Building A Loop Station With An RP2040

January 11, 2024 by 9 Comments

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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NASA Adjusts Course On Journey To The Moon

January 11, 2024 by 61 Comments

It’s already been more than fifty years since a human last stepped foot on another celestial body, and now that NASA has officially pushed back key elements of their Artemis program, we’re going to be waiting a bit longer before it happens again. What’s a few years compared to half a century?

The January 9th press conference was billed as a way for NASA Administrator Bill Nelson and other high-ranking officials within the space agency to give the public an update on Artemis. But those who’ve been following the program had already guessed it would end up being the official concession that NASA simply wasn’t ready to send astronauts out for a lunar flyby this year as initially planned. Pushing back this second phase of the Artemis program naturally means delaying the subsequent missions as well, though during the conference it was noted that the Artemis III mission was  already dealing with its own technical challenges.

More than just an acknowledgement of the Artemis delays, the press conference did include details on the specific issues that were holding up the program. In addition several team members were able to share information about the systems and components they’re responsible for, including insight into the hardware that’s already complete and what still needs more development time. Finally, the public was given an update on what NASA’s plans look like after landing on the Moon during the Artemis III mission, including their plans for constructing and utilizing the Lunar Gateway station.

With the understanding that even these latest plans are subject to potential changes or delays over the coming years, let’s take a look at the revised Artemis timeline.

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a) Schematic illustration of energy storage process of succulent plants by harnessing solar energy with a solar cell, and the solar cell converts the energy into electricity that can be store in APCSCs of succulent plants, and then utilized by multiple electrical appliances. b–d) The energy is stored in cactus under sunlight by solar cell and then power light strips of Christmas tree for decoration.

Succulents Into Supercapacitors

January 11, 2024 by 17 Comments

Researchers in Beijing have discovered a way to turn succulents into supercapacitors to help store energy. While previous research has found ways to store energy in plants, it often required implants or other modifications to the plant itself to function. These foreign components might be rejected by the plant or hamper its natural functions leading to its premature death.

This new method takes an aloe leaf, freeze dries it, heats it up, then uses the resulting components as an implant back into the aloe plant. Since it’s all aloe all the time, the plant stays happy (or at least alive) and becomes an electrolytic supercapacitor.

Using the natural electrolytes of the aloe juice, the supercapacitor can then be charged and discharged as needed. The researchers tested the concept by solar charging the capacitor and then using that to run LED lights.

This certainly proposes some interesting applications, although we think your HOA might not be a fan. We also wonder if there might be a way to use the photosynthetic process more directly to charge the plant? Maybe this could recharge a tiny robot that lands on the plants?

Faking Bluetooth LE With An NRF24L01+ Module

January 11, 2024 by 11 Comments

Despite the name, Bluetooth Low Energy (BLE) has very little to do with the original Bluetooth, other than its use of the same 2.4 GHz frequencies. This is where [Dmitry] got the idea to use a 2.4 GHz nRF24L01+ module to implement his very own BLE device, without the typical BLE chipset. This should be easy, since this popular IC supports GFSK modulation, 1 MHz channels and the 1 MBit data rate of BLE.

Despite of how simple BLE seems to implement, [Dmitry] quickly came across a range of issues due to limitations of the nRF24L01+. These include no support for a 24-bit CRC, a too sluggish PLL cycling for BLE’s frequency hopping, and as the coup de grâce, a lack for incoming data packets larger than 32 bytes — which destroyed any hope of accepting incoming connections.

Unperturbed, [Dmitry] set to work implementing what would work on this IC: broadcasting BLE packets. In the article he covers the entire code (in C) that allows the nRF24L01+ to send broadcast packets and any BLE-supporting device that’s listening to receive them. Admittedly not as useful as having a fully functional BLE stack, but good enough for broadcasting something like sensor data. It also raises the question of which alternative released in the intervening decade to the venerable nRF24L01+ might fill in the missing features, without making a dedicated BLE IC (or ESP32 variant) look more cost-effective.

It’s always a good day when a new project from [Dmitry] hits the tip line. We’ve previously covered his impressive efforts to add more RAM to the RP2040, and his business card that can boot Linux on an ATSAMD21.

19th Century Copy Machine: The Cyclostyle

January 10, 2024 by 15 Comments

In the 2020s photocopiers are getting a bit exotic, although they are not gone yet. But these days, you are more likely to simply print multiple copies of a document. However, it wasn’t long ago that making a copy of a document was a tall order. Carbon paper was fine if you were typing and only needed a few copies. But in the late 1800s to early 1900s, several solutions were available, including a beautiful early mimeograph known as the Cyclostyle at [Our Own Devices], examined in the video below.

The Cyclostyle was possibly inspired by a hectograph (something we looked at before). The Cyclostyle was originally a special stylus used to remove wax from a paper stencil. Then, a process similar to screen printing would make copies for you.

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The Hobbes OS/2 Archive Will Shut Down In April

January 10, 2024 by 27 Comments

The Hobbes OS/2 Archive is a large collection of OS/2 software that has been publicly available for many years, even as OS/2 itself has mostly faded into obscurity. Yet now it would appear that the entity behind the Hobbes OS/2 Archive, the Information & Communication Technologies department at the New Mexico State University, has decided to call it quits — with the site going permanently offline on April 15th, 2024.

Fortunately, from a cursory glance around the comment sections over at Hacker News and other places, it seems that backup efforts have already been made, and the preservation of the archive’s contents should be secure at this point in time. Regardless, it is always a shame to lose such a central repository, especially since IBM’s OS/2 operating system is still anything but dead. Whether for hobbyist, industrial or commercial use, there is still a vibrant community around today, as we noted in 2019 already in relation to the NYC’s subway system.

Beyond downloaded copies and boxed CDs bought on EBay, you can even get a modernized version of OS/2 called ArcaOS, which even comes with commercial support. Whatever the fate is of the Hobbes OS/2 Archive’s data, we hope it finds a loving new home somewhere.

Pico-Sized Ham Radio

January 10, 2024 by 18 Comments

There are plenty of hobbies around with huge price tags, and ham radio can certainly be one of them. Experienced hams might have radios that cost thousands of dollars, with huge, steerable antennas on masts that can be similarly priced. But there’s also a side to the hobby that throws all of this out of the window in favor of the simplest, lowest-cost radios and antennas that still can get the job done. Software-defined radio (SDR) turned this practice up to 11 as well, and this radio module uses almost nothing more than a microcontroller to get on the air.

The design uses the capabilities of the Raspberry Pi Pico to handle almost all of the radio’s capabilities. The RF oscillator is driven by one of the Pico’s programmable I/O (PIO) pins, which takes some load off of the processor. For AM and SSB, where amplitude needs to be controlled as well, a PWM signal is generated on another PIO which is then mixed with the RF oscillator using an analog multiplexer. The design also includes a microphone with a preamplifier which can be fed into a third PIO; alternatively it can receive audio from a computer via the USB interface. More processor resources are needed when generating phase-modulated signals like RF, but the Pico is still quite capable of doing all of these tasks without jitter larger than a clock cycle.

Of course this only outputs a signal with a few milliwatts of power, so for making any useful radio contacts with this circuit an amplifier is almost certainly needed. With the heavy lifting done by the Pico, though, the amplifier doesn’t need to be complicated or expensive. While the design is simple and low-cost, it’s not the simplest radio possible. This transmitter sends out radio waves using only a single transistor but you will be limited to Morse code only.

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