Inputs Of Interest: The Svalboard Could Be Your Salvation

You know, sometimes dreams really do come true. When I told you about the DataHand keyboard almost four years ago, I never imagined I’d ever get to lay my hands on anything even remotely like it, between the original price point and the fact that they really, really hold their value. But thanks to [Morgan Venable], creator of the Svalboard, I can finally tell you what it’s like to type with your digits directionalized.

If you don’t recall, the DataHand was touted to be a total revolution in typing for RSI sufferers. It debuted in 1993 for a hefty price tag of about $1,500 — pretty far out of reach of the average consumer, but well within the budgets of the IT departments of companies who really wanted to keep their workers working. You want minimum finger travel? It doesn’t get more minimal than this concept of a d-pad plus the regular down action for each finger.

The Svalboard aims to be the new and improved solution for something that barely exists anymore, but still has a devoted following. Although the DataHand was built on a gantry and adjustable using knobs, the smallest fit possible on the thing is still rather big. Conversely, the Svalboard is fully customizable to suit any size hand and fingertip.

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Simon Says With An RP2040

The team of [Michael] and [Chimdi] from Cornell’s Designing with Microcontrollers (ECE 4760) Fall 2023 session designed a version of Simon Says on an RP2040 which they call Pico Says. It uses UDP packets over WiFi to communicate between the players, and supports VGA graphics for output. Each player’s hardware consists of a Pico W module plus a control panel containing the four LEDs and buttons ( red, green, yellow, and blue ) plus send and reset buttons.

For purposes of this lab, the modules were build on a solderless breadboard and used perfboard for the control panels. They weren’t entirely happy with their choice of UDP because they experienced frequent datagram dropouts in the noisy environment of the microcontroller lab. They also planned to implement sound effects, but ran out of time after spending too much time on the WiFi implementation, and had to drop that feature. In the end, however, they wrapped up their project and demonstrated a working game. We can only speculate whether this bonus lesson in resource management was intended by [Dr. Hunter Adams] or not.

Two ECE 4760 course references are highlighted in the write-up that helped them jump-start the project: the UDP and VGA examples for the Pico. These are good links to put in your RP2020 toolbox for future projects, in addition to the ECE 4760 course home page itself. We’ve covered several of these projects recently, as well as the curriculum switch from the Microchip PIC32MX-based Microstick II to the RP2040 last Spring.

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Building A Loop Station With An RP2040

Loop stations are neat things, able to replay one or more loops of audio over and over again while you perform over the top of them. Musicians like [Marc Rebillet], [Reinhardt Buhr], and [Dub FX] have made careers out of this style of performance. [Yaqi Gao], [Xiaoyu Liang] and [Alina Wang] decided to build a loop station of their own, using the popular RP2040 chip.

At its simplest, a loop station must take in audio, record it, and then play it back. Generally, it can do this with several tracks and mix them together, while also mixing in the incoming audio as well. The group achieved this by inputting a guitar signal to the chip via an amplifier and the onboard analog-to-digital converter. The audio can be recorded as desired, and then played back via an external digital-to-analog converter. Live audio from the guitar is also passed through to allow performing over the recorded sound. The group also used an external half-megabyte FRAM chip to allow storing additional audio sample data, which can be trucked out over serial and saved.

It’s not the cleanest loop station in the world, with a relatively low sample rate causing some artifacts. Regardless, it definitely works, and taught the group plenty about working with digital audio in the process. For that reason alone, we’d call it a success.

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The ScottoKatana Keyboard Is Cutting-Edge

The lovely thing about a hobby like keyboard building is that the melting pot of designs manages to never turn into a nasty porridge. Rather, it remains a tasty chili that keeps getting more flavorful with time. It’s a simple recipe, really; someone becomes dissatisfied enough with their peripherals to do something about it, often trying various designs until they either settle on one, or come up with yet another awesome variant that suits their needs — and possibly someone else’s down the line.

The inimitable [Joe Scotto] has happened upon the katana layout, which has an inverse left-hand row stagger that lends symmetry to the design, and Scotto-ized it into a 33-key build that he says is the best-sounding one yet with lubed Gateron Milky Yellows.

The case and the keycaps are both 3D-printed, and as with all Scotto builds, it is beautifully hand-wired. This one uses an RP2040 Pro Micro, but an ATMega Pro Micro will work, too.

Everything is available on GitHub, and [Joe] promises a typing test soon, as well as a gasket version that foregoes the integrated plate.

Do you need a fast keyboard? Like, ridiculously fast? Then you should use an FPGA.

Via KBD and Make:

The Pi Pico replacement board in question, assembled, held diagonally in some type of holder

ProPico For Your Pro Pico Needs

Ever feel like the Pi Pico board could be doing way more given its footprint? Does it bother you that the RP2040’s ADC quality is even further decreased because of the noisy onboard switching regulator? Miffed about decisions like the MicroUSB socket, the 2MB flash, or lack of the reset button? [Dmytro] brings us an open-source Pi Pico design, sporting the same RP2040 and a fully compatible footprint, but adding a number of improvements to its surroundings.

There’s a good few additions, all of them hacker-friendly – [Dmytro] adds comfortably-spaced reset and boot buttons, a USB-C socket, a dedicated low-noise voltage reference for the ADC, one more LED, and an I2C EEPROM footprint socket that is compatible with FRAM chips. Everything worth preserving is preserved – the pinout stays the same, including the SWD connector, which now sports an extra RESET pin. The bottom side USB testpoints remain, with only the four testpoints changed for more useful signals. Last but not least, the switching regulator is replaced by the venerable 1117 – you lose the ability to power your Pico from two AAs, and the capacitor series resistor requirement isn’t great, but you can easily put one of the drop-in 1117 replacement regulators on there.

What’s great is that the design is fully open-source, with KiCad files available. Want to design your own Pi Pico footprint board, improve upon this one even further, or maybe make a more tailored one? Treat yourself to the GitHub repository! There’s also a pinout diagram and a KiCanvas schematic for all your tinkering needs. We’ve covered drop-in replacements for classic drawer-inhabiting parts like the Pi Zero, for the 7805 (twice!), the 6502 CPU, and even for the DE9 serial port connector. No matter the purpose, they’re always a joy to see.

A microwave imaging setup. On the left is a monitor displaying a monochrome GUI. In the center is the RP2040-based positioning and measurement system, and on the right is a vector network analyzer.

Precise Positioning With The RP2040

Microwave imaging is similar to CT imaging, but instead of X-rays, the microwaves are used to probe the structure and composition of an object. To facilitate experimentation with microwave imaging, [Zehao Li] and [Kapil Gangwar] developed a system based on the RP2040 to control the height and rotation of a test object.

Their control system has a refreshingly physical user interface—a keypad. The keypad is used to configure the object’s position and the scanning step size, while user menus and the sample position are displayed in a clean and uncluttered interface over VGA. The RP2040 runs a multi-threaded program to handle user input, VGA display, and precise driving of two stepper motors for sample positioning.

The microwave imaging was performed by measuring the RF transmission over 2.5-8 GHz between two Vivaldi antennas on either side of the sample at a variety of angles. 2D cross-sections of the test object were reconstructed in Matlab using filtered back-projection. In this proof-of-concept demonstration, a commercial vector network analyzer was used to collect the data, but one could imagine migrating to a software defined radio (SDR) in the future.

A video demonstrating the system is embedded below the break. If you’re interested in DIY radio imaging, you might be interested in this guide to building your own synthetic aperture radar setup, or this analysis of an automotive radar chip.

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Sound-Reactive Light Saber Flips Allegiance Via Vowel Sounds

Students [Berk Gokmen] and [Justin Green] developed an RP2040-based LED-illuminated lightsaber as a final project with a bit of a twist. It has two unusual sound-reactive modes: disco mode, and vowel detection mode.

Switching allegiances (or saber color, at least) is only a sound away.

Disco mode alters the color of the saber dynamically in response to incoming sounds. Color and brightness are altered in response to incoming frequencies picked up by the on-board microphone, making a dynamic light show that responds particularly well to music.

The second mode is vowel detection, and changes the lightsaber’s color depending on spoken sounds. The “ee” sound makes the saber red, and the “ah” sound turns it blue. This method requires a lot of processing and filtering, and in the end it works, but is quite dependent on individual speakers for calibration.

The sound functionality centers around FFTs (Fast Fourier Transforms) which are fundamental to processing signals like audio in a meaningful way, and is a method accessible to embedded devices like microcontrollers with ADCs.

The lightsaber is battery-powered and wireless, and there are loads of details about the finer points of the design (including challenges and tradeoffs) on the project page, and the source code is available on GitHub. A video demonstration and walkthrough is embedded below.

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