Raspberry Pi Hat Adds SDR With High Speed Memory Access

An SDR add-on for the Raspberry Pi isn’t a new idea, but the open source cariboulite project looks like a great entry into the field. Even if you aren’t interested in radio, you might find the project’s use of a special high-bandwidth memory interface to the Pi interesting.

The interface in question is the poorly-documented SMI or Secondary Memory Interface. [Caribou Labs] helpfully provides links to others that did the work to figure out the interface along with code and a white paper. The result? Depending on the Pi, the SDR can exchange data at up to 500 Mbps with the processor. The SDR actually uses less than that, at about 128 Mbps. Still, it would be hard to ship that much data across using conventional means.

On the radio side, the SDR covers 389.5 to 510 MHz and 779 to 1,020 MHz. There’s also a wide tuning channel from 30 MHz to 6 GHz, with some exclusions. The board can transmit at about 14 dBm, depending on frequency and the receive noise figure is under 4.5 dB for the lower bands and less than 8 dB above 3,500 MHz. Of course, some Pis already have a radio, but not with this kind of capability. We’ve also seen SMI used to drive many LEDs.

Where Are All The Cheap X86 Single Board PCs?

If we were to think of a retrocomputer, the chances are we might have something from the classic 8-bit days or maybe a game console spring to mind. It’s almost a shock to see mundane desktop PCs of the DOS and Pentium era join them, but those machines now form an important way to play DOS and Windows 95 games which are unsuited to more modern operating systems. For those who wish to play the games on appropriate hardware without a grubby beige mini-tower and a huge CRT monitor, there’s even the option to buy one of these machines new: in the form of a much more svelte Pentium-based PC104 industrial PC.

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TV Ambient Lighting Built For Awesome Performance

[AndrewMohawk] had seen all kinds of ambient lighting systems for TVs come and go over the years, and the one thing they all had in common was that they didn’t live up to his high standards. Armed with the tools of the hacker trade, he set about building an Ambilight-type system of his own that truly delivered the goods.

The development process was one full of roadblocks and dead ends, but [Andrew] persevered. After solving annoying problems with HDCP and HDMI splitters, he was finally able to get a Raspberry Pi to capture video going to his TV and use OpenCV to determine the colors of segments around the screen. From there, it was simple enough to send out data to a string of addressable RGB LEDs behind the TV to create the desired effect.

For all the hard work, [Andrew] was rewarded with an ambient lighting system that runs at a healthy 20fps and works with any HDMI video feed plugged into the TV. It even autoscales to work with video content shot in different aspect ratios so the ambient display always picks up the edge of the video content.

With 270 LEDs fitted, the result is an incredibly smooth and fluid ambient display we’d love to have at home. You can build one too, since [Andrew] shared all the code on Github. As an added bonus, he also gave the system an audio visualiser, and tested it out with some Streetlight Manifesto, the greatest third-wave ska band ever to roam the Earth. The Fourth Wave still eludes us, but we hold out hope.

We’ve seen plenty of hacks in this vein before; one of the most impressive hacked a smart TV into doing the video processing itself. Video after the break.

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Lamp Sheds Light On Air Quality

It can be difficult to appreciate when the air quality is decent and when it’s poor, unless conditions are so bad that you can literally see the smog hanging in the air. Rather than try to digest a bunch of air quality numbers, [guillaume_slizewicz] built Canari — a lovely lamp that sheds light on the air pollution problem by taking local air quality data and turning it into light patterns.

Canari is of course named after the brave birds that once alerted miners to dangerous air conditions before they were forced to switch to carbon monoxide sensors. This bird has a Raspberry Pi Zero W that gets air quality data from a public API and controls the lights with a PWM bonnet based on the concentration of particulates in the air. The more particulates, the dimmer the LEDs are, and the faster they fade in and out.

The main piece of data that Canari grabs is the amount of particulate matter, and the display can switch between representing the level of PM2.5 (particulate matter with diameter less than 2.5 micrometers)  in the air and PM10. Check out the demo and setup video after the break.

More of a numbers person? All you really need is a microcontroller, an air quality sensor, and a display.

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New Part Day: RP2040 Chips In Single Unit Quantities

Since the launch of the Raspberry Pi Pico back in January the little board with its newly-designed RP2040 microcontroller has really caught the imagination of makers everywhere, and we have seen an extremely impressive array of projects using it. So far the RP2040 has only been available on a ready-made PCB module, but we have news today direct from Eben Upton himself that with around 600k units already shipped, single-unit sales of the chip are commencing via the network of Raspberry Pi Approved Resellers.

This news will doubtless result in a fresh explosion of clever projects using the chip, but perhaps more intriguingly it will inevitably result in its appearance at the heart of a new crop of niche products that go beyond simple clones of the Pico in different form factors. The special ingredient of those two PIO programmable state machines to take the load of repetitive tasks away from the cores raises it above being merely yet another microcontroller chip, and we look forward to that feature being at their heart.

The Broadcom systems-on-chip that power Raspberry Pi’s existing range of Linux-capable boards have famously remained unavailable on their own, meaning that this move to being a chip vendor breaks further new ground for the Cambridge-based company. It’s best not to think of it in terms of their entering into competition with the giants of the microcontroller market though, because a relative minnow such as the RP2040 will be of little immediate concern to the likes of Microchip, ST, or TI. A better comparison when evaluating the RP2040’s chances in the market is probably Parallax with their Propeller chip, in that here is a company with a very solid existing presence in the education and maker markets seeking to capitalise on that experience by providing a microcontroller with that niche in mind. We look forward to seeing where this will take them, and we’d hope to eventually see a family of RP2040-like chips with different package and on-board peripheral options.

Neural Networks Emulate Any Guitar Pedal For $120

It’s a well-established fact that a guitarist’s acumen can be accurately gauged by the size of their pedal board- the more stompboxes, the better the player. Why have one box that can do everything when you can have many that do just a few things?

Jokes aside, the idea of replacing an entire pedal collection with a single box is nothing new. Your standard, old-school stompbox is an analog affair, using a combination of filters and amplifiers to achieve a certain sound. Some modern multi-effects processors use software models of older pedals to replicate their sound. These digital pedals have been around since the 90s, but none have been quite like the NeuralPi project. Just released by [GuitarML], the NeuralPi takes about $120 of hardware (including — you guessed it — a Raspberry Pi) and transforms it into the perfect pedal.

The key here, of course, is neural networks. The LSTM at the core of NeuralPi can be trained on any pedal you’ve got laying around to accurately reproduce its sound, and it can even do so with incredibly low latency thanks to Elk Audio OS (which even powers Matt Bellamy’s synth guitar, as used in Muse‘s Simulation Theory World Tour). The result of a trained model is a VST3 plugin, a popular format for describing audio effects.

This isn’t the first time we’ve seen some seriously cool stuff from [GuitarML], and it also hearkens back a bit to some sweet pedal simulation in LTSpice we saw last year. We can’t wait to see this project continue to develop — over time, it would be awesome to see a slick UI, or maybe somebody will design a cool enclosure with some knobs and an honest-to-god pedal for user input!

Thanks to [Mish] for the tip!

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Raspberry Pi RP2040: Hands-On Experiences From An STM32 Perspective

The release of the Raspberry Pi Foundation’s Raspberry Pi Pico board with RP2040 microcontroller has made big waves these past months in the maker community. Many have demonstrated how especially the two Programmable I/O (PIO) state machine peripherals can be used to create DVI video generators and other digital peripherals.

Alongside this excitement, it raises the question of whether any of this will cause any major upheaval for those of us using STM32, SAM and other Cortex-M based MCUs. Would the RP2040 perhaps be a valid option for some of our projects? With the RP2040 being a dual Cortex-M0+ processor MCU, it seems only fair to put it toe to toe with the offerings from one of the current heavyweights in the 32-bit ARM MCU space: ST Microelectronics.

Did the Raspberry Pi Foundation pipsqueak manage to show ST’s engineers how it’s done, or should the former revisit some of their assumptions? And just how hard is it going to be to port low-level code from STM32 to RP2040? Continue reading “Raspberry Pi RP2040: Hands-On Experiences From An STM32 Perspective”