on a spectrum. At one end is grabbing a game’s ROM file, finding an emulator, and kludging together some controls on a keyboard and mouse with your average PC. At the other is meticulously restoring classic hardware for the “true” feel of what the game would have felt like when it was new. Towards the latter end is emulating the hardware with an FPGA which the open-source MiSTer project attempts to do. This build, though, adds ATX capabilities for the retrocomputing platform. Continue reading “Classic Gaming With FPGA And ATX” →