PCB Mods Silence Voltage Warnings On The Pi 4

February 12, 2021 by Tom Nardi 122 Comments

If you’ve ever pushed the needle a bit on your Raspberry Pi, there’s a good chance you’ve been visited by the dreaded lightning bolt icon. When it pops up on the corner of the screen, it’s a warning that the input voltage is dipping into the danger zone. If you see this symbol often, the usual recommendation is to get a higher capacity power supply. But experienced Pi wranglers will know that the board can still be skittish.

Sick of seeing this icon during his MAME sessions, [Majenko] decided to attack the problem directly by taking a close look at the power supply circuitry of the Pi 4. While the official schematics for everyone’s favorite single-board computer are unfortunately incomplete, he was still able to identify a few components that struck him as a bit odd. While we wouldn’t necessarily recommend you rush out and make these same modifications to your own board, the early results are certainly promising.

The first potential culprit [Majenko] found was a 10 ohm resistor on the 5 V line. He figured this part alone would have a greater impact on the system voltage than a dodgy USB cable would. The components aren’t labeled on the Pi’s PCB, but with a little poking of the multimeter he was able to track down the 0402 component and replace it with a tiny piece of wire. He powered up the Pi and ran a few games to test the fix, and while he definitely got fewer low-voltage warnings, there was still the occasional brownout.

Going back to the schematic, he noticed there was a 10 uF capacitor on the same line as the resistor. What if he bumped that up a bit? The USB specifications say that’s the maximum capacitive load for a downstream device, but he reasoned that’s really only a problem for people trying to power the Pi from their computer’s USB port.

Tacking a 470 uF electrolytic capacitor to the existing SMD part might look a little funny, but after the installation, [Majenko] reports there hasn’t been a single low-voltage warning. He wonders if the addition of the larger capacitor might make removing the resistor unnecessary, but since he doesn’t want to mess with a good thing, that determination will be left as an exercise for the reader.

It’s no secret that the Raspberry Pi 4 has been plagued with power issues since release, but a newer board revision released last year helped smooth things out a bit. While most people wouldn’t go this far just to address the occasional edge case, it’s good to know folks are out there experimenting with potential fixes and improvements.

Stay Focused With This Distraction Free Cyberdeck

February 9, 2021 by Tom Nardi 15 Comments

While on the surface they might seem like little more than cosplay accessories, there are perfectly valid and practical reasons for building a custom cyberdeck. For one thing, a hand-built deck is going to be easier to upgrade and modify down the line. A bespoke rig can also be made to fit your exacting specifications, with each and every design choice made specifically to support your personal style and workflow.

For [Conrad Barski], that meant a computer that would stay out of his way and allow him to take notes and write code while keeping distractions to the absolute minimum. All he wanted in his dream machine was a nice mechanical keyboard, a widescreen display, and enough battery power to go mobile should the need arise. Anything else would be gilding the lily. For those who want to distill personal computing down to its simplest form, this build is really the high water mark.

[Conrad] is currently in the early stages of turning his Lisperati1000 into a kit others can build for themselves, so details are a bit sparse at the moment. But we do know there’s a Raspberry Pi Zero W, a Vortex Core 40% keyboard, and 4,400 mAh worth of battery power wrapped up in that slick 3D printed enclosure. Readers may recognize the 1920×480 ultra-wide LCD from the modernized TRS-80 Model 100 we covered recently, or perhaps the gorgeously reimagined retro terminals of [Oriol Ferrer Mesià]. If you’ve got retro-futurism on the brain, this seems to be the display to beat.

Whether you want to explore vintage computing, stylishly take control of your custom race car, or cruise the airwaves with an integrated software defined radio, a completely custom portable computing device can make for an interesting alternative to another ho-hum laptop from the Big Box electronics store.

Interfacing A Z80 CPU With The Raspberry Pi

February 9, 2021 by Lewin Day 25 Comments

The Z80 was a big deal in the 1970s and 1980s, and while its no longer a dominant architecture today, its legacy lives on. [James Andrew Fitzjohn] is a fan of the Z, and decided to interface the real silicon with the Raspberry Pi, by and large for the fun of it!

The Z80’s address and data lines, as well as the clock, are hooked up to the Raspberry Pi through several MCP23017 GPIO expanders. The Pi’s GPIO lines aren’t known for their speed, of course, and using expanders through I2C isn’t exactly quick either. However, speed isn’t necessary, as the clock only goes as fast as the Raspberry Pi desires, since it’s controlling the clock along with everything else. There’s also an LCD for viewing the Z80s status, along with some era-appropriate blinkenlights.

This setup allows the Pi to run code directly on the Z80 itself, while managing the CPU’s RAM in its own memory, all through a Python script. It’s a fun hack that lets you run retro code on retro silicon without using an emulator. Techniques like these are useful for finding undocumented or edge case performance of a processor. If this hack isn’t enough Zilog for your liking, consider throwing one in your pocket as well!

Raspberry Pi Takes Over Volvo’s Integrated LCD

February 5, 2021 by Tom Nardi 11 Comments

As [Luuk Esselbrugge] explains in a recent blog post, his 2002 Volvo S60 had an optional GPS navigation system and backup camera that used a motorized display that would rise out of the dashboard when needed. His particular car didn’t come with the hardware installed, but after getting his hands on a display module and doing some research, he figured out how he could drive it with the Raspberry Pi and a couple of microcontrollers.

Given the age of the display, you probably won’t be surprised to hear that it uses composite video. Not exactly high resolution, but in the demonstration after the break, we have to admit it looks more than up to the task. [Luuk] is running Android Auto on the Raspberry Pi 3 through the openauto project, which gives him a nice big display and access to all the navigation and media applications you’d expect. The display doesn’t support touch, but thanks to an ESP32 plugged into the CAN bus, he’s able to control the software by reading the buttons built into the Volvo’s steering wheel.

Composite video sources are switched with a simple relay.

To actually raise and lower the display, [Luuk] found you just need to fire a few bytes down the 1,200 baud serial bus that’s built into the display’s wiring harness. The ESP32 handles this duty as well, at least partly because it’s already plugged into the CAN bus and can tell when the vehicle is in reverse. This lets it bring up the screen to show the video feed from the newly installed backup camera in the event that the Pi hadn’t already asked to raise the display. Incidentally plugging in the phone normally triggers the system to wake up and raise the screen, and disconnecting it will command the screen to lower back into the stowed position.

The attentive reader or Volvo aficionado may be wondering how [Luuk] got the audio working. Since his car’s sound system doesn’t feature an auxiliary input, he’s using an Arduino to spoof the existence of a CD changer, which allows him to inject an audio signal into one of the pins on the back of the radio. Eventually he wants to move this task over to the ESP32, but he says a big change like that will have to wait until warmer weather.

This isn’t the first time we’ve seen the Raspberry Pi used to add enhanced features to a somewhat older vehicle. While some bemoan the increased complexity of modern vehicles, it seems some hackers can’t get enough of it.

Continue reading “Raspberry Pi Takes Over Volvo’s Integrated LCD” →

A Look At The Interesting RP2040 Peripheral, Those PIOs

January 29, 2021 by Jenny List 41 Comments

The Raspberry Pi Pico is the latest product in the Raspberry Pi range, and it marks a departure from their previous small Linux-capable boards. The little microcontroller board will surely do well in the Pi Foundation’s core markets, but its RP2040 chip must have something special as a commercial component to avoid being simply another take on an ARM microcontroller that happens to be a bit more expensive and from an unproven manufacturer in the world of chips. Perhaps that special something comes in its on-board Programable IO perhipherals, or PIOs. [CNX Software] have taken an in-depth look at them, which makes for interesting reading.

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Raspberry Pi Zero Powers Spotify Streaming IPod

January 27, 2021 by Tom Nardi 32 Comments

Even those critical of Apple as a company have to admit that they were really onto something with the iPod. The click wheel was a brilliant input device, and the simplicity of the gadget’s user interface made it easy to get to the music you wanted with a minimum of hoop jumping. Unfortunately it was a harbinger of proprietary software and DRM, but eventually there were a few open source libraries that let you put songs on the thing without selling your soul to Cupertino.

Of course, modern users expect a bit more than what the old hardware can deliver. Which is why [Guy Dupont] swapped the internals of his iPod Classic with a Raspberry Pi Zero W. This new Linux-powered digital audio player is not only capable of playing essentially any audio format you throw at it, but can also tap into streaming services such as Spotify. But such greatness doesn’t come easy; to pull this off, he had to replace nearly every component inside the player with the notable exception of the click wheel itself. Good thing the Classics were pretty chunky to begin with.

In addition to the Pi Zero running the show, he also had to fit a 1000 mAh battery, its associated charging and boost modules, a vibration motor for force feedback, and a 2″ LCD from Adafruit. The display ended up being almost the perfect size to replace the iPod’s original screen, and since it uses composite video, only took two wires to drive from the Pi. To interface with the original click wheel, [Guy] credits the information he pulled from a decade-old Hackaday post.

Of course with a project like this, the hardware is only half the story. It’s one thing to cram all the necessary components inside the original iPod enclosure, but by creating such an accurate clone of its iconic UI in Python, [Guy] really took things to the next level. Especially since he was able to so seamlessly integrate support for Spotify, a feature the Apple devs could scarcely have imagined back at the turn of the millennium. We’re very interested in seeing the source code when he pushes it to the currently empty GitHub repository, and wouldn’t be surprised if it set off a resurgence of DIY iPod clones.

We’ve seen modern hardware grafted onto the original iPod mainboard, and over the years a few hackers have tried to spin up their own Pi-based portable music players. But this project that so skillfully combines both concepts really raises the bar.

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Repairing 200+ Raspberry Pis For A Good Cause

January 25, 2021 by Tom Nardi 37 Comments

If somebody told you they recently purchased over 200 Raspberry Pis, you might think they were working on some kind of large-scale clustering project. But in this case, [James Dawson] purchased the collection of broken single-board computers with the intention of repairing them so they could be sent to developing countries for use in schools. It sounds like the logistics of that are proving to be a bit tricky, but we’re happy to report he’s at least made good progress on getting the Pis back up and running.

He secured this trove of what he believes to be customer returned Raspberries or the princely sum of £61 ($83 USD). At that price, even if only a fraction ended up being repairable, you’d still come out ahead. Granted all of these appear to be the original Model B, but that’s still a phenomenal deal in our book. Assuming of course you can find some reasonable way to triage them to sort out what’s worth keeping.

To that end, [James] came up with a Bash script that allowed him to check several hardware components including the USB, Ethernet, I2C, and GPIO. With the script on an SD card and a 3.5″ TFT plugged into the Pi’s header for output, he was able to quickly go through the box to get an idea of what sort of trouble he’d gotten himself into. He was only about half way through the process when he wrote this particular blog post, but by that point, he’d found just 40 Pis which wouldn’t start at all. He suspects these might be victims of some common issue in the power circuitry that he’ll investigate at a later date.

A metal ruler made short work of bent pins.

A nasty, but repairable, problem.

The majority of Pis he checked were suffering from nothing worse than some bent GPIO pins or broken SD card slots. Some of the more abused examples had their USB ports ripped off entirely, but were otherwise fine. Another 10 had dead Ethernet, and 4 appear to have damaged traces leading to their HDMI ports. While we’re interested in hearing if [James] can get those 40 dark Pis to fire back up, so far the results are quite promising.

Donating hardware is always a tricky thing, so for now [James] says he’ll be selling the repaired Pis on eBay and donating the proceeds to the Raspberry Pi Foundation so they can continue to develop hardware that will (potentially) accomplish their goal of giving students all over the world a functional computer.