Bullet Time On A Budget With The Raspberry Pi

October 2, 2020 by Lewin Day 24 Comments

Bullet time became the hottest new cinema effect after it burst on the scene in The Matrix (1999). Back then, the cutting edge special effects required serious hardware and serious processing power to do the job. These days, of course, things have moved along somewhat. [Eric Paré] is no stranger to a high-end setup, but wanted to see what could be done at the lower end of the market. (Video, embedded below.)

Rather then relying on a bank of expensive DSLRs, [Eric] decided to try building a bullet-time camera rig out of 15 Raspberry Pis, and the standard Raspberry Pi Camera. Whereas just one camera in one of his professional setups may cost well over $1000, this entire rig was likely built for less than that in its entirety.

Initial results were jerky and unappealing, but [Eric] persevered. One of the biggest problems was inaccuracy in the camera assemblies, as they were stuck on with thermal paste. With some custom mods and tweaks, [Eric] was eventually able to get things to a passable state. It also has the benefit, compared to a DSLR rig, that the cameras can be mounted much more closely together due to their small size.

Work is already underway to upgrade the rig to the new Raspberry Pi HQ Camera, which we’ve discussed before.

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Raspberry Pi Helps Racer Master The Track

October 1, 2020 by Tom Nardi 9 Comments

Looking to give himself a competitive edge, racer [Douglas Hedges] wanted to come up with a system that could give him real-time feedback on how his current performance compared to his previous fastest lap time. Armed with a Raspberry Pi and some Python libraries, he set out to add a simple telemetry system to his car. But as is often the case with these kind of projects, things just started snowballing from there.

The Raspberry Pi based data acquisition system.

At the most basic level, his system uses GPS position and speed information to light up a strip of RGB LEDs on the dashboard: green means he’s going faster than the previous best lap, and red means he isn’t. Any interface more complex than that would just be a distraction while he focuses on the track. But that doesn’t mean the Raspberry Pi can’t collect data for future review after the race is over.

With the basic functionality in place, [Douglas] turned his attention to collecting engine performance data. It turned out the car already had some pre-existing equipment for collecting metrics such as the air-fuel ratio and RPM, which he was able to connect to the Raspberry Pi thanks to its use of a well documented protocol. On top of that he added a Labjack U3 data acquisition system which let him pull in additional information like throttle position and coolant temperature. Grafana is used to visualize all of this data after the race, though it sounds like he’s also considering adding a cellular data connection vehicle data can be streamed out in real-time.

In the past we’ve seen onboard data collection systems make real-world races look more like their virtual counterparts, but it seems like the solution [Douglas] has come up with is more practical in the heat of the moment.

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3D Printed Video Terminal Dials C For Cyberpunk

October 1, 2020 by Tom Nardi 8 Comments

Created for the Disobey 2020 hacker conference in Finland, this Blade Runner inspired communications terminal isn’t just for decoration. It was part of an interactive game that required attendees to physically connect their conference badges up and “call” different characters with the functional keypad on the front of the unit.

[Purkkaviritys] was in charge of designing the 3D printed enclosure for the device, which he says takes an entire 2 kg roll of filament to print out. Unfortunately he wasn’t as involved in the electronics side of things, so we don’t have a whole lot of information about the internals beyond the fact that its powered by a Raspberry Pi 4, features a HyperPixel 4.0 display, and uses power over Ethernet so it could be easily set up at the con with just a single cable run.

The keypad is a custom input device using the Arduino Micro and Cherry MX Blue switches with 3D printed keycaps to get that chunky payphone look and feel. [Purkkaviritys] mentions that the keypad is also responsible for controlling the RGB LED strips built into the sides of the terminal, and that the Raspberry Pi toggles the status of the Caps, Scroll Lock, and Num Lock keys to select the different lighting patterns.

Naturally we’d like to see more info on how this beauty was put together, but given that it was built for such a specific purpose, it’s not like you’d really need to duplicate the original configuration anyway. Thanks to [Purkkaviritys] you have the STL files to print off our own copy of the gloriously cyberpunk enclosure, all you’ve got to do now is figure out how to make video calls with it.

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KiwiSDR Vs RaspberrySDR — A Tale Of Two SDRs

September 30, 2020 by Al Williams 45 Comments

Once you move away from the usual software defined radio (SDR) dongles, you have only a few choices unless you want to drop some serious cash. One common hobby-grade SDR is the KiwiSDR. This popular unit runs Linux and can receive up to 30 MHz. The platform uses a dedicated A/D converter, an FPGA, and BeagleBone computer. Success of course breeds imitators, and especially when you have an open source design like the Kiwi, you are going to find similar devices with possibly different end goals. That’s how the RaspberrySDR came to be. This is a very similar unit to the KiwiSDR but it uses a Raspberry Pi, along with a handful of other differences. What’s different? [KA7OEI] tells us in a recent blog post.

Other than the obvious difference of the computer and all that it entails, the RaspberrySDR has a higher speed A/D (125 MHz vs 66 MHz) and 16-bits of resolution instead of the Kiwi’s 14 bits. This combines to give the Raspberry a wider receive range (up to 60 MHz) and — in theory — better performance in terms of dynamic range and distortion.

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An Elegant Modular Enclosure System For The Raspberry Pi 4

September 28, 2020 by Danie Conradie 45 Comments

[NODE] has been experimenting with Raspberry Pi servers and mini computers for a long time, and knows all too well how the wiring can quickly turn into a rat’s nest. His latest creation is the Mini Server version 3, a modular enclosure system for the Raspberry Pi 4, is designed to turn it into practical computing box.

The basic enclosure is a 92 mm x 92 mm x 26 mm 3D printed frame with a custom PCB top cover. One of the main goals was to collect all the major connectors on one side and make the micro SD slot easily accessible. To do this [NODE] created a set of custom PCB adaptors to route the USB-C and an HDMI port to the same side as the other USB ports, and move the micro SD slot to the bottom of the enclosure. A low profile adaptor was also designed to connect a mSATA SSD to one of the USB 3 ports, and there is space inside the enclosure for one or two cooling fans. Unlike previous version of the mini server, no hardware modifications are required on the Pi itself.

The only downside that we can see is that it doesn’t allow external access to the GPIO ports, but the entire project is open source specifically to allow people to make their own modifications.

[NODE] is a big fan of turning Raspberry Pis into custom computing devices, ranging from small terminal devices and pocket servers, to complete laptops.

Internet Connected E-Paper Message Board

September 25, 2020 by Rich Hawkes 16 Comments

Are you still writing notes on paper and sticking them to the fridge like it’s the ’80s? Well, if you are, and you read this site, you’d probably like to upgrade to something a bit more 21st century. And, thanks to robot maker [James Bruton], you can leave your old, last century, message taking behind as he has a tutorial up showing you how to build an internet connected e-paper message display board. And, if you have a Raspberry Pi, an e-paper display and adapters just lying around doing nothing, then this project will cost you less than the buck that paper and a magnet will cost you.

Sarcasm aside, this is a pretty nice project. As mentioned, the base of this is a Raspberry Pi – [James] uses a Pi 4, but you could get away with an older, lower powered model as well. This powers the cheap(-ish) e-paper display he found online, which comes with the necessary adapters for the Pi, as well as a python library to write to the display. [James] uses a Google Sheet as the cloud storage for the message board, and there is some python code to access the cells in the Sheet and print them on the display if anything has changed. A cron job runs the script every 5 minutes to catch changes in the messages.

As with most of the projects that [James] does, he gives a good overview in the video and goes over the process of finding the hardware and writing and updating the script. He’s put the script and details as well as the CAD file for the frame he created for the project up on GitHub. [James] has been featured several times on the site before, check out some of his projects.

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Adding MIDI To A Mini Synth Is Easy As Pi

September 21, 2020 by Kristina Panos 11 Comments

There are a handful of relatively dirt cheap synths out there like the KORG Monotron, but many of them use ribbon controllers that aren’t very precise. Ribbon controllers basically slide pots that you operate with your finger or a stylus. They’re painted to look like piano keys in order to show you approximately where the notes are supposed to be. The Stylophone is another extremely affordable synth that does even less as a synthesizer and uses this type of input. It’s a fun input if you don’t mind imprecision, but can be annoying otherwise.

[schollz] isn’t satisfied to synth this way, so they added MIDI input to their KORG Monotron using a Raspberry Pi and a DAC. Fortunately, the Monotron is quite the hackable little synth, with nice, big, labelled pads on the PCB.

All it really took was a couple of solder joints in the right places, plus a clever Python script. The script listens for MIDI input from a keyboard, and then controls an MCP4725 DAC, which sends voltages to the Monotron. [schollz] wrote a tuning function that computes the FFT of the MIDI tones to find the fundamental frequencies of each to send along to the Monotron. Check it out after the break.

If liquid control is what you’re after but all you have is a keyboard, try making your own ribbon controller.

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