An AMD GPU plugged into an ATX PSU and Raspberry PI CM4

Raspberry Pi With Some Serious Graphical Muscle

September 20, 2021 by Matthew Carlson 12 Comments

[Jeff Geerling] routinely tinkers around with Raspberry Pi compute module, which unlike the regular RPi 4, includes a PCI-e lane. With some luck, he was able to obtain an AMD Radeon RX 6700 XT GPU card and decided to try and plug it into the Raspberry Pi 4 Compute Module.

While you likely wouldn’t be running games with such as setup, there are many kinds of unique and interesting compute-based workloads that can be offloaded onto a GPU. In a situation similar to putting a V8 on a lawnmower, the Raspberry Pi 4 pulls around 5-10 watts and the GPU can pull 230 watts. Unfortunately, the PCI-e slot on the IO board wasn’t designed with a power-hungry chip in mind, so [Jeff] brought in a full-blown ATX power supply to power the GPU. To avoid problems with differing ground planes, an adapter was fashioned for the Raspberry Pi to be powered from the PSU as well. Plugging in the card yielded promising results initially. In particular, Linux detected the card and correctly mapped the BARs (Base Address Register), which had been a problem in the past for him with other devices. A BAR allows a PCI device to map its memory into the CPU’s memory space and keep track of the base address of that mapped memory range.

AMD kindly provides Linux drivers for the kernel. [Jeff] walks through cross-compiling the kernel and has a nice docker container that quickly reproduces the built environment. There was a bug that prevented compilation with AMD drivers included, so he wasn’t able to get a fully built kernel. Since the video, he has been slowly wading through the issue in a fascinating thread on GitHub. Everything from running out of memory space for the Pi to PSP memory training for the GPU itself has been encountered.

The ever-expanding capabilities of the plucky little compute module are a wonderful thing to us here at Hackaday, as we saw it get NVMe boot earlier this year. We’re looking forward to the progress [Jeff] makes with GPUs. Video after the break.

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Supercapacitors For The Raspberry Pi

October 4, 2014 by Bryan Cockfield 45 Comments

As versatile as the Raspberry Pi is, it has a weakness when it needs to be able to shut down properly during a power outage, especially when handling data-sensitive or industrial applications. To solve this problem, [Pavol Sedlacek] has created a supercapacitor-based UPS specifically for the Raspberry Pi that gives it enough time to properly halt its processes and shut down if it detects a power failure.

The device is called the Juice4Halt. It uses a DC-DC converter to provide power to the Pi from the normal power supply and to charge the supercapacitors during normal operation. It is bidirectional, so in the event of a power failure it works in reverse to take power from the capacitors and feed it back to the Pi. A second DC-DC converter handles power from an external power supply.

A side effect of using supercapacitors as a UPS is that they can also help the Pi survive brownouts. The project site has an incredible amount of detail about the functionality of the device, including circuit diagrams and the source code. We’ve seen other supercapacitor-based UPS units before but this particular one is much more robust and would be truly at home in any industrial or other sensitive setting.

A Real Raspberry Pi Clone (Not ‘Inspired By’)

July 30, 2014 by Brian Benchoff 63 Comments

odroid A few years ago, Broadcom had a pretty nice chip – the BCM2835 – that could do 1080 video, had fairly powerful graphics performance, run a *nix at a good click, and was fairly cheap. A Broadcom employee thought, “why don’t we build an educational computer with this” and the Raspberry Pi was born. Since then, Broadcom has kept that chip to themselves, funneling all of them into what has become a very vibrant platform for education, tinkering, and any other project that could use a small Linux board. Recently, Broadcom has started to sell the BCM2835 to anyone who has the cash and from the looks of it, real Raspberry Pi clones are starting to make their way into the marketplace.

Other Raspberry Pi clone boards out there like the Banana Pi and the HummingBoard don’t use the same BCM2835 found in the Raspi and the new Odroid. The new board also has the same 26 pin GPIO expansion socket, and runs the same binaries as the Raspberry P;. It is a clone in every sense, with a slightly different form factor geared towards very tiny, portable, and battery-powered use cases.

Unlike the official Raspberry Pi Compute Module, the Odroid isn’t meant to be used as a system on module, shoved into any product that needs a fast-ish ARM core without needing engineers to actually design a circuit with an ARM. The Odroid is a cut-down, extremely minimalist version of the Raspi, perfect for any project where space is at a premium.

There are a few interesting features included on the Odroid: there’s an on-board battery connector, a real-time clock on the board, and more of the BCM2835 GPIOs are exposed (although not the same ones as the upgraded RPi Model B+). There’s no Ethernet, but odds are if you’re building something that’s battery-powered, you won’t need that anyway.

As far as price goes, you can pick one of these Odroids up for $30 USD, with $9 shipping from South Korea. That’s pretty comparable to the price of a real Raspberry Pi, but if the features in the Odroid are worth it to you, it might be a worthwhile clone.

Raspberry Pi UPS Using Supercapacitors

April 3, 2014 by James Hobson 21 Comments

What happens when you want to integrate a Raspberry Pi into some kind of project that gets turned on and off with mains voltage? Do you power the Pi separately, or make a UPS for it?

[Lutz Lisseck] decided he wanted to turn his ambient-lamp (Rundbuntplasma) on and off with only the main power switch in his Hackerpsace. He could build a traditional UPS using a battery pack (it’s only 5V after all!) but decided to take it a step further. He picked up a pair of 50F supercapacitors. This way his UPS would last longer than his Pi would! The caps store just enough power that when the main supply is cut, a GPIO notices, tells the Pi, and it begins a shutdown sequence lasting about 30 seconds.

While [Lutz] is using two 2.7V supercapacitors, he mentions it would be a lot cheaper to use a step-up converter instead of putting them in series — but he had the caps on hand so decided to use both.

If you need it to last a bit longer, you could make one with rechargeable batteries…

40-Node Raspi Cluster

February 17, 2014 by Marsh 48 Comments

Multi-node RasPi clusters seem to be a rite of passage these days for hackers working with distributed computing. [Dave’s] 40-node cluster is the latest of the super-Pi creations, and while it’s not the biggest we’ve featured here, it may be the sleekest.

The goal of this project—aside from the obvious desire to test distributed software—was to keep the entire package below the size of a full tower desktop. [Dave’s] design packs the Pi’s in groups of 4 across ten individual cards that easily slide out for access. Each is wired (through beautiful cable management, we must say) to one of the 2 24-port switches at the bottom of the case. The build uses an ATX power supply up top that feeds into individual power for the Pi’s and everything else, including his HD array—5 1TB HD’s, expandable to 12—a wireless router, and a hefty fan assembly.

Perhaps the greatest achievement is the custom acrylic case, which [Dave] lasered out at the Dallas Makerspace (we featured it here last month). Each panel slides off with the press of a button, and the front/back panels provide convenient access to the internal network via some jacks. If you’ve ever been remotely curious about a build like this one, you should cruise over to [Dave’s] page immediately: it’s one of the most meticulously well-documented projects we’ve seen in a long time. Videos after the break.

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Self-Balancing Robot Keeps Getting More Features

November 10, 2013 by Mike Szczys 18 Comments

self-balancing-robot-gets-more-features

It’s a lot of fun to see a self-balancing robot project. Rarely do they go much further than being able to keep themselves upright while being piloted remotely and annoyingly shoved by their creator as proof of their ability to remain standing on two wheels. This little anthropomorphic guy is the exception to the rule. It’s the product of [Samuel Matos] who says he didn’t have a specific purpose in mind, but just kept adding features as they came to him.

Starting with a couple of carbon fiber plates [Samuel] cut the design by hand, using stand-offs to mount the NEMA 17 stepper motors and to connect the two halves of the chassis. It looks like he used some leftover material to make a nice little stand which is nice when coding at his desk as seen above. There’s also a carbon-fiber mask which makes up the face atop an articulated neck. It has two ultrasonic range-finding sensors as eyes, and the Raspberry Pi camera module as the nose. The RPi board powerful enough to run OpenCV which has kept [Samuel] busy. He set up a course in his living room containing tags directing where the little guy should go. It can also follow a tennis ball as it rolls around the room. What we found most impressive in the clip after the break is its ability to locate the next tag after making a turn.

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Web Connectivity And Other Addons For An Automatic Schnauzer Feeder

September 8, 2013 by Mike Szczys 9 Comments

web-enabled-automatic-dog-feeder

[Ben Miller] and his dad combined forces to create this automatic dog feeder. It not only keeps their two schnauzers happy, but gives them peace of mind as they can double-check that he feeding happened by pulling up an image on the Internet. Make sure you make it through all three posts of the build to get the entire picture.

The project started with some research which turned up a project that used a commercially available automatic feeder. That one used Arduino, but because of the cost the board plus a WiFi shield is a bit high, [Ben] went with a Raspberry Pi and a USB WiFi dongle instead. The Pi is much more powerful and adds the functionality for capturing images via a webcam.

After a convoluted process of connecting the Pi to the existing button traces on the automatic feeder it was time to start coding. The system runs from a Perl script which monitors a Gmail account for remote commands (in addition to a regular feeding schedule). The final touch is a bit of mechanical engineering which splits the output into two bowls so the dogs each have their own serving.

We still use the Autodine we built several years back but its single-serving limitation has always kept a second version on our project list. Hopefully seeing a well-executed system like this will motivate us to get building!